Therefore, the carbon element in the 304 stainless steel tube can increase the hardness of the stainless steel tube, but as the carbon content increases, the corrosion resistance of the stainless steel tube decreases, and the plasticity becomes worse. The two conflicting laws of influence also allow people to choose from different use requirements.

1. The stainless steel pipe should not be in direct contact with other easily rusty metals, especially carbon steel, and should be isolated by non-metallic materials such as wooden boards.
2. Stainless steel pipe cutting should not use special stainless steel grinding wheel or plasma cutting and water cutting.
3. When stainless steel pipes and stainless steel pipe fittings are welded, the inside of the weld should be filled with chlorine for protection
4. The arc starting, closing and starting adopts the re-welding method. The arc closing should fill the machine pit, and the arc starting must be completed in the groove. It is forbidden to strike and start the arc on the surface of the base material of the pipe and pipe fittings. If defects such as pores and cracks are found at the arc starting and ending points, they should be cleaned up in time.

If the heat treatment process of the duplex stainless steel pipe is improper, it is likely to cause difficulties in the reprocessing of the duplex stainless steel pipe, and the content of F-A cannot be guaranteed to meet the specified requirements. Therefore, we formulate the heat treatment process based on some references and the metallographic structure and mechanical properties of samples at different temperatures. After the heat treatment temperature of the duplex stainless steel tube is higher than 1100 degrees Celsius, the plasticity of the copper decreases significantly, while the strength maintains a higher value. This phenomenon can be considered to be caused by solid solution strengthening of alloy elements in steel. Because after the solid solution temperature rises, the composite table in the steel is more fully dissolved and the composition is more uniform, so the solid solution strengthening effect is more significant, which increases the strength of the steel. When the dislocation in the steel passes through the ordered phase, it will increase the reverse phase boundary, although the strength is increased, but the plasticity and toughness are decreased. In addition, after high temperature, the relative content of F-A in steel changes greatly, and the ferrite content exceeds 65%, which significantly strengthens the effect of ferrite. Since the ferrite plasticity is lower than that of the 7-phase, the plasticity of the steel will decrease at high temperatures. , Its plasticity is also low, which may be caused by the precipitation of a phase and phase in the steel at 950°C. It can be seen from the ferrite isothermal transformation kinetic circle that the x-phase and a-phase precipitate below 950℃, which can increase the brittleness of steel and reduce the plasticity.