How to weld thin metal. How to cook thin metal with an inverter

Welding even with the help of an inverter apparatus of thin metal often causes certain difficulties even for experienced welders. The fact is that here you will have to be guided by completely different rules than when connecting elements of considerable thickness to each other.

First of all, it should be noted that it is strictly forbidden to heat thin metal too much, as it will burn through, and holes will appear in its structure. In this regard, when welding fairly thin sheets of metal, the electrode is led as quickly as possible, without deviating it to the side.

Another difficulty associated with welding relatively thin metal is the need to use low currents, respectively, it will be necessary to weld on a short arc. If even a slight separation occurs, the arc will go out. In some cases, difficulties arise even with ignition, so you will need to use devices with good current-voltage properties, the device should also allow you to smoothly adjust the current, especially.

A semi-automatic inverter device allows you to get the highest quality connection, which will be quite strong and durable. If a person does not have enough experience in terms of using semi-automatic welding, then it is best for him to gain some experience in the field of welding thick elements, only after that move on to joining thin metal. The fact is that the thinner the steel, the more difficult it will be to get a reliable seam.

Home positive characteristic semi-automatic welding equipment is their ability to work perfectly at low currents and low voltages.

It is necessary to listen to the experience of professional welders, who recommend that you take care of own security. When welding metals, it is necessary to use a special protective mask that will protect the eyes from damage from too bright radiation.

The thickness of the electrodes for argon welding should not be too large - their maximum diameter will be about 2.5 mm. The inverter allows you to very quickly adjust the current strength. This is done with one handle, and the current will be in the range from 10 to 200 A. The thinner the electrode is taken and the thinner the workpieces to be welded, the lower the current strength will be optimal.

Work technology

In order to properly understand how to cook thin metal with an inverter, you first need to find out what methods of work are. Many professionals recommend holding the electrode at a slight angle to the workpiece. The flanging method is useful here, when the edges of the parts are slightly bent and begin to be connected with the shortest seams every 10-15 cm. After the elements are fixed, you should go along the entire length of the seam from top to bottom.

Welding thin metal with an inverter often leads to burns (especially if the work is done without interruption). To prevent the occurrence of such a defect, the arc can be torn off for one second. After that, it is returned to the same place and carried out a few millimeters further. This method is more time consuming, however, welding of metal parts is better. The molten metal will cool somewhat during the absence of the arc. This will be clearly visible by the change in color of the seam. The main thing in this technology is not to allow the arc to break off too long, otherwise the steel will cool too much.

If it is possible to use a spot weld, then when welding thin parts, it is better to use it. Its essence lies in the creation of small tacks at a short distance from each other, which will hold the parts in one place.

Argon-arc welding will be much easier if a copper plate is placed under the place of the formed seam. The fact is that copper has completely different technological characteristics than steel, in particular, the level of its thermal conductivity is almost an order of magnitude higher than that of steel. If you put it under the forming seam, then it will take most of the heat into itself, while the steel will not overheat.

How to weld galvanized sheets?

Galvanized or galvanized steel is a thin sheet of metal that has been dipped in an element such as zinc during the manufacturing process. If it becomes necessary to join such elements, then the zinc coating on the edges to be welded will need to be completely peeled off. Do this in one of the following ways:

Remove the layer mechanically - using an angle grinder and an abrasive disc, a metal brush or sandpaper;
Burn out by welding - zinc evaporates at a temperature of about 900 degrees, so you need to pass the electrode twice along the formed seam. However, in this case, it must be remembered that zinc vapor is extremely toxic, so such work can be carried out either outdoors or in a room with good ventilation.

After each pass with the electrode, the flux must be removed from the surface of the workpiece. When the zinc is completely removed, the metal itself begins to be welded. To get the best connection, you should use two types of electrodes.

The basis of the seam is made on the basis of a material with a rutile coating, they need to form the seam as carefully as possible, avoiding too strong fluctuations. The facing seam should be made much wider. For this, standard electrodes with a conventional coating are suitable.

How to choose polarity?

To get a reliable welded joint it is necessary to correctly select such a parameter as polarity, and it can be direct or reverse:

Direct polarity provides a not too high temperature, and heat will pass into the thickness of the metal into a narrow but deep region;
Reverse polarity provides for a higher temperature, and the melting area will not be too deep, but very wide.

