Resistance welded pipes (short pipes) can only occur in specific environments. It also has the following characteristics:
(1) Stress corrosion cracking can only occur in the presence of stress (especially tensile stress). The stress may be applied, residual stress introduced during welding and joining, or expansive stress caused by wedging of corrosion products.
(2) Stress corrosion cracking (SCC) is a kind of hysteretic damage with time varying, which is completely similar to hydrogen hysteretic cracking.
(3) Stress corrosion cracking is a kind of low stress brittle fracture.


Stress corrosion cracking (SCC) is a common cause of failure of chemical and chemical equipment, especially in oil pipelines. Because of the unpredictability of stress corrosion cracking, it is the biggest hidden danger in petrochemical industry.  The necessary condition for stress corrosion cracking is the coexistence of tensile stress and corrosion medium, which is an important condition for stress corrosion.  In industrial equipment such as petrochemical industry and nuclear power plant, most stress caused by stress corrosion cracking is caused by residual tensile stress, which is often superimposed on the working stress. The residual tensile stress mainly comes from the residual tensile stress produced in the welding process of the equipment. At present, welding cooling is widely used to eliminate residual stress after annealing, and welding residual stress is an important process. This method is a waste of energy and easy to produce large welding residual stress. Postweld heat treatment is a new technology to eliminate residual stress. The material is preheated to the post-heat treatment temperature before welding, and the weld is continuously heated during welding to maintain the temperature. After welding, heat it with insulating cotton to cool it slowly. This method can effectively reduce the welding residual stress and improve the stress corrosion resistance of metals.


After welding, heat treatment can effectively reduce welding residual stress. The higher the heat treatment temperature, the better the effect of residual stress elimination. Postweld heat treatment can also effectively improve the corrosion resistance of ERW pipe. The higher the heat after heat treatment, the stronger the stress corrosion resistance.