1 Precision welded pipe with small internal burrs:
An important aspect of the quality of precision welded pipe products is the removal of burrs in the weld. Due to the limited space position, the internal burr removal of small diameter welded pipes has always been a technical difficulty in the welded pipe manufacturing industry. Therefore, selecting the appropriate welding method from the welding technology is an effective way to solve the problem. The welding methods for producing small internal burrs are DC welding method and square wave resistance welding method. These welding methods have the characteristics of uniform heating, smooth weld seam, good quality, and small internal burr formation, generally only 0.1 to 0.2 mm.
2 Micro-beam plasma method to produce high-precision ultra-thin wall welded pipe:
The micro-bundle plasma method is used to weld extremely thin-wall welded pipes. The outer weld is bright and smooth, the inner weld is flat and compact, the burr height is no more than 0.031-0.020mm, and the outer diameter of the steel pipe after welding is 0.10-0.23mm, and the wall thickness difference is 0.020. ~0.034mm, after cold rolling, the outer diameter ellipticity is effectively eliminated, the wall thickness difference is 0.002~0.007mm, and the quality completely reaches the level of precision seamless thin-walled tube. After heat treatment, it has the same structure and properties as the seamless tube, and the economical superiority of producing a very thin tube with a seamless tube is much less than that of a very thin tube after cold rolling.
3 High-strength welded pipes for the automotive industry:
In recent years, the automobile industry at home and abroad has promoted lightweight vehicles to save energy, and it is urgent to replace solid parts with high-strength hollow parts. It is technically feasible to develop high-strength welded pipes instead of seamless pipes to meet the needs of the automotive industry. In the development of high-strength welded pipes for the automotive industry, Japan has successively developed series of steel grades such as C-Ti-B, C-Mn-Nb and C-Cr-AI-B, and adopted different heat treatment systems according to different purposes. Such as annealing, normalizing and quenching, tempering, etc. It is used in high strength welded pipes of automobile industry, and its standard strength grades are 561MPa, 637MPa, 980MPa and so on. In addition to high strength, the welded pipe is also required to have high plasticity, good workability, hardenability, toughness and fatigue strength.