How to weld austenitic stainless steel tubes?

Austenitic stainless steel pipe priming layer welding, the past use of manual tungsten arc welding with solid core wire welding method, the tube is filled with Ar to prevent the root of the weld oxidation, to ensure the internal quality of the weld. However, the tube is filled with Ar in the field construction Difficult, equipment, tank joint and long pipe welding when the amount of filling Ar, especially at height is more unfavorable to the construction, and more auxiliary workers, very uneconomical. To solve these problems, to ensure the quality of the weld, in construction, the bottoming layer using flux-cored wire tungsten arc welding (TIG), filling, cover using gas shielded metal arc welding (MAG).

Bottoming welding, welding gun angle, wire angle and carbon steel welding is basically the same.

In the welding process, the welding gun to do circular oscillation, the purpose is to accelerate the separation of iron and slag, easy to observe the molten pool. At the same time, it can increase the heat input on both sides of the bevel of the base material to prevent the appearance of a single side is not fused. When filling the wire, the wire should be sent to the root of the molten pool and pressed down lightly to ensure that the root is melted through and shaped within the root.

The frequency of wire feeding and removal should be faster than that of solid core wire. The distance the wire is removed should be such that the end of the wire is within the argon protection zone to avoid end oxidation.

When closing the arc, the arc pit should be filled. If the arc pit crack, shrinkage and other defects found, should be cleaned up and then welded. To ensure the quality of the weld. Covering welding, welding before paying attention to the nozzle and conductive nozzle is clean, the size of the gas flow is appropriate, clean up the surface of the bottom layer, control the interlayer temperature.

Because the filler, cover layer with gas shielded welding, the length of the wire out of the length of the stability of the welding process has a greater impact, the longer the wire out of the length, the wire resistance value increases, the wire overheating and melting into segments, the result of the welding process is not stable, metal spatter is serious, poor weld formation, the protection of the melt pool is not good; wire out of the length is too short, the welding current increases, the distance between the nozzle and the workpiece is shortened, welding line of sight Not clear, the weld channel is poorly formed, but also make the nozzle overheating, resulting in spatter sticking or blocking the nozzle, thus affecting the gas flow.