Best weld. Varieties and methods of performing welding seams. Types of welds and joints

A weld seam is one of the most reliable ways to join parts. It is used in industry and in general Everyday life... Every home craftsman uses welding from time to time. It is good if he knows how to cook himself, but often he has to turn to specialists. But welding is quite possible to learn. You should start with the simplest: electric welding for beginners is, first of all, learning how to perform various seams. More complex work can be performed only by gaining experience. Let's take a look at the basics of technology and some of the tricks of the welding process, as well as the equipment and materials used.

Types of welding machines

For the right choice welding machine, it is necessary to take into account all the pros and cons of various types and models of welders.

Transformers- the simplest and most traditional devices, rather heavy in weight, made on the basis of a step-down transformer, which brings the voltage value up to that required for operation. The peculiarity of transformers is to operate on alternating current, which creates an unstable arc. In combination with an increased amount of slag and gas impurities, such an arc promotes metal spatter and spoils the appearance of the weld. A high-quality seam with such a device can be made by an experienced welder with the skills of working on a transformer.

Simple AC Apparatus

Rectifiers- welders who can convert alternating current into direct current and lower the mains voltage using semiconductor diodes. Constant current gives a stable arc and allows you to make the weld uniform and tight, strong and beautiful. The rectifier is universal, all types of electrodes are suitable for it, all types of metals can be cooked with such an apparatus: stainless steel, aluminum, copper, titanium, various alloys.

Universal welding machine suitable for all types of electrodes

Inverters- very popular because of their low weight, excellent functionality, automated settings. Such specifications allow beginners to work on it. The design of the device includes a number of blocks that convert the alternating current of the network into direct current of high power. The advantage of this type of welder is:

the possibility of precise settings;
performing a wide range of tasks;
stable arc;
resistance to voltage surges;
high quality welding, smooth seam;
work with all types of electrodes;
connection of all types of metals of any thickness and position in space.
has additional functions to prevent sticking of the electrode and tear-off drops;
the possibility of igniting the electrode at the maximum supply of current;

Of the minuses, it can be noted:

the need for frequent cleaning from dust;
limited cable length equal to 2.5 m;
the inability to work at an air temperature below - 15 degrees.

The inverter is suitable for the novice welder

Semiautomatic devices - are of two types. The former increase the productivity of welding work due to continuous wire feeding. In this case, you do not need to constantly change the electrodes. The seam is smooth, continuous and free of defects. The latter work in a gas environment, for this they use oxygen, nitrogen and carbon dioxide, as well as argon and helium. Gas welding has the following advantages:

one apparatus designed to work with both gas and wire;
excellent quality and aesthetics of the seam;
stable, even arc;
high functionality;
the ability to weld complex joints.

With this machine, you can make a high-quality weld seam.

What a novice welder will need to work

First of all, you need to prepare equipment and clothing.

Tools and means of protection

You will definitely need a welding machine, a set of electrodes, a hammer and a chisel for knocking down the slag, a metal brush for cleaning the seams. The electric holder serves for clamping, holding the electrode and supplying current to it. A set of templates is also needed to check the seam dimensions. The diameter of the electrode is selected depending on the thickness of the metal sheet. Don't forget about protection. We are preparing a welding mask with a special light filter that does not transmit infrared rays and protects the eyes. The same function is performed by screens and shields. A canvas suit, consisting of a jacket with long sleeves and smooth trousers without cuffs, leather or felted shoes for protection against metal splashes and gloves or mittens, canvas or suede with slouching sleeves. This tight, closed clothing protects the welder from the ingress of molten metal onto the body.

There are special protective equipment that are used for working at height and inside metal objects, when working in a prone position. In such cases, you will need dielectric boots, a helmet, gloves, a mat, knee pads, armrests, and for high-altitude welding you need a safety belt with straps.

Which electrodes to choose

There are various types and brands of electrodes. This is due to the need to select the metal of the parts to be joined and the same metal of the electrode.

Each electrode has a marking that gives the welder all the information he needs. Learning to read the markings is easy.

The electrodes have a special marking

Often on top they are covered with various coatings, which give the electrodes the properties necessary for welding different metals and working conditions. Here is a table of the classification of electrodes by type of coating and application.

Special coating gives the electrodes the special properties required for welding different metals

The classification of electrodes by type and purpose is reflected in the product labeling.

Electrodes differ in type and purpose

Types of welds

Joint welds are subdivided according to location, strength, technology, design features. Types of seam locations:

Lower. The simplest and most convenient, thanks to the force of gravity, the metal fills the gap between the parts. This is the strongest and most economical seam.
Horizontal. The workpieces are located perpendicular to the electrode and the seam goes horizontally. Part of the metal leaves the welding area and the electrode is consumed faster.
Vertical. In this case, the workpieces are also located perpendicular to the electrode, but the formation of the seam proceeds vertically. The molten metal tends downward, the consumption of the electrode is significant.
Inclined. The movement of the welder's arm is inclined. It is used for corner and tee connections.
The ceiling seam is located above the master.

Structural division:

Butt. The butt joint is quite durable and economical, it does not distort the joint surface. This is a universal connection.
Overlapping parts are welded when there is not enough space for a butt seam. The thickness of the workpieces should not be more than 8-10 mm.
It is recommended to weld the fillet weld on both sides, while the workpieces are located at an angle to each other. This seam is not easy to perform due to the increase in the heat-affected zone and the high consumption of the electrode.
A tee is a fillet weld where the planes of parts are welded perpendicularly. The seam is formed on both sides, it is rather complicated.
A seam for electric rivets is used when there is no need for a sealed seam, it is the most economical and invisible.

Welding can be carried out both in one layer and in several layers for thick workpieces.

How to Learn to Cook by Welding - A Beginner's Guide

Welding is a high temperature process. For its implementation, an electric arc is formed and held from the electrode to the workpiece to be welded. Under its influence, the base material and the metal rod of the electrode are melted. As experts say, a weld pool is formed, the base and electrode metal is mixed in it. The size of the resulting pool directly depends on the selected welding mode, spatial position, arc speed, shape and size of the edge, etc. On average, its width is 8-15 mm, length 10-30 mm and depth - about 6 mm.

