Heat treatment on the corrosion resistance of electric-resistance welded pipe after welding

Electric-resistance welded pipe(short for erw pipe) can only occur in a specific environment, it also has the following characteristics:
(1) Stress corrosion cracking can only occur when stress (especially tensile stress) is present. This stress can be an applied stress, or the residual stress introduced during the welding and joining process, or the expansion stress caused by the wedging action of the corrosion product.
(2) Stress corrosion fracture is a time-dependent hysteresis damage, which is completely similar to hydrogen lag cracking.
(3) Stress corrosion cracking is a low stress brittle fracture.

Stress corrosion cracking is a common cause of failure of the chemical and chemical equipment, especially the erw pipe for oil pipelines. Due to the unpredictability of stress corrosion cracking, it is the biggest hidden danger in the petrochemical industry. The necessary conditions for stress corrosion cracking are the coexistence of tensile stress and corrosive media, which is an important condition for stress corrosion. In the petrochemical and nuclear power plants and other industries equipment, most of the stress corrosion cracking caused by the stress is caused by the residual tensile stress, it is often superimposed on the work stress. Residual tensile stress mainly comes from the residual tensile stress produced by the equipment during the welding process. At present, the extensive use of welding cooling after annealing to eliminate residual stress, and welding after the residual stress is an important process, this approach is a waste of energy and easy to produce large welding residual stress. Post-weld heat treatment is a new technique for eliminating residual stresses. The material is preheated to the post-heat treatment temperature before welding and the weld is continuously heated during the welding process to maintain this temperature. After the welding is completed, it is warmed by the heat-insulating cotton to cool it slowly. This method can effectively reduce the welding residual stress, improve the metal's resistance to stress corrosion.

After welding, the heat treatment can effectively reduce the welding residual stress, and the higher the heat treatment temperature, the better the residual stress elimination effect. After welding heat treatment can also effectively improve the resistance of the erw pipe corrosion resistance, the higher the heat after the heat treatment, the more significant resistance to stress corrosion.

Hunan Standard Steel Co., Ltd is a leading seamless pipe and welded pipe manufacturer & supplier serving diverse industries with multiple types, grades, diameters and lengths of pipe.