Effectiveness of repair welding without post weld heat treatment of creep damaged 1Cr-0.5Mo and 2.25Cr-1Mo components

摘要

The effectiveness of repair welding in 1Cr-0.5Mo and 2.25Cr-1Mo power generation components has been determined by full-scale component tests (T-JOints).The components,with wall thicknesses up to 70 mm,had been in service for >80,000 hours before SMAW and GTAW-repair without Post Weld Heat Treatment was executed.The main conclusion of the investigation was that,although a PWHT is desirable,it can be omitted because in that condition the residual life of the repaired areas appeared to be >5 years.Howevr,there are strong indications that the creep strength of matching weld metal is too high compared to the surrounding service-aged base metal when a PWHT is omitted.The SMAW process was preferred to the GTAW process.Moreover,it was concluded that the behaviour of repaired headers can only be evaluated by full-size component creep testing and not by uni-axial creep testing.There is,in principle.no need for replica inspections because the creep crack growth under service conditions is very slow,magnetic particle inspection seems to be sufficient.