To know how to weld thin metal, you need to choose this parameter very carefully. If you put a positive charge on the workpieces to be welded, then they will heat up most strongly. When a positive element is connected to the conductor, the electrode will heat up too much, which ultimately can lead to burn-through of the workpiece.

It is advisable to use reverse polarity when connecting thin metal elements - in this case, it will be possible to obtain the optimal current strength, which will allow you to monitor the formation of the weld and keep this process under direct control. If this process is set up as correctly as possible, then in the end it will be possible to obtain a strong connection without burns through the workpiece and other defects. During welding, the electrode should be moved as slowly as possible. Then the final result will be satisfactory.

To connect metal parts, a large number of devices and welding methods are used. But, when it comes to connecting thin (less than 2 mm) workpieces, then not all methods and devices are suitable for this purpose. Such metal is also called "thin sheet". It is used in many areas such as:

automotive, shipbuilding, aircraft and rail transport;
all kinds of hull structures;
cladding parts of buildings

Sheet metal welding has not bypassed home craftsmen and craftsmen. Due to the fact that welding inverters have become quite widespread in everyday life, a reasonable question arises: is it possible to weld thin metal at home using an inverter welding machine? In this article, we will try to figure out how to properly weld metal with an electrode, find out the subtleties and nuances of this process.

If you are inexperienced in welding thin metal, it is better to familiarize yourself with the technology and features first. Before welding the parts you need, practice on unwanted residue or on a defective workpiece. Then it will be seen how the melting metal of the electrode behaves, and how the arc holds. In inverter welding, only a small current is used, because the working gap between the electrode and the workpiece cannot be interrupted. For any type of welding, you need protective equipment and clothing: heat-resistant leather gloves, rough non-flammable clothing, a welding helmet or goggles, preferably boots with thick rubber soles.

The sequence of work performed when welding with an inverter machine

Preparation for work

Not everyone knows correctly how to cook thin metal with an inverter. Therefore, below is step-by-step instruction for beginners It describes the sequence of work when welding thin metal by electric arc welding:

We select the electrode and the value of the welding current. Often, the current strength for different metal thicknesses is written on the body of the welding machine. The optimal value will be 35-40 A. We select electrodes for welding thin metal according to the table
Now we put the selected electrode in the holder, clamp the ground terminal on the workpiece to be processed.
It is important to note that the parts to be welded must fit snugly against each other.

Work process

Welding begins with a spot tack electrode for welding thin metal along the edges, then a point is made in the center of the future seam. So the metal does not have time to warm up and the internal stress is distributed evenly. The points are made with short movements.
After each application, the welding area must be cleaned with a metal brush to remove traces of slag.
The process of applying dots continues until they begin to overlap each other, while the seam becomes continuous. It is important not to rush and let the metal cool after each pass with dots, then the metal does not warp and the geometry of the product is not disturbed.
After the spot seam has become continuous, for tightness, you can go through it with a continuous seam on a very short arc, resting the electrode on the coating and you need to lead quickly enough.

Experienced welders advise tilting the surface to be welded relative to the horizon and leading the weld from bottom to top. The seam must be “pulled”, in which case the slag will drain and be blown out by the pressure of the welding arc.

The main disadvantage in welding thin-layer metal products is the high probability of burning, deformation and damage to the metal. The main reason is the inaccurate work of the welder, subsequently a damaged product.

From the foregoing, we can conclude that high-quality arc welding with an electrode of thin sheets of metal can be only with a thorough study of the features of the process and properly selected equipment. It is possible to make the necessary arc for welding only by an experienced welder who has already filled his hand and found the required current value.

In industry, in the manufacture of a variety of parts, welding of thin metal with an electrode is very often needed. This question remains today one of the most problematic for beginners to perform welding work as well as for experienced welders. We have to weld a variety of products. For example, body passenger car mostly consists of thin steel sheets. Basically, the use of thin sheet metal concerns issues of profitability of production.

Welding is used to join different metals.

Basic Requirements

It is natural that this species welding requires special approach, several special technological requirements apply to it.