The coating of the electrode, the so-called coating, when melted, forms a special gas zone in the arc region and above the bath. It displaces all air from the weld area and prevents the molten metal from interacting with oxygen. In addition, it contains vapors of both the base and electrode metals. Slag forms on top of the seam, which also prevents the melt from interacting with air, which negatively affects the quality of welding. After gradual removal of the electric arc, the metal begins to crystallize and a seam is formed that unites the parts to be welded. On top of it there is a protective slag layer, which is subsequently removed.

In the process of making a weld, the coating of the electrode melts, forming a special gas zone. Inside it, there is a mixing of the base metal and the electrode.

For beginner welders, it is best to get the first experience under the guidance of a specialist who can fix possible mistakes and give useful advice. You should get to work, securely fixing the part. In order to fire safety you need to put a bucket of water near you. For the same reason, you must not carry out welding work on a wooden base and carelessly treat even very small residues of the used electrode.

Welding machine connection

For welding to work safely, you need to connect the machine to the network, observing the following rules:

First you need to check the voltage and frequency of the current. This data must be the same on the network and on the body of the device.
We set the calculated value of the current power on the welding machine, which must correspond to the selected diameter of the electrode. If the welder's settings block allows you to select the voltage, you need to set it right away. Connection is made through a special plug and a grounding lug.
We securely fasten the "grounding" clamp. We check that the cable is insulated and carefully tucked into a special holder.
Be sure to check all connections, cables, plugs.
You can use a special extension cord that connects without intermediate connections.
In older houses with poor wiring, voltage drops may occur. It stops the work process and can damage the welding equipment. In this case, you need an electric generator that will provide the voltage at the operating level.

The welding machine is simple

How to choose the right current

Welding current is an important indicator of welding and determines the type and nature of the seam and work performance. The higher the current, the more stable the arc and the greater the penetration depth. The strength of the current depends on the location of the workpieces in space and on the size of the electrode. The highest value is set for welding horizontal workpieces. For vertical seams, the amperage value is applied less by 15%, and with ceiling seams - by 20%.

The current strength depends on the position of the workpieces and on the size of the electrode

How to light the arc

The first way is touch. To do this, set the electrode at an angle of about 60 ° relative to the product. We slowly draw it over the surface. Sparks should appear, now we touch the electrode to the metal and raise it to a height of no more than 5 mm.

If the operation was performed correctly, an arc will ignite. The 5 mm gap must be maintained throughout the entire weld. It should be borne in mind that with proper welding of the metal by electric welding, the electrode will gradually burn out, therefore we constantly bring it slightly closer to the metal. Move the electrode slowly, if it suddenly sticks, you will have to slightly swing it to the side. If the arc does not strike, it may be necessary to increase the amperage.

The second way is striking. You need to bring the electrode to the surface of the workpiece and strike it over the part, as if lighting a match. It is possible to facilitate the ignition of the electrode by tapping the coating from its edge.

Electrode tilt and movement

After you can easily ignite and maintain the arc, it's time to move on to fusing the bead. We light the arc, slowly and smoothly move the electrode horizontally, performing light oscillatory movements with it. At the same time, the molten metal is "scooped up" to the very center of the arc. This should result in a strong weld with small weld waves.

The angle of inclination of the electrode for a novice welder is better to observe about 70 degrees, that is, with a slight deviation from the vertical. Below is a diagram of arc welding.

The angle of inclination of the electrode is about 70 degrees

If in the process of welding parts the electrode burns out almost completely, and the seam is not yet completed, the work is temporarily stopped. We change the used element to a new one, remove the slag and continue working. At a distance of about 12 mm from the depression formed at the end of the seam, which is also called a crater, we ignite an arc. We bring the electrode to the recess so that an alloy is formed from the metal of the old and newly installed electrode, after which the seam welding continues.

In the process of welding, the electrode makes certain movements, mainly translational, longitudinal and transverse. Their combinations are made up different kinds seams, the most common are shown in the diagram

The trajectory of the arc during the welding of parts can be made in three directions:

Translational. Assumes the movement of the arc along the axis of the electrode. Thus, it is easy enough to maintain a stable arc length.
Longitudinal. Forms a filament welding roller, the height of which depends on the speed at which the electrode moves and its thickness. This is a normal seam, but very thin. To fix it, in the process of movement of the electrode along the welded seam, transverse movements are also performed.
Transverse. Allows to obtain the desired seam width. Performed by swinging movements. Their width is selected based on the size and position of the seam, the shape of its cutting, etc.

In practice, all three basic movements are used, which are superimposed on one another and form a certain trajectory. There are classic options, but each master usually has his own handwriting. The main thing is that in the course of work the edges of the elements to be joined are well melted, and a seam of a given shape is obtained.

As a rule, all three directions apply, they can overlap and form a trajectory

Welding seams

Ceiling weld

This seam is considered the most difficult, since the weld pool is turned upside down and is located above the welder. The electrode is chosen no more than 4 mm and taken aside a little so that the metal does not spread. Use a short arc and completely dry electrodes and a thin overhead weld. The movement takes place towards oneself, so it is easier for the welder to control the quality of the seam. There are several ways to do it:

ladder;
crescent;
backward.

The ceiling seam is considered the most difficult

Video: performing a ceiling seam

Vertical

When performing such a seam, you can lead the electrode from top to bottom or bottom to top. To prevent the metal from flowing down, the electrode should be positioned at an angle of 45-50 degrees downward from the perpendicular position. Experienced welders recommend making this seam in one pass.

When making a vertical seam, the electrode is positioned at an angle of 45-50 degrees

Video: vertical seam

23.03

Making a horizontal seam

When performing such a seam, the main difficulty lies in the flow of metal down. To solve this problem, the welder must adjust the angle of inclination of the electrode and the travel speed. Welding is carried out from left to right or from right to left.

When performing a horizontal seam, you need to correctly select the angle of inclination of the electrode and the speed of passage

Angular

When forming fillet or tee seams, the parts are positioned at different angles with a boat so that the molten metal flows into the corner. Then they are tacked by welding on both sides, one edge of the structure should be slightly higher than the other. The movement of the electrode starts from the lowest point.

