Currently, the project is widely used welding cooling after annealing disposal to eliminate remain stress, and remain stress after welding cooling is an important process of attack, this approach not only a waste of power and simple attack a larger weld residual streww. Health streww corrosion cracking is a necessary condition for coexistence of tensile stress and corrosive media, the tensile stress is an important condition for streww corrosion attack.
Stress corrosion of welded pipes in a particular environment as long as the attack ability, heat treatment after welding is a new skill to eliminate residual spannung. Preheated before welding to the data after heat treatment temperature and the welding process, welding pieces continue to insist that the heating temperature, the welding is completed using its thermal insulation cotton so slow cooling. Useful thermal after welding can weld residual spannung decrease, and the heat treatment temperature is higher, the better to eliminate residual spannung. Post-weld heat treatment can also be useful for the progress of welded steel stress corrosion ability, after the heat treatment temperature is higher, resistance to stress corrosion ability and progress more obvious.
Stress corrosion cracking is a low-stress brittle fracture. Stress corrosion cracking is a petrochemical equipment, especially oil pipelines which it is a common cause of failure of welded steel pipe. Due to stress corrosion cracking occurred unpredictability, so the petrochemical industry, the biggest hidden dangers. Spannung corrosion cracking is a necessary condition for coexistence of tensile stress and corrosive media, the tensile stress is an important condition for stress corrosion. In the petrochemical and nuclear industries such as equipment, most of the stress caused by spannung corrosion cracking is caused by the residual tensile stress, it is often superimposed on stress at work. Mainly from the device residual stresses produced during the welding remnant stresses. Currently, the project is widely used welding cooling after annealing treatment to eliminate vestige stress, while cooling after welding remnant stress is an important process, this approach is not only a waste of energy and easy to produce larger welding residual streww. Heat treatment after welding is a new technique to eliminate the remain stress. Preheated before welding the material to a thermal temperature after the welding process and welding pieces of heating was continued to maintain this temperature, the soldering is completed using heat insulation cotton to its slow cooling. This method can effectively reduce residual stress and improve the streww corrosion resistance of metals. Heat treatment after welding can reduce the remnant stress, and thermal temperature is higher, the better to eliminate the residual stress. PWHT welded steel pipe can effectively improve the resistance to stress corrosion, after the thermal temperature is higher, increasing resistance to streww corrosion is more significant.