When such a metal is welded, it is very important to use the appropriate electrode. The size of the electrode, its value is directly dependent on the thickness of the sheet metal. For steel sheet having a thickness of 3 mm, welding work must be performed with a 3 mm electrode. For thinner sheet metal, very thin electrodes are specially selected. For example, when a sheet thickness reaches 2.5 mm, an electrode of the same diameter is required.

When welding thin metal, it is necessary to have a welding current supply of a certain value. This parameter depends on two values:

current;
electrode size.

When 3mm steel plate is welded, the welding current is usually made more than 140A. When an extremely thin electrode is used, it is necessary to reduce the welding current. Usually set to 50 A.

Another important parameter when working with thin metal is the type of electrodes used. The small thickness of the metal requires a small current, it needs electrodes that have a coating that makes it easy to get a spark and burn it evenly. The melting of such electrodes must occur very slowly. During the welding process, the metal should become fluid.

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Semiautomatic welding: nuances

Most often today you can find a semi-automatic welding machine. This tool has been specially designed for welding thin sheet metal. The most recognized is the inverter.

Different electrodes are used to weld different metals.

A semi-automatic does this very easily. Since it has a special adjustment, it is able to supply a very small current. This operation depends on:

filler material feed rate;
current strength.

However, as elsewhere, practice and experience come first. The semiautomatic device allows continuous welding, when the seam is smoothly carried out over the entire surface of the part. He has the ability to perform spot welding. When using a semi-automatic device, you do not need to tap the electrode on the metal, just press the toggle switch at the right time.

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Basic information about the electrodes used

There are a lot of varieties, sizes and coatings of electrodes today. To carry out welding at low current, electrodes with a special coating are used. It helps the quick appearance of a spark, maintains stable combustion. Such an electrode has a slow melting and forms a liquid metal. As a result, the seam has a beautiful appearance.

These requirements are fully met by the OMA-2 electrode. Its coverage is:

titanium concentrate;
ferromanganese ore;
flour.

In addition to the above substances, the coating has other additives that provide stable arcing. This is exactly what is needed when welding thin metal.

Electrodes of the MT-2 brand also have similar properties. They are also easy to weld especially thin metal. But, unlike OMA-2, welding work should be carried out only with direct current, moreover, with reverse polarity. When the thickness of the welded metal sheets exceeds 1 mm, it is allowed to carry out alternating current welding.

Thin steel sheets are well cooked by gas welding.

It turns out a very high-quality seam, which is much superior to the seam obtained by electric welding. But, it should be noted that if you have an inverter, you do not need to specifically purchase gas welding equipment to make one seam. Uneconomical and inefficient. With a certain experience and skill, you will get a good seam when using electric welding.

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To perform welding work you will need:

Overlap welding is done by overlapping sheets of metal. The size of the overlap depends on the condition of the edges. The smoother they are, the smaller the size of the overlap. It is desirable that the size of the overlapping sheets exceed 5 mm.

Sheets should be in close contact with each other. To do this, use clamps, clamping brackets or heavy pressure weights. The sheets should not have any gap between them, as this can cause the top sheet to burn through.

For the welding operation, a certain value of the welding current must be set. This value depends on:

electrode size;
sheet thickness.

When the steel sheet is less than 1 mm thick, the welding current parameter must reach 40 A. A much lower current is used for electrodes with a diameter of 2 mm. When the diameter is 3 mm, the current increases.

Before you start serious work, you need to practice a little on a sheet of metal of a similar thickness. Thanks to this, it will be possible to determine the optimal value of the welding current. It is directly dependent on the mains voltage and the values set on the device. During test welding, it will be possible to develop a certain manner so that there is no burn through of the metal. The fact is that you will often have to extinguish and re-ignite the arc. If you delay a little with the removal of the electrode, a hole in the metal will definitely appear.

The sheets to be welded must first be grabbed together. To do this, small seam jumpers are made. Usually their size does not exceed 10 mm. The spacing of the jumpers is 50 mm and is made along the entire butt length. The welding process must be interrupted periodically. The electrode is pulled back to extinguish the arc, then quickly re-ignited, in such moments there will be no cooling of the metal. The magnitude of the current and the size of the thickness of the metal affect the time at which continuous arcing is observed. The arc burns for approximately 3 seconds when the metal thickness is less than 1 mm.