In fillet welding, the movement of the electrode starts from the lowest point

Features of pipeline welding

Electric arc welding can make a vertical seam, which is located on the side of the pipe, horizontal - along its circumference. As well as the ceiling and bottom, located, respectively, above and below. Moreover, the latter is considered the most convenient to perform. Steel pipes are usually butt-welded with the obligatory penetration of all edges along the wall height. To reduce sagging inside the pipe, an electrode inclination angle of no more than 45 ° relative to the horizontal is selected. Joint height - 2-3 mm, width - 6-8 mm. When welding with an overlap, the height of the seam is about 3 mm, and the width is 6-8 mm.

Before starting to weld the pipe with electric welding, we carry out preparatory work:

thoroughly clean the part;
if the ends of the pipe are deformed, cut or straighten them;
we clean the edges. We clean at least 10 mm of the outer and inner planes adjacent to the edges of the pipe to a metallic sheen.

Now you can start welding. All joints are processed continuously, up to complete welding. Swivel and non-swivel joints of pipes with a wall width of up to 6 mm are made in at least 2 layers. With a wall width of 6-12 mm, three layers are performed, more than 19 mm - four. The peculiarity of pipe welding is that each seam that is applied to the joint must be cleaned of slag, after which the next one is performed. The first seam is the most critical. It should completely melt all edges and blunts. It is especially carefully examined for cracks. If they are present, they are melted or cut and the fragment is welded again.

The final layer is made as even as possible with a smooth transition to the base metal

The second and all subsequent layers are performed by slowly turning the pipe. The end and beginning of all layers must be shifted relative to the previous layer by 15-30 mm. The final layer is made with a smooth transition to the base metal and with an even surface. To improve the quality of welding pipes by electric welding, each subsequent layer is carried out in the opposite direction relative to the previous one, and their closing points are necessarily spaced apart.

Self-welding is a rather complicated undertaking. However, if you wish, you can still master it. You need to learn the basic rules of the process and gradually learn how to perform the simplest exercises. You do not need to spare time and effort to master the basics, which will become the basis of mastery. Subsequently, you can safely move on to more complex techniques, honing your skills.

You can easily learn how to apply the correct and high-quality weld seam on your own. Electric or arc welding, designed for novice craftsmen, implies initial training in the formation of these permanent-type connections. You should start with the simplest, gradually moving on to more complex connections, when you can accumulate a sufficient amount of experience.

For the implementation of welded joints, the preparation of the appropriate equipment is mandatory. To work with electric arc welding, you need to take the following tools and materials.

Directly the welded equipment itself, which is of different types.
Electrodes of the required diameter - it usually depends on the thickness of the elements to be connected.
A special sharpened hammer that will knock down the slag.
Metal brush for cleaning the area of the metal where the weld is formed.

When forming a joint, remember the appropriate safety measures. It is not possible to carry out work without a suitable mask equipped with special light filters.

It is advisable to wear rather tight clothes with long sleeves, gloves made of suede materials. In addition, you should take a rectifier, or a transformer if the equipment is quite old. Recently, however, more and more welds are applied using inverter equipment, which is equipped with everything necessary to convert AC to DC.

Work technology

In order to correctly place the molten electrode on the formed weld, it should be borne in mind that welding is not a very simple and safe technology. First of all, this implies the use of high temperature, which must exceed the melting point of steel.

Under its direct influence, the base metal and the electrode are melted. Accordingly, a so-called weld pool is formed, where the metals of the workpiece and the electrode are mixed, as a result of which a welded joint or seam is formed.

The size of the weld pool directly depends on what settings were made on the equipment, the location in space, the speed with which the electrode moves, the gap between the welded elements. Formation of the correct weld seam implies an average joint width of 4 to 30 mm, depending on the thickness of the workpieces.

Electric arc technology involves the use of electrodes with so-called coating. When voltage is applied to the electrode and welded elements, it forms a special gas zone above the bath. Due to it, there is an absolute displacement of air, which does not allow direct contact between oxygen and the metals being welded. When the elements are welded, slag forms on the surface of the joint, which also prevents the molten iron from contacting with air.

The formation of the correct weld is carried out when the electric arc is removed: the metal begins to gradually cool down and form a crystal lattice. The protective slag layer should be removed after the metal has hardened.

Electric arc welding basics

In order to make a reliable welded joint and correctly place the molten electrode material, it is necessary to pay close attention to the beginning of the work. It's best to start mastering this work under the supervision of an experienced welder, who will avoid the most typical mistakes and advise if necessary.

The parts to be connected together must be rigidly fixed. Due to the fact that work is carried out at high temperatures, it is necessary to provide for all measures related to fire safety. You must install a bucket of water near you. Do not work on wood substrates.

The earthing clamp is fixed to the elements to be welded. Before that, you should carefully check the quality of its insulation. If it is damaged, do not use this cable. In addition, it must be securely fastened in a special clip.

Competently selected equipment settings allow you to apply the electrode smoothly and evenly, due to which the metal is welded onto the elements to be welded.

When all this preparatory work is completed, carefully ignite the arc. This should be done as follows: the electrode is held at an angle to the workpieces of about 60 degrees, it is slowly led along the metal surface until sparks appear. Then they lightly touch the workpieces and move them away from them at a distance of about 5 mm, thereby forming an electric arc.

Such a gap will have to be maintained throughout the entire operating time. If everything was done correctly, the electrode will gradually melt and burn out, so it will have to be slowly brought to the workpieces, thereby maintaining the required distance. It should not be brought closer, as it can stick. If the arc does not occur, you will have to increase the amperage on the equipment.

Weld seam: how to move the electrode?

During welding, the electrode should be moved along one of three paths.

Translational - the electric arc is directed along the axis of the connected elements. This allows not only to maintain its constant combustion, but also to form a rather thin and strong weld.
Longitudinal - allows you to provide a thread seam of various heights, which will directly depend on the speed at which the electrode moves. In fact, the connection turns out to be very strong, but to strengthen it, you will have to make some lateral movements.
Transverse - ensures the formation of the required width of the welded joint. It involves performing oscillatory movements. The seam width is selected based on the thickness of the elements to be joined, their dimensions and a number of other parameters.

Usually, when carrying out work, all these movements are used, which, when combined with each other, form a specific trajectory. It is usually different for each welder. In principle, the trajectory itself is not too important, the main thing is that the edges of the workpieces are melted as best as possible and, accordingly, a seam with predetermined parameters is obtained.

