4130高压传输管法兰内孔疑似焊接分析

Suspected welding analysis of flange inner hole of 4130 high pressure transmission pipe

通过磁粉探伤、酸液刷涂检测、低倍检验、金相观察和化学成分光谱分析,为4130高压传输管法兰精加工锻件内孔疑似焊接的检测提供了一种分析方法。结果表明,4130高压传输管法兰内孔表面小台阶处存在焊补痕迹,焊缝中存在马氏体、铁素体、贝氏体等组织,并伴有因过热引起的热裂纹、网状渗碳体和魏氏组织,而4130调质状态后的组织属于回火索氏体+铁素体,由此证明不是热处理前进行的焊接,而是精加工过程焊接产生的组织和裂纹。

Magnetic particle detection,acid brushing test,macroscopic examination,metallographic observation and chemical composition spectrum analysis were combined to provide an analysis method for suspected welding in finishing forging inner hole of 4130 high pressure transmission pipe flange. The results showed the suspected welding repair traces existed at the small step on the flange inner hole of 4130 high pressure transmission pipe. There were structures of martensite,ferrite and bainite in the welding line. Moreover,it was accompanied by hot cracks,reticular cementite and Widmanstatten caused by overheat. Whereas the structure in quenched and tempered 4130 steel should consist of tempered sorbite + ferrite. It indicated that the welding was not conducted before heat treatment but during the finishing process which caused the above structures and cracks.