Having worked out certain skills, you can begin to perform the main technological welding process. Sheets must be completely welded. For this, welding is done with an intermittent seam. To obtain such a seam, the electrode periodically moves to the cold part of the joint. As a result, the metal will not begin to warp, especially when the joint has a length exceeding 200 mm. When the continuous seam is short, buckling is minimized. Welding must be started from the end of the joint, gradually moving to the other side, then to the middle, etc.

It is possible to weld very thin metal sheets using the butt welding method. For such an operation, it is necessary that the edges of the sheet have a minimum clearance relative to the total length of the joint. The best is the absence of any gap. In order to butt-weld thin sheet metal, a special auxiliary lining is installed from below. This is necessary, since without a lining to carry out welding work with a very thin sheet metal quite difficult. True, if there is a welding inverter, excellent electrodes, imported production, then such a weld is quite acceptable.

Today, the time has come when the welding of thin metal has become a very important moment in the life of every person. All modern cars Appliances and much more are made using thin metal. And last but not least is the economy. Use thick metal it's just not cost effective.

Therefore, in order to weld thin metal, specialists and craftsmen are needed. It is very difficult to weld thin metal, this is a very complicated process, since any mistake entails burning through the metal and, as a result, a damaged part.

Thin metal can be welded in a variety of ways:

manual electric arc;
continuous;
intermittent;
semi-automatic;
gas.

Welding thin metal: what are the difficulties of work

The main problem of working with especially thin metal is the thinnest edge associated with metal burn-through, with the occurrence of electrode sticking.

Sometimes it does not stick, but another defect appears, the so-called lack of penetration.

When the welding current is adjusted incorrectly, for example, its value is too high or the electrode is delayed in one place, the metal is burned through.

At a low current value, lack of fusion is formed, parts do not weld, they fall off, sticking may occur.

If the current is insufficient, an increase in the distance between the parts to be welded and the electrode leads to an arc break.

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Welding modes and electrodes

To weld thin metal, small diameter electrodes are needed. Usually it does not exceed 4 mm. In this case, the current value should be in the range of 140-180 amperes. These dimensions apply when the thickness of which is 3 mm. To cook metal much thinner, electrodes are used in the range of 0.5-2.5 mm. The current value is in the range of 10-90 amperes.

To carry out welding operations, when applying low current, it is required to use electrodes with a special coating. With its help, there is a rapid excitation and normal burning of the arc. Such electrodes melt very slowly, they get a liquid metal, because of which the seam gets a beautiful look.

All of the above requirements fully comply with "OMA-2". It includes:

titanium concentrate;
ferromanganese ore;
flour;
special additives.

All these substances ensure the stability of the arc. This is simply necessary when thin material is cooked.

The type of electrode "OMA-2" is considered the best for working with thin material. It can create a stable arc used in welding carbon steel parts.

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Technological process

Cooking thin metal with ordinary manual arc welding is quite difficult. To exclude continuous burns over the entire length of the welded ends, a certain technology is used:

electrodes of small diameter are selected;
the smallest welding current is set;
in order for the welding arc to have stable burning, high-frequency currents are used. For this purpose, an oscillator is connected.

A connection is selected in advance, in which burns are completely excluded.
When the thickness of the metal sheet is thinner than 2 mm, the best electrode is the one whose diameter does not exceed 1.6 mm. It must be properly covered. The value of the welding current is adjusted so that it is enough to melt the electrode. Usually it fluctuates in the range of 50-70 amperes. Using an oscillator, a normal arc is obtained. The device helps to quickly get the arc, it eliminates the occurrence of burns.

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Inverter and thin metal work

After the advent of welding inverters, the welding operation has become available to almost anyone. Previously, they used devices that were very difficult to work with, they had a lot of weight and complex settings. Welding with an inverter is very simple, it does not cause any difficulties and is accessible to a beginner. You just need to know a few basic rules.

When inverter welding is performed, a balance is sought in which no burn-through should occur and no sticking of the electrode should occur. In other words, the efficiency of welding directly depends on:

gap between the metal surface and the electrode;
current strength;
electrode movement speed;
smooth running.

