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Treatment of Excessively Wide Heat-affected Zone of Small Diameter Thick-walled Pipe Weld

Date:2021-08-16    keywords:small diameter thick-walled pipe, heat-affected zone

In the process of high-frequency welding, especially in the production of thick-walled small pipe diameter products, such as small pipes of 1 inch and below, the wall thickness is relatively thick, usually we will encounter a particularly wide heat-affected zone at the weld , More than 1/3 of the arc surface of the pipe diameter, or even more than 1/2 of the arc surface of the pipe diameter. Lead to the production of waste.


erw steel pipe


How to deal with the above situation, usually we can take the following measures:

1. Increase the welding frequency of high-frequency equipment operation. When we clarify product requirements, we must have requirements for equipment in the selection of equipment rated frequency.
2. The induction coil used is matched with the application of the impedance device, and a reasonable impedance device specification is selected.
3. The coil designed with magnetic conductor avoids the magnetic circuit and ensures that the magnetic field effectively acts on the weld.
4. Improve the welding speed of the high-frequency welding machine, speed up the production speed, and limit the heat diffusion time.
5. Accurately select the coil style, adjust the width of the coil winding material, scientifically and reasonably select the copper tube specifications, and reduce the heating length of the coil.
6. Try to reduce the opening angle as far as possible when the amount of sparks for ignition allows.

The pipe is a product of high frequency welding. When the pipe diameter is small, especially when the pipe diameter is less than 1/2, the wall thickness is very thin, and the wall thickness is 1 mm, the steel strip enters the process of extruding the rod after passing through the high frequency induction coil In the middle, sometimes we encounter the phenomenon that the steel strips on both sides of the triangle area cannot be squeezed.

The reason for this phenomenon:

1. The wall thickness of the pipe specifications is too thin;
2. The overall torsional strength of small pipe diameter raw materials is not high;
3. Higher speed during high-speed welding;

These reasons are the objective factors of frustration in the process of high-frequency welding.

How to avoid this phenomenon? The following measures are recommended:

1. Minimize the space distance between the extrusion rod and the last forming rod (guide rod) immediately following;
2. Adjust the appropriate squeezing force;
3. Minimize the width of the heat-affected zone of high-frequency welding;

4. It is very important to maintain a certain stable tension in the three-dimensional space of the triangle zone steel strip that enters the high-frequency welding zone of the extrusion rod.


Tips: High-frequency welding is a new type of welding process that uses the skin effect and adjacent effect generated by high-frequency current to connect steel plates and other metal materials. The emergence and maturity of high-frequency welding technology is a key process in the production of ERW steel pipe. The quality of high-frequency welding directly affects the overall strength, quality level and production speed of welded pipe products.


The above is a detailed introduction to the treatment of the problem of excessively wide heat-affected zone and frustration of the welds of small-diameter thick-walled pipes. I hope that the above content will be helpful to everyone.

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