320 MW电站锅炉高压旁路管道接头硬度异常分析

Analysis on Abnormal Hardness of High Pressure Bypass Pipe Joint of a 320 MW Power Station Boiler

某电站锅炉高压旁路管道焊接接头硬度偏高。对硬度异常的焊接接头进行了化学成分分析、硬度检测和金相检验。结果表明:硬度异常区位于弯头侧热影响区,组织为回火索氏体和马氏体,而母材组织为铁素体和贝氏体;此外还发现进行过补焊。正是不正常的显微组织和补焊导致高压旁路管道焊接接头硬度异常。

Hardness of the welded joint of high-pressure bypass pipeline of a power station boiler was on the high side.The welded joint exhibiting abnormal hardness was tested for chemical composition,hardness,and mocrostructure.The results showed that area exhibiting abnormal hardness was located in the heat affected zone at the elbow side,had the microstructure consisting of tempered sorbite and martensite,whereas microstructure of the base metal consisted of ferrite and bainite.Besides,it was also found that the repairing welding was performed.It was the undesirable mocrostructure and the repairing welding that resulted in the abnormal hardness of the welded joint of high pressure bypass pipeline.