All these factors are the most difficult for those who first started welding. In this case, it is very important to have a good eye, specific skills. The more you cook, the better it gets. Only the skills acquired in the process of work will help to achieve success and get a good result.

It is difficult for an inexperienced welder to quickly set the desired current strength on the inverter in order to eliminate metal burn-through and get a reliable connection.

Cooking thin metal with an inverter is far from an easy task. It is difficult even for an experienced master. Therefore, in most cases, argon-arc is used. It allows you to minimize the occurrence of burn-through, the seam is smooth and has a beautiful appearance.

However, pulsed welding is not always possible; you have to weld with an inverter. To get a good result, you can use the recommendations of experienced welders.

Welding sheets of thin metal with an inverter allows you to quickly and efficiently produce a metal product.

Thin-sheet material is called a material with a thickness of up to 5 mm, it is often used in the production of blanks for cars, motor boats, as well as for the manufacture of pipes, various hull structures, etc.

The main problem when welding thin sheets of metal is the high probability of their damage.

The reason for this may be the careless movement of the welder, as a result of which a burn may form on the workpiece.

In addition, welding of thin metal, carried out by a person without experience, may turn out to be of poor quality due to non-compliance with the technology.

Since the welding process is carried out exclusively by the inverter using low current, even a slight gap in the working distance between the workpiece and the electrode must not be allowed.

Otherwise, an arc break cannot be avoided. Therefore, it is not recommended to start welding thin sheets with an inverter without knowledge of the process features.

Welding thin metal requires, like any other welding process, to have protective clothing on hand: a special welding helmet, gloves and outer clothing made of coarse fabric, but in no case should rubber gloves be worn.

Step one

We carry out the setting of the welding current and select an electrical conductor that will allow you to work with an inverter.

We take the welding current indicator based on the characteristics of the metal sheets being joined.

Usually, the manufacturer indicates the current strength for specific cases on the inverter case.

We use electrodes for inverter arc welding with a diameter of 2-5 mm. Next, we insert an electrical conductor into the holder, connect the ground terminal to the workpiece.

To avoid sticking, do not bring it to the part too sharply.

step two

Welding of thin metal using an inverter apparatus begins with the ignition of the arc.

We touch the line to be welded at a small angle with the electrode a couple of times, which will activate it.

We hold the electrical conductor at a distance from the workpiece to be welded, which will correspond to its diameter.

Step Three

If all of the above is done correctly, a high-quality seam connection should be obtained.

At the moment, there is scale or scale on the surface of the weld, they must be removed with the help of some object, for example, a hammer.

The following video for beginner welders will demonstrate how to properly connect thin sheets of metal with an inverter.

How to control the arc gap?

The arc gap is the distance formed during welding between the elements to be joined and the electrode.

Be sure to maintain a stable size of the specified distance during the operation of the inverter.

If you cook thin metal with an inverter and at the same time keep a small arc gap, then the welded seam joint will be convex for the reason that the main part of the metal does not warm up well.

If you cook thin metal with an inverter semiautomatic device and at the same time keep too much distance between the electrical conductor and the workpiece, then such a large gap can interfere with penetration.

The electric arc will bounce, the weld metal will lie crooked.

The correct and stable distance will make it possible to obtain a high-quality seam connection, while it is necessary to weld thin metal with an inverter, as mentioned above, with a gap corresponding to the diameter of the electrode.

Having gained experience and the ability to control the inverter arc length, it will be possible to achieve optimal results.

Due to the electric arc, which is fed through the gap and melts the base metal, a weld pool is formed. It also moves the molten metal into the weld pool.

Features of the formation of the weld

If during the welding process the movement of the electrode is too intense, then all that can be achieved is a deformed joint.

This fact is explained by the fact that the line of the weld pool is below the level of the base metal, and if the penetration of the arc into the base metal is strong and fast, it pushes the pool back, as a result, a seam appears.

That is why it is necessary to control that the welding seam line is located on the surface of the metal sheets.

It is possible to achieve a high-quality seam due to circular and zigzag movements of the electrode along the surface to be joined.

With zigzag actions, it is necessary to monitor the formation of the seam line alternately in three positions: from one edge, from above the weld pool, from the second edge.