Welding of pipelines: technology features

It should be noted that welding implies the formation of not only horizontal, but also vertical seams, which allows welding, including industrial pipelines, which need to be made of the highest quality connection. In this regard, such work is allowed only to experienced welders who have all Required documents, testifying to their high qualifications.

Unlike flat parts, when welding pipes, the electrode is held at an angle of 45 degrees. The maximum height of this joint should be no more than 4 m.Depending on the thickness of the pipes, the width of the seam can be quite large - in some cases up to 4 cm.When carrying out industrial work, in order to obtain a full-fledged and durable connection, the areas where the seam will form are cleaned of fat , rust and other contaminants that can reduce the strength of the seam.

Welding implies constant improvement of skills, only in this case it will be possible to obtain the highest quality connection that will serve for a long time.

The ultimate goal of any welder is to obtain a quality weld. The strength and durability of the connection of parts depends on this. Correct connection is essential for successful operation; choose the current strength, the angle of inclination of the electrode; good command of the seam technique. The result correct work there will be reliable welding of metal parts.

Welding seams are classified according to several criteria. The types and types of welded joints should be considered sequentially, delving into the intricacies of the process. The seam is influenced by the location, direction and trajectory of the electrode.

After fixing the selected electrode in the clamp, setting the current, connecting the polarity, the welding process begins.

Each technician has a preferred electrode angle. Many consider 70 ° from a horizontal surface to be optimal.

In this case, an angle of 20 ° is formed from the vertical axis. Some work at a maximum angle of 60 °. In general, most training guidelines have a range of values from 30 ° to 60 ° from the vertical axis.

In certain situations, when welding in hard-to-reach places, it is necessary to orient the electrode strictly perpendicular to the surface of the material to be welded.

You can also move the electrode in different ways, in opposite directions: from yourself or towards yourself.

If the material requires deep heating, then the electrode is led to itself. Following him in the direction of the welder, the working area stretches. The resulting slag covers the place of the alloy.

If the work does not imply strong heating, then the electrode is moved away from itself. The welding zone "crawls" behind it. The heating depth with this type of seam is minimal. With direction, the question is clear.

Trajectory of movement

The trajectory of the electrode movement has a particular effect on the seam. In any case, it has an oscillatory character. Otherwise, the two surfaces cannot be stitched together.

Oscillations can look like zigzags with different steps between sharp corners of the trajectory. They can be smooth, reminiscent of movement along an offset figure eight. The trajectory can be like a herringbone or an uppercase Z with monograms at the top and bottom.

The perfect seam has a constant height, width, uniform appearance without defects in the form of craters, undercuts, pores, lack of penetration. The name of the possible flaws speaks for itself. Having worked well the skills, you can successfully apply any seam, weld a variety of metal parts.

Standards and the concept of leg

The weld seam begins to form in the working area in the molten state of the metals, and is finally formed after solidification.

The existing classification groups seams according to various criteria: the type of connection of parts, the resulting shape of the seam, its length, the number of layers, orientation in space.

The types of possible welded joints are shown in the standard for manual and arc welding GOST 5264. The joints performed by arc welding in an atmosphere of shielding gas are standardized by the document GOST 14771.

In GOST there is a designation for each welded joint, as well as a table containing the main characteristics, in particular the values of the leg of the weld.

What is a leg, it is quite simple to understand by looking at the drawing of the parts to be connected. This is the side of a notional isosceles triangle of maximum dimensions that will fit in cross section seam. A correctly calculated leg value guarantees a firm connection.

For parts of uneven thickness, the cross-sectional area of the part in its thinnest part is taken as a basis. You should not try to increase the leg unnecessarily. This can lead to deformation of the welded structure. In addition, the consumption of materials will increase.

Checking the dimensions of the leg is carried out using universal reference templates presented in the special literature.

Connection types

Depending on the relative position of the parts, welding joints occur:

end-to-end;
overlap;
angular way;
in a T-shaped way.

In butt welding, the ends of two parts located in the same plane are welded. The joint can be made with flanging, without bevel and with bevel. The bevel shape may resemble the letters X, K, V.

In some cases, welding is done with an overlap, then one part is partially hoisted on top of another, located in parallel. The combined part is an overlap. In this case, welding is done without bevel on both sides.

It is often necessary to make a welded corner. Such a connection is referred to as an angular type. It is always performed on both sides, it may not be chamfered or be chamfered on one edge.

If the welded parts result in the letter T, then a T-joint has been made. Sometimes T-welded parts form an acute angle.

In any case, one part is welded to the side of the other. Welding is carried out on both sides without bevel or with bevels on each side.

Form and length

The shape of the seam can be convex, even (flat). Sometimes it becomes necessary to make a concave shape. Convex joints are designed for heavy loading.

The concave places of the alloys withstand dynamic loads well. Flat seams, which are most often made, are characterized by versatility.

In length, the seams are continuous, having no intervals between the fused joints. Sometimes intermittent stitches are sufficient.

An interesting industrial variety of an intermittent seam is a connection that forms a resistance seam welding. It is done on special equipment equipped with rotating disc electrodes.

They are often called rollers, and this type of welding is roller. Solid connections can also be made on such equipment. The resulting seam is very strong, absolutely tight. The method is used on an industrial scale for the manufacture of pipes, containers, sealed modules.

Layers and arrangement in space

The metal seam can consist of a bead made in one pass. In this case, it is called single layer. With a large thickness of the parts to be welded, several passes are performed, as a result of which beads are successively formed one on top of the other. Such a welding joint is called a multilayer one.

Given the variety of production situations in which welding takes place, it is clear that the seams are oriented differently in each specific case. There are lower, upper (ceiling), vertical and horizontal seams.

Vertical seams are usually welded from bottom to top. The trajectory of movement of the electrode along the crescent, herringbone or zigzag is used. It is more convenient for novice welders to move with a crescent moon.

In horizontal welding, several passes are made from the lower edge of the parts to be joined to the upper edge.

In the lower position, butt welding is carried out or in any angular way. A good result is obtained by welding at an angle of 45 °, "boat", which can be symmetrical and asymmetrical. When welding in hard-to-reach places, it is better to use an asymmetrical "boat".

Overhead welding is most difficult. This requires experience. The problem is that the melt is trying to drain from the working area. To prevent this from happening, welding is carried out with a short arc, the current is reduced by 15-20% in comparison with the usual values.

