Care must be taken for these problems in the welding operation of stainless steel welded pipes

  Stainless steel welded pipe is made of steel or steel strip after crimping by machine and die. The key to the quality assurance of stainless steel welded pipe is the quality of raw materials. Therefore, all raw materials into the factory before use, must be inspected, including: appearance detection, width measurement and thickness is equal; In addition, the chemical composition and tensile test check, qualified before normal production. However, in the actual production of stainless steel welded pipe, often appear this or that problem. So, do you know what are the problems that stainless steel welded pipes are prone to? What are the reasons for these problems in stainless steel welded pipes? Here the author makes a solution with you.

In the welding operation of stainless steel welding pipe factory, the problems that are prone to occur are: unqualified welding seam, incomplete welding or being burned through, cracks and pores. To be specific, it is:

1. Unqualified weld is due to improper selection of welding process parameters or unskilled operation technology. Lead to the high and low width of the weld is different, and then make the shape of the weld is not very good, the back of the weld is concave, causing the weld to weaken too much, so that the strength of the weld is not enough.

2. Incomplete welding or burned through incomplete welding is mainly due to the following reasons: first, the current is too small; Second, the operation technology is not skilled, the welding speed is too fast, the butt clearance is small; The arc is too long or arc is not aligned with the weld. If the welding wire and the base metal are not fused together or the welding metal is not fused locally, the part should be repaired in time. The reason of burning through is mainly due to excessive welding current. The molten pool temperature is too high. The welding wire is not added in time, the strip butt clearance is too large; Welding speed is too slow. These situations will lead to a single or continuous perforation on the weld, so that the strength of the weld is weakened, so as to be burned through.

3. Cracks and pores (1) The problem with high frequency is cracks. According to the different occurrence of cracks, general cracks can be divided into hot cracks and cold cracks. Hot cracks occur because hot cracks with oxidation color are formed along the intergranular boundary at the temperature of liquid metal during solidification or slightly lower than the solid phase line. While cold crack is a cold crack with transgranular property, bright fracture and no oxidizing color that occurs in solid phase transformation, or the presence of diffused hydrogen, and under the action of excessive welding shrinkage stress during cooling. If the use of welding wire is not up to standard, welding high temperature residence time is too long, resulting in oxidation, overheating and excessive growth of crystal size, the material itself is more impurities, or the material itself is easy to harden, but also more prone to crack. (2) Porosity occurs because there are oil stains, oxide skin and rust on the surface of welding parts and welding wires, or welding in a humid environment, or argon gas is low in purity, or argon gas protection is poor, and the molten pool is oxidized at high temperature, splash and other conditions are easy to produce porosity. The above three problems often occur in the welding operation of stainless steel welding tube manufacturers.

Post time: Dec-15-2021