The bending coefficient of stainless steel refers to the ratio of the minimum bending force required to the strength of the material itself under different material, thickness, and bending radius conditions. It is one of the important indicators to measure the bending performance of stainless steel. In the bending process of stainless steel, it is the ratio of the increase in the bend length after bending to the original length. Generally speaking, the bending coefficient of stainless steel is about 0.33.

1. Inferior thick-walled seamless stainless steel pipes are more likely to fold. Folding refers to various fold lines on the surface of thick-walled seamless stainless steel pipes. This generally runs through the entire longitudinal direction of the product. The reason for the folding is that inferior manufacturers, in pursuit of efficiency, press down too much, produce ears, and fold during the next rolling. The folded product will crack after bending, and the strength of the thick-walled seamless steel pipe will drop significantly.

2. Inferior thick-walled seamless stainless steel pipes are more likely to be scratched, because the equipment and facilities of inferior manufacturers are relatively simple, which is easy to produce burrs and scratch the surface of thick-walled seamless stainless steel pipes. Deep scratches may reduce the strength of thick-walled seamless stainless steel pipes.

3. The surface of inferior seamless stainless steel pipes is more likely to crack. The reason is that the quality of the blanks is poor. Most of them are adobes, which have many pores. The adobes are cracked due to the effect of thermal stress during the cooling process, and cracks appear after rolling.

4. Scarring is easy to occur on the surface of inferior seamless stainless steel pipes because the material of inferior thick-walled seamless stainless steel pipes is uneven, there are many impurities, and generally the equipment and facilities of inferior thick-walled seamless stainless steel pipe manufacturers are relatively backward, which is easy to stick to the steel. These impurities bite the rollers and easily cause scarring.

In the field of stainless steel pipes, there are two main types: stainless steel welded pipes and stainless steel seamless pipes. Stainless steel welded pipes are welded by straight seam welding after the steel strip is curled and formed by the unit and die; In contrast, stainless steel seamless pipes are made of round steel perforated into tube embryos as raw materials and then made by cold rolling, cold drawing, or self-pressing production processes. However, in the process of producing both types of stainless steel pipes, solid solution treatment is required.
Stainless steel pipes
The purpose of solid solution annealing of stainless steel pipes is mainly two: first, to eliminate work hardening, which is conducive to subsequent processing, such as bending and flaring. Through solid solution annealing, the distortion in the lattice is restored, the extended and broken crystals will recrystallize, the internal stress is eliminated, the tensile strength of the steel pipe is reduced, and the elongation is increased.
Secondly, the corrosion resistance of stainless steel itself is restored. Since carbide precipitation and lattice defects may occur during cold working, the corrosion resistance of stainless steel pipes is reduced. After solid solution annealing, the corrosion resistance of stainless steel pipes will be restored to the best state. Typically, stainless steel tubes used in heat exchangers and condensers need to be solution annealed to meet actual application requirements.