If the thickness of the metal at the point of welding exceeds 8 mm, then several passes must be made. The diameter of the first pass should be 4 mm, the subsequent ones - 5 mm each.

Depending on the orientation of the seam, select the appropriate position of the electrode... For horizontal, vertical, ceiling connections, welding of fixed pipe joints, the electrode is directed with an angle forward.

When welding fillet and butt joints, the electrode is directed backward. Hard-to-reach places are welded with an electrode at a right angle.

Welded joint processing

Slag is formed during welding. If slag inclusions get into the seam, its quality deteriorates. All slag layers must be cleaned.

If the welding is carried out with several passes, then the seams are cleaned after each welding step. In this case, any methods are used. First, the welded parts are hammered and cleaned with a stiff brush.

Then a rough cleaning is carried out. Small parts are cleaned with special knives or grinding wheels. Large blanks are cleaned on machines. At the final stage, the welded joint is polished.

Often a fiber grinding wheel is used for this. There are other ways to polish welded joints.

The welding business is constantly evolving. New materials appear, technology improves. It is necessary to follow the news in the welding business in order to learn a lot of new and interesting things.

Today, the following types of electric arc welding are known:

At home, these types of welding are practically not used. Therefore, let us turn to the consideration of the fourth type of welding work - manual electric arc welding.

Manual arc welding is based on the use of a special electrode in the coating

Electric welding machines for manual welding are divided into two types - alternating current and direct current. The use of alternating current allows the design of devices of high performance and power. The advantage of direct current, because there is no polarity reversal, is a smoother weld with less metal spatter.

In 1802 V.V. Petrov discovered the phenomenon of a galvanic voltaic arc.

The device for welding metals using "electrohephaestus" was patented in 1882 by N.N. Benardos.

Russian engineer N.G. Slavyanov in 1888 was the first to use an electrode for welding.

In 1932, the Soviet physicist K.K. successfully welded metals under water.

Repair of a subsea pipeline

The work of the welding machine is based on the creation of an electric arc at the point of contact of two metal parts. High temperature (up to 7000 o C) melts the material to a liquid state and diffusion occurs - mixing at the molecular level.

The fundamental difference between welding and gluing is the absence of auxiliary materials - the parts to be joined turn into a monolithic structure.

Therefore, it must be clearly understood that only homogeneous metals can be used for the correct application of welding. Do not weld aluminum to iron or copper to stainless steel. The melting point of different materials is different, and the creation of alloys is not included in the range of capabilities of welding equipment.

There are various welded machines for welding iron structures.

The main advantage of inverter welding is the improvement in the dynamics of the electric arc, as well as a noticeable reduction in the weight and dimensions of the installation (in comparison with direct transformers). In addition, it became possible to smoothly adjust the output current, which significantly increased the efficiency of the unit and ensured the ease of ignition of the arc during operation.

But there are also disadvantages:

time limitations in use, which is associated with the heating of the electronic conversion circuit;
creation of electromagnetic "noise", high-frequency interference;
Negative influence humidity, which leads to the formation of condensation inside the device.

What is needed for work

Before starting welding, you need a welding machine and equipment:

The place where welding works is carried out is freed from combustible materials and is equipped with fire extinguishing means - water, sand, technical soda. If this is a closed room, it is necessary to equip supply and exhaust ventilation.

Necessary fire-fighting equipment at any facility

How to weld properly

To successfully master the technique of one-piece connection of metal parts, it is necessary to master 4 basic skills, without which not a single "welding session" can do.

Setting up the machine

The basis for setting up the welding machine is the correct selection of the current and voltage output to the terminals. Despite the simplicity of the wording, the topic of customization deserves a separate discussion. But if we briefly formulate the tuning criteria, then we can distinguish 5 main parameters:

In order to accurately select the current value, the easiest way is to use ready-made tables.

But due to the fact that each device has its own design features and technological nuances, the decisive word still remains with the "scientific poke method" - an empirical selection of the required current experimentally.

Setting the welding current depending on the diameter of the electrode

Table of the ratio of the electrode and welding current

Current selection mode for welding standard butt joints:

A one-sided seam connects the surface of the parts on one side, a double-sided seam on two opposite sides.

Examples of welding parts with various seams

You can also use a generic table for a wide range:

It is easy for a novice welder to remember a simple rule. If the current exceeds the required value, the electrode will burn the workpiece. If the current is lower than necessary, the part is not welded, the deposited metal falls off when mechanically exposed to it.

Electrode connection

The electrode can be connected to the positive or negative current output. If a "+" is connected to the part, then the polarity is called straight. If "-" - reverse. Accordingly, with direct polarity, a "minus" is located on the electrode, and with reverse polarity, "plus" is located. The difference between these positions is that more heat is always generated at the positive terminal. Experienced welders use this phenomenon to solve specific problems. So, for example, by manipulating polarity, you can weld thin stainless steel sheet, sensitive to overheating. For this, "plus" is applied to the electrode, and "minus" - to a sheet of thin metal.

One of the options for connecting the electrode

Video: forward and reverse polarity when operating an inverter welding machine

Create an arc

The welding process begins with the ignition of an electric arc. In all types of manual welding, the arc is created by briefly touching the electrode to the workpiece. In this case, there is a sharp heating of the end of the electrode to a temperature sufficient to establish an arc discharge.

The arc ignition process requires certain skills.

After a short circuit, if the arc has ignited, it is necessary to maintain the distance between the end of the electrode and the workpiece 3-5 mm. In this case, it is necessary to take into account the fact that the length of the electrode decreases with welding. When exceeding a distance of 5 mm. the arc is interrupted when the decrease is less than 3 mm. the electrode can stick to the workpiece or cause a large spray of molten metal.

Electrode movement

To create a good seam, various schemes for guiding the arc along the welded place have been developed. In this case, it is considered important not only to melt the edges of the parts to be welded, but also to fill the weld pool the required amount metal deposited from an electrode.

Various options for the trajectory of the end of the electrode

This can be achieved while maintaining a constant length of the electric arc and systematic movement of the end of the electrode along a certain trajectory.

When producing a seam without transverse movements, the width of the joint is usually equal to b = (0.8–1.5) xd el. Where b is the width of the welded joint, and d is the diameter of the electric

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Today, there are many different methods of joining metal products. They can be divided into two groups:

Detachable.
Non-detachable.

