What is rebar forging and how is it done?

Considering the ever-increasing price of rebar now, you should think of ways to minimize rebar waste in your project and make the most of the used rebar. One of these methods is rebar forging, which helps you to reuse rebars in reinforcement. To know what welding forging is, how it is done and what are its benefits, don’t miss reading this article.

What is rebar forging?

Rebar forging is a method of welding two rebars together. In this method, the ends of two rebars are made into paste with high heat, and then by applying mechanical pressure, the rebars are glued together to merge into each other. For this reason, forging welding is also called rebar butt welding.

In rebar forging, no electrode or intermediate metal is used for welding, and only the end part of the rebar is heated using oxyacetylene gas to reach a temperature higher than the crystallization temperature. In fact, the connection of rebars in the forging method is created by changing the form and compression. Also, since the base metal is not completely melted in this method, it cannot be included in the category of complete welding methods.

Why has forging replaced other rebar connection methods?

Apart from the forging method, overlap and coupling methods can also be used to connect the rebars to each other. In the overlap connection, a part of the ends of two rebars were placed next to each other and then they were tied together using wire. The national building regulations have prohibited the use of this method due to the lack of full alignment of the rebars and lowering their resistance against periodic forces.

In the coupling connection, the two ends of the rebars are threaded and then they are screwed together inside a metal cylinder called a coupler. The coupling connection also meets all the requirements in the national building regulations, but due to its high cost and time-consuming use, it is not widely used.

Coupling welding is the only method that, while being economical, is compatible with the rebar connection requirements of the National Building Regulations. Of course, according to this regulation, the use of any rebar for welding is not allowed, and the maximum amount of carbon in the corresponding rebar must be less than 0.52%. Accordingly, only A2 grade ribbed bars can be welded by forging method. To identify the factories producing this rebar, “Expert review of the rebar of 4 important factories in IranRead “

What are the advantages and disadvantages of forging welding?

The biggest advantage of forging welding is the possibility of using short and long bars in reinforcement. In recent years, the price of rebar has increased significantly, and if the price of some of its best-selling sizes, such as The price of rebar 14 Check it out, you will find that it is not economical at all to leave out the throw bars. In the following, you will read the advantages and disadvantages of rebar forging:

Advantages of rebar forging:

• Compared to other rebar connection methods, in the forging method, the additional volume at the connection point is less.
• Forging leads to the elimination of overlap and 20-30% savings in rebar consumption.
• An increase in the level at the connection point leads to an increase in resistance at this point.
• Forging welding increases the speed of reinforcement.
• Due to the reduction of the volume of rebar used, the possibility of better vibration of concrete is provided.

Disadvantages of rebar forging:

• It is difficult to control the heat of acetylene gas and this can affect the quality of the weld.
• The forging operation must be done by a specialist whose salary is higher than that of a normal welder and armature band.
• Rebars that are joined together by forging welding are vulnerable to wind.
• When the weather is cold, the quality of the forging weld decreases. For this reason, it is not recommended to use this method in cold regions.
• If the pressure applied on both sides is not the same, the resistance of the connection point may decrease.

How is rebar forging done?

The smoothness and cleanliness of the cross-section of the two rebars on which the forging welding is to be performed is very important. For this reason, you should cut the cross-section of the bars using a special cutter and then wash them using standard detergents. The distance between this stage and the next stage should be small so that the cross section of the rebars does not get rusted and contaminated.

In the next step, the rebars are placed in the holding jaws of the forging machine, and after connecting the two ends of the rebars to each other and adjusting their position, they tighten the fasteners and screws. Then, by using the adjustment screws on the acetylene and oxygen gas capsules, they adjust their pressure and start the heating operation. Oxygen gas pressure should be 5 to 7 and acetylene gas pressure should be 0.5. The heating time should be between 40 seconds and 3 minutes depending on the diameter of the rebar.

After the rebars become a paste, the heat is turned off and using a special application device, pressure is applied to the rebars to stick to each other. This device has several hydraulic pumps and valves that can be adjusted by opening them. Applying hydraulic pressure continues until the rebars cool down.

How is the quality of forging welding checked?

After welding, the quality of welding should be checked using visual inspection and ultrasonic testing. In the visual inspection, attention is paid to the slope of the joint to the body of the rebar. This slope should be gentle and continuous. In the ultrasonic test, sound waves are used to find out the presence of porosity and holes in the joint.

Defects in forging welding occur when gas pressure and heating time are high or when the rebars are not pressed enough.

The use of high-quality rebar is also effective in the quality of forging operations. To buy high-quality rebar from reliable factories, you can go to Aseron website (https://www.asroon.ir) See. Rebar is offered on this site at factory door price. Also, the quality and authenticity of all steel sections in Aseron’s warehouses are guaranteed by its quality control unit.

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