With the continuous advancement of material processing technology, stainless steel pipes are also ushering in new development opportunities. Typical applications include automobile exhaust pipes, fuel pipes, fuel injectors and other automobile components.

When producing stainless steel pipes, flat stainless steel strips are first processed and then rolled into round tubes. After forming, the seams of the stainless steel pipes need to be welded. Since welds will significantly affect the formability of the final part, if you want to meet strict testing standards, you must choose the appropriate welding technology. Gas tungsten arc welding, high-frequency induction welding and laser welding have been widely used in the welding manufacturing of stainless steel pipes.

High frequency induction welding

In high-frequency contact welding and high-frequency induction welding, the power supply equipment and the pressure supply equipment are independent of each other. In addition, both methods can use magnetic rods, which are soft magnetic components placed inside the pipe body, which help to converge the welding flow at the edge of the stainless steel strip.

In both cases, after the stainless steel strip is cut and cleaned, it is rolled up and then sent to the welding point. In addition, a coolant is used to cool the induction coil used during the heating process. A portion of the coolant is then used in the extrusion process. In this regard, high forces act on the squeeze pulley, which prevents the formation of porosity in the welding area. However, using greater extrusion force will result in more burrs. Therefore, specially designed knives can be used to remove burrs inside and outside stainless steel pipes.

Gas tungsten arc welding

Traditionally, stainless steel pipe manufacturers will choose gas tungsten arc welding to complete the welding process. This process creates an electric welding arc between two non-consumable tungsten electrodes. In addition, inert shielding gas is introduced from the spray gun to shield the electrode, form an ionized plasma flow, and protect the molten weld pool. This process enables efficient and repeatable high-quality welding processes.

The advantages of this process are that it is repeatable, the welding process is spatter-free, and porosities can be removed. This is an electrical conduction process and therefore, the processing is slow.

Laser welding

In all stainless steel pipe welding applications, the edges of the stainless steel strip are melted and solidified when clamping brackets are used to squeeze the pipe edges together. But for laser welding processing, it is characterized by its high-energy beam density. The laser beam not only melts the surface layer of the stainless steel material, but also creates a keyhole, resulting in a very narrow weld shape of the stainless steel pipe.

When the power density of laser welding is less than 1MW/cm2, it will not be able to form sufficient energy density to generate keyholes. In this way, the keyholeless process results in a weld profile that is wide and shallow. The high precision of laser welding results in higher penetration, which reduces grain growth and helps improve the metallographic quality of stainless steel materials.