Classification of welds.

The connections of the first group include parts that can be disconnected without disturbing the connecting elements, for example, a bolt with a nut. It is the second connection that is the most reliable. In this case, the parts cannot be separated without breaking the connecting part. It is a welding and riveting connection. When you need to get a high-quality and reliable connection, the weld is considered the best. Many people buy welding machines to weld parts, but they have absolutely no experience at all. After several unsuccessful attempts, they have a question: how to put the weld seam correctly? To do this, you need to know a few basic rules.

Main characteristics

The welding process is the joining of metal using electric arc welding. The parts to be joined are melted using an electric arc, as well as an electrode consisting of a metal rod with a special coating. The quality and reliability of a welded seam is influenced by many different factors:

Coated metal electrode welding scheme.

welding machine;
current adjustment;
electrode size;
professionalism of the welder.

The types of welding that are used in everyday life and industry are divided into several groups:

gas press;
contact;
roller;
electroslag;
termite;
friction welding.

When gas pressure welding is used, an open flame of acetyl oxygen is used. The positive side of this method is considered to be high productivity. This method is widely used in the gas and oil industries. It is often found when pipelines are being laid. This method is widely used in mechanical engineering.

Resistance welding takes place at low voltage but high electric current. Using this method, you can cook in a spot and butt method.

Diagram of a semiautomatic welding machine.

To master the technological process of welding production, first of all, you need to have the appropriate welding equipment. You can rent or buy it. Today, stores offer a wide range of welding machines that have a device that makes it possible to adjust the current strength. A home craftsman can make a welding machine himself, but he cannot do without a converter. electrical energy... These devices come in several varieties.

Some types of devices for quality work

Transformer. Designed to generate DC power when you have to use a household outlet. When buying such a unit, you must always remember that inexpensive models are not able to maintain the stable operation of the electric arc. Tension sags very often. The negative side is also their mass, they are heavy and clumsy.

Rectifier. This is a device with the help of which the household current is converted into direct current. The device differs from the transformer in the stable operation of the electric arc. The quality of the weld is quite high.

Inverter. The newest converter that allows you to work on any type of current. Provides always high welding quality. At the same time, the seams are even and smooth. The device is very compact, lightweight and easy to ignite. The inverter features high performance and fast response.

For normal operation of electric welding, there must be a stable burning of the arc. This consistency depends on the correct choice of the gap between the work piece and the electrode coating. The arc burns best when the gap is 5 mm.

Technique for making welded seams.

The high arc temperature causes the workpiece and the metal rod of the electrode to melt. At this time, all the depressions that have formed as a result of melting are poured. With a slow movement of the electrode along the surface of the seam, the voids are poured.

To be proud of the resulting seam, you need to choose the right electrode. To do this, you need to know the composition of the metal of the part that will need to be welded. The selection of the electrode is based on these parameters. There are several types of electrodes. They may be:

steel;
copper;
cast iron;
bimetallic;
brass.

By marking the electrode, you can determine the viscosity of the resulting seam, the numbers will tell about the hardness of the metal. The main rule when choosing an electrode is its size. It must match the thickness of the metal.

For high-quality electric welding, so that the seam looks neat and durable, it is necessary to choose the correct inclination of the electrode. Typically this angle is 75 degrees relative to the direction of the arc. For an arc to appear, you need to strike on the metal surface and, when a flash appears, quickly raise the electrode. When the arc appears, it must be slowly led along the seam. An arc will also occur when the electrode is tapped on the surface.

To obtain a stable burning of the arc, it is required to correctly adjust the amperage. If it is insufficient, the arc will go out very quickly, and the electrode will "stick". When the current strength is large, the metal is spattered in all directions, it starts to burn.

During operation, the electrode melts, it gradually decreases in size. In this regard, you need to constantly move it to the part, maintaining the required distance for a stable arc. If this is not done, the arc will quickly extinguish.

During the welding process, a weld pool is formed, which is a liquid mixture of molten metal and a consumable coated metal core. When there is a constant smooth movement of the electrode with a sustained gap, the quality of the seam will be the most reliable, the mechanical indicators will be at their best. The seams will look aesthetically pleasing.

After welding, slag is formed over the entire surface of the seam.

It is removed with small hammer blows. Then the seam is cleaned with a metal brush. To learn how to cook metal with high quality, you need constant training, the desire to get excellent quality work. Before starting independent work, it is worth seeing how experienced welders work.

Of course, welding is very complex and challenging. It is almost impossible to instantly master all the nuances of this business. It will take a lot of time to master all the tricks of welding. When experience and work skills appear, it will be possible to obtain original and beautiful products by welding.

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Welding of ceiling seams. The sequence of work.

The overhead weld is considered one of the most difficult types of weld because the weld pool is upside down. Welding overhead seams requires a precise sequence of steps. If you do not follow the rules and recommendations, you can get a poor-quality connection, which is fraught with smudges of hot metal.

When performing a ceiling seam, you need to observe safety precautions and protect your face and hands from possible hot drops of metal.

Features of the ceiling seam technique

Note! Preparatory work before welding ceiling seams is accompanied by a number of difficulties. This is due to the fact that during the welding process, the molten metal can flow down and accidentally fall on the skin of the person who is performing the weld. That is why experienced specialists, knowing how to cook such a seam, use special welding techniques that ensure strict adherence to safety rules.

Before joining the ceiling seams, you must clearly understand all the requirements and not neglect the implementation mandatory conditions... This information is especially important for novice welders.

If your workpieces are more than one centimeter thick and you do not know how to cook a ceiling seam, then know that in such a situation, welding should be done in stages. At the very beginning of work, an electrode with a diameter not exceeding 3 mm must be used; at all other stages, an electrode with a diameter of 4 mm is taken.

Note! Welding a ceiling seam implies the creation of not only horizontal seams, but also joints along a certain slope (from 10 to 80 ° C). In this case, it can be used as manual welding and welding with a semiautomatic device. You can also use arc welding with coated electrodes.

As already noted, the main distinguishing feature of such welding is based on an inverted weld pool and holding the glowing metal by the tensile force. It is very important to keep the bath as small as possible and sometimes move the electrode aside so that the metal has time to cool and set. In addition, this welding method will protect your connection from cracking.

