METHOD FOR POST-HEATING TREATMENT OF WELDED PIPE MADE OF 2-PHASE STAINLESS STEEL

摘要

The present invention relates to a method for the heat treatment after welding of the stainless steel pipe, as a main component Cr: 20 ~ 30%, Ni: 4 ~ 10%, Mo: 1.5 ~ 5.0%, N: 0.1 ~ 0.5%, C: 0.01 including to 0.05%, and the balance Fe and part when manufacturing the pipe by a duplex stainless steel having a thickness of 2.5 ~ 3.5mm containing unavoidable impurities in the plasma or tungsten arc welding, a welding heat input 2.4 ~ 10 kJ / cm in, and a protection supplied from the welding torch for the purpose of oxidation prevention and weldability improvement of surface gas 0 nitrogen gas into Ar gas, an inert gas - the temperature of a mixed gas mixture of 10%, and after welding the weld is 1080 ℃ reached to maintain the heat-treated state for more than three minutes, less than 30 minutes, there is an effect that the corrosion resistance is improved.