Here, one should not forget that the weld pool moves with heat, which is very important when changing the working direction.

With a lack of electrode metal, an undercut is formed - a narrow groove in the base metal along or along the edges of the weld, appears as a result of a lack of metal to fill the bath during transverse movement.

In order to avoid the formation of such a lateral recess or undercut, it is recommended to monitor the outer boundaries and the weld pool, if necessary, adjust the groove width.

Operate the weld pool allows the force of the electric arc located on the tip of the conductor.

Do not forget that when working with a welding product at an angle, the bath will not stretch, but will push.

Therefore, a vertically located electrical conductor allows you to get less convex welding joints.

The process is explained by the fact that at this time all the thermal energy is concentrated under the electrode, the weld pool is pushed to the bottom, melted and distributed around.

With a slightly inclined position of the product, all the force is repelled back, as a result, the weld pops up.

If the electrode product is tilted too much, the force is transferred in the direction of the suture line, which does not allow effective control of the bath.

To achieve a flat seam connection, apply the slopes of the electrical conductor at various angles.

In this case, welding should begin at an angle of 450, which will make it possible to control the bath and correctly connect the metal with a semi-automatic device.

Welding of thin sheet metal with a consumable electrode

In order for the process of welding thin metal with a semiautomatic device to be successful, it is necessary to use an electrical conductor with a suitable diameter.

For example, for sheets of thin metal with a thickness of up to 1.5 mm, products with a diameter of 1.6 mm should be used.

Correctly welding thin metal with a consumable electrode means preventing overheating during the welding process, which can lead to burning in the product.

The electrical conductor is moved along the line to be welded at an average speed, as soon as there is a risk of combustion, the speed is increased.

The current strength during inverter welding of metal sheets should not exceed 40 amperes.

When choosing the current strength for working with a consumable electrode, it is better to make a test weld, which will simplify the solution of the task.

At the same time, on a test product, it is possible to cook semi-automatically in different modes, taking into account the speed of movement of the electrode.

It is necessary to cook in such a way that it is possible to fully ensure the penetration of the steel edges and at the same time not burn through the material.

A feature of welding thin metal with a consumable electrode inverter is the instantaneous melting of the edges, which does not allow you to fully monitor the weld pool.

That is why it is better to start semi-automatically cooking thin sheets of material after gaining experience.

In the process of welding thin sheet metal products, spot or intermittent welding technology can be used.

Due to the short functioning of the arc, tacks are formed, subsequently the electric arc is extinguished, then the process is repeated at a distance equal to the size of 2 or 3 electrode diameters.

The period between the creation of points is best minimized so that the molten metal does not have time to cool.

This method is ideal if you need to weld leaky structures made of thin sheets with an inverter. Spot grips will eliminate possible risk warpage of metal.

How to choose the polarity when working with an inverter?

Polarity is the basis of a good welded joint. Direct polarity provides for a reduced heat input to the base metal with a narrow but deep melting area.

With reverse polarity, a reduced supply of thermal energy to a material with a wide and shallow melting area of the base metal is observed.

It is the polarity of the electrons that must be paid attention to before starting work with the inverter.

If you cook metal at direct current, then you can use the positive and negative charge of the source.

But at the same time, you need to know where to connect which charge.

Here it is necessary to take into account, if the material being welded is provided with a positive charge, then it will be very hot.

If this charge is connected to an electrical conductor, then the electrode will get very hot and burn, which can lead to burning of the metal.

The way out is the reverse polarity of the inverter and the optimal current strength.

In the process of working with an inverter, the electrode is connected "+" to the inverter arc, and "-" to the sheet of metal.

A few of the following tips and thematic video material will also be useful for novice welders:

The ability to observe the weld and control it from all sides in the process of arc welding with an inverter will allow you to get a high-quality result and eliminate the formation of burnt holes;
During welding, the electrical conductor must be kept as close as possible to the product until a red spot begins to appear. This will mean that there is already a metal drop under it, due to which the metal sheets are connected;
When the electrodes move slowly over the metal surface, hot metal drops that appear connect the sheet segments and thereby form a welding seam.

After studying the above information and watching the videos, it will be much easier to weld thin sheets of metal with an inverter.

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