Welding methods

Crescent, this method involves the location of the electrode at an angle of 90-140 ° to the surface. With the help of oscillatory movements along the arc, it moves in the direction from edge to edge.
A ladder, here the electrode is placed in the same way. It is taken away from the hot metal and returned back.
Reverse-translational method. In this case, the electrode must be constantly returned to the hardened seam.

The first method is considered the simplest and is well suited for inexperienced welders. Ladder and reciprocating welding options are more complex and time consuming. But such a connection will be of better quality.

Stages of work

Initially, the places that will be welded must be well processed by cleaning the edges with a grinder or a metal brush. Then the root of the seam is welded with an electrode (3 mm). By means of it, a bead of molten metal is formed. If it is necessary that the roller was on the reverse side, then the electrode is directed into the gap with small short throws. Monitor and control the uniform arc burning. The formed bead must be freed from the slag. If its shape is too convex, then it is imperative to bring it to pure metal. As already mentioned, in the next steps, an electrode with a large diameter (4 mm) is used.

In order to obtain a reliable and durable seam, all safety rules must be followed. Compliance with the rules depends not only on the quality of the seam, but also on your personal safety.

Be sure to insulate all wires, and when you pause work, turn off the welding machine altogether. So you protect yourself from electric shock during the welding process.
It is recommended to weld overhead seams in a warm, dry environment.
In no case should you work in rainy and snowy weather. Welding in humid rooms can only be performed by highly experienced specialists, but even in this case, you should be extremely careful.
Wear special protective clothing, mask and goggles. The whole body should be tightly covered with clothing.

In conclusion, it should be noted once again that welding of ceiling seams is a rather laborious and energy-consuming process. It is quite difficult for a novice welder to perform this type of connection. In order to do the job with high quality and create a good durable seam, you need to gain special knowledge, master the technique of working with a welding machine and become familiar with all the nuances of this type of work. Beforehand, it is better to practice welding some parts. If you do not have enough knowledge and experience, then it is better to entrust this process to specially trained people. In any case, both experienced welders and novices alike must strictly follow the safety rules. Accurate adherence to all regulations and instructions is a guarantee of your personal safety.

How to weld by welding correctly. How to put the weld seam correctly

One of the most awkward and difficult welding positions is overhead. But it is worth mastering this type of connection in view of the automatic increase, which has learned to apply high-quality seams in such a spatial position. This is in demand at enterprises whose activities are related to laying, and at construction sites. This skill will come in handy in everyday life, when welding heating or a gazebo. Some elements of a metal garage cannot be assembled without welding joints at the top. How to weld a ceiling seam with electric welding? What are the main precautions and optimal settings for the machine?

Many welders do not like ceiling seams because of the difficulties in their execution. A beginner's result can often be poor, which discourages learning. But if you understand the main problems and prevent them as much as possible, then pretty soon, after training, you can master this difficult connection.

Welding a ceiling seam with an inverter or transformer is significantly different from working on a similar product in the lower position. When the metal is welded on the floor, the weld pool spreads over the joint, and the welder only needs to ensure that the joint is properly filled, avoiding slag in front of the pool. When the ceiling serves as a working surface, the molten metal tends downward under its own weight.

Slag, being in a liquid state, also constantly drips, which interferes with the seam. These splashes, hitting the ground, scatter even more, falling on the welder and surrounding objects. The main difficulty in arc welding in the overhead position of the seam is the connection of the sides of the product. The weld pool is formed on one edge, but it is not possible to tie both sides with metal.

Welding of ceiling seams is carried out at a reduced current, which entails frequent sticking of the electrode and lack of fusion. Another one. The position of the body with the head thrown back and the arm raised up quickly tires the welder. Therefore, frequent breaks are essential to get the job done well. Understanding these complexities will help you to tune in to the difficulties and take steps to facilitate the implementation of the process.

Ceiling welding technology

To figure out how to correctly perform this type of connection, you need to know the basic rules used by experienced welders. Additionally, you can see how to weld a ceiling seam with electric welding in the video. Here are the highlights:

The sides to be welded should be brought together as much as possible. Welding with gaps on the ceiling is available only to experienced professionals, so the tighter the parts are mated, the easier it will be to weld.
Edging is done as in the bottom position. With a side thickness of more than 5 mm, a V-shaped bevel is made.
The electrode is brought up to the ceiling at an angle of 45 degrees relative to the upper plane. Novice welders can try welding with half an electrode, as this will allow better control over the tip and control the formation of the seam.
The welding process and the seam itself in this spatial position are possible due to the surface tension of the metal. To prevent molten iron droplets from flying off, without having time to catch on the edge, the current should be reduced.
If the sides are close together, then the first seam on flat plates can be made without oscillating movements. This will fill the joint well. The second pass is made wider to strengthen the ligament. But on pipes it is better to immediately cook with a wide seam.
Welding with an electrode can be performed in several ways: crescent, horizontal figure eight, or spiral. When there is a small gap, an intermittent arc is applied to cool the deposited metal drop. A moment later, preventing the red color from passing (this can be seen through the mask), the next drop is applied. This is a long process, so the welder does not need to rush and needs to rest periodically.
Do not be intimidated by the type of connection after the end of the work. Slag can flow down in several tiers. But after breaking it off, a high seam should remain. Sagging and large rolls are not critical.

Apparatus and electrodes

Ceiling joints can be made with an inverter or a conventional transformer. It is important to correctly set the amperage, which is 25% lower than when welding on the floor. For example, for plates with a thickness of 5 mm, 100A is sufficient. It will be easier to work if the cable is not heavy. This will make it easier to control the end of the electrode and the hand will be less tired. You can also loop the cable around your arm to reduce stress on your wrist.

Electrodes for ceiling welding are suitable with a diameter of 3 and 4 mm. It is important to reduce the amount of splashing. Using short electrodes for beginners will allow for more confident manipulation of the arc.

Precautionary measures

With overhead seams, you should wear a tight jacket and trousers. Gloves should cover the cuffs, otherwise the scale will roll to the elbows and burn the skin. On the head, a hat or cap without a visor is required. It is important to choose a pair of trousers so that they cover the collar of the shoe to prevent molten particles from entering.

Since the spray will spread further when hitting the ground, there should be no flammable objects nearby. You need to beat off the slag wearing protective goggles, because it will fall down onto the welder. Frequent rest will relieve the load on the muscles of the neck and arm and do the job efficiently.

Welding in the overhead position is not immediately mastered. It takes practice and patience. It is good to set aside a few minutes a day and weld two pieces of pipe or corner to the table and try to weld them from below. Having mastered this method, you can safely cook pipes and metal structures of any complexity.

›How to cook properly with electric welding: weld metal pipes and make beautiful seams.

A weld seam is one of the most reliable ways to join parts. It is used in industry and everyday life. Every home craftsman uses welding from time to time. It is good if he knows how to cook himself, but often he has to turn to specialists. But welding is quite possible to learn. You should start with the simplest: electric welding for beginners is, first of all, learning how to perform various seams. More complex work can be performed only by gaining experience. Let's take a look at the basics of the technology and some of the tricks of the welding process. Where to start - the preparatory stage BEFORE all you need to prepare the equipment. You will definitely need a welding machine, a set of electrodes, a slag hammer and a brush. The diameter of the electrode is selected depending on the thickness of the metal sheet. Don't forget about protection. We prepare a welding mask with a special light filter, tight clothes with long sleeves and gloves, preferably suede. You will also need a welding rectifier, a transformer or an inverter - devices that convert alternating current into direct current necessary for welding. Before work, it is necessary to prepare protective equipment, which includes a special mask with a light filter, suede gloves and long-sleeved clothing, as well as Required tools Welding process technology Welding is a high-temperature process. For its implementation, an electric arc is formed and held from the electrode to the workpiece to be welded. Under its influence, the base material and the metal rod of the electrode are melted. Formed, as experts say, welding

In a private house, in a dacha, in a garage and even in an apartment, there are many jobs everywhere that require metal welding. This need is felt especially acutely during the construction process. Here it is especially often required to cook or cut something. And if you can still cut it off with a grinder, then there is nothing to reliably connect metal parts except for welding. And if the construction is carried out by hand, then the welding work can be done independently. Especially in those places where the beauty of the seam is not required. We will tell you how to cook by welding correctly in this article.

The basics of electric welding

Welded joints of metal today are the most reliable: pieces or parts are fused into a single whole. This happens as a result of exposure to high temperatures. Most modern welding machines use an electric arc to melt metal. It heats the metal in the affected zone to the melting point, and this happens over a small area. Since an electric arc is used, welding is also called an electric arc.

It's not really The right way welding)) At least you need

Types of electric welding

An electric arc can be formed by both direct and alternating current. Alternating current welding transformers are brewed, inverters are constant ones.

Working with a transformer is more complicated: the current is alternating, therefore the welded arc "jumps", the apparatus itself is heavy and cumbersome. There is also a lot of annoying noise that the arc and the transformer itself emit during operation. There is one more nuisance: the transformer strongly "sags" the network. Moreover, there are significant voltage surges. The neighbors are not very happy about this circumstance, and your Appliances may suffer.

Inverters mainly operate from a 220 V network. At the same time, they have small dimensions and weight (about 3-8 kilograms), they work quietly, and have almost no effect on the voltage. The neighbors will not even know that you have started using the welding machine, unless they see. In addition, since the arc is caused by direct current, it does not jump, it is easier to mix and control it. So if you decide to learn how to weld metal, start with a welding inverter.

Welding technology

For an electric arc to occur, two conductive elements with opposite charges are required. One is a metal piece and the other is an electrode.

The electrodes, which are used for manual electric arc welding, are a metal core covered with a special protective compound. There are also graphite and carbon non-metallic welding electrodes, but they are used for special work and will hardly come in handy for a novice welder.

When the electrode and metal, which have different polarities, touch, an electric arc occurs. After its appearance, in the place where it is directed, the metal of the part begins to melt. At the same time, the metal of the electrode rod melts, being transferred with the electric arc to the melting zone: the welded pool.

How a weld pool is formed. Without understanding this process, you will not understand how to cook metal correctly (To increase the size of the picture, right-click on it)

In the process, the protective coating also burns, partially melting, partially evaporating and emitting a certain amount of incandescent gases. The gases surround the weld pool, protecting the metal from interaction with oxygen. Their composition depends on the type of protective coating. The molten slag also covers the metal, helping to maintain its temperature. To weld properly, it is necessary to ensure that the slag covers the weld pool.

The weld is obtained by moving the bath. And it moves when the electrode moves. This is the whole secret of welding: you need to move the electrode at a certain speed. It is also important, depending on the required type of connection, to correctly select its angle of inclination and current parameters.

As the metal cools down, a slag crust forms on it - the result of the combustion of protective gases. It also protects the metal from contact with oxygen in the air. After cooling it is hammered with a hammer. In this case, hot fragments fly away, therefore eye protection is required (wear special glasses).

How to weld metal correctly

Learning how to properly hold the electrode and move the bath is not enough for a good result. You need to know some of the subtleties of the behavior of the metals being joined. And the peculiarity lies in the fact that the seam "pulls" the details, because of which they can be skewed. As a result, the shape of the product can be very different from the intended one.

Electric welding technology: before starting the seam, the parts are connected with tacks - short seams located at a distance of 80-250 mm from each other

Therefore, before work, the parts are fixed with clamps, ties and other devices. In addition, potholders are made - short transverse seams, laid after a few tens of centimeters. They hold the parts together, giving the product shape. When welding the joints, they are applied on both sides: this is how the resulting stresses are compensated. Only after quiet preparatory measures start welding.

How to choose a welding current

It is impossible to learn how to cook with electric welding if you do not know how to set the current. It depends on the thickness of the parts to be welded and the electrodes used. Their dependence is presented in the table.

But with manual electric arc welding, everything is interconnected. For example, the voltage has dropped in the network. The inverter simply cannot provide the required current. But even under these conditions it is possible to work: you can move the electrode more slowly, achieving good heating. If this does not help, change the type of movement of the electrode - passing through the same place several times. Another way is to put a thinner electrode. By combining all of these methods, a good weld can be achieved even under these conditions.

Now you know how to cook by welding. It remains to work out the skills. Choose a welding machine, buy electrodes and a welding mask and start practice.

To consolidate the information, watch the video tutorial on welding.

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