Cr9Mo钢异类焊接接头高温服役后的显微结构研究

Microstructural study of dissimilar welded joint of Cr9Mo steel after elevated temperature service.

电子显微观察发现,广泛应用于石化炼油设备中的 Cr9Mo+奥307(Cr25Ni13)异类焊接接头,经长期高温服役后,从母材至焊缝的显微组织变化规律为铁素体+少量的碳化物—→铁素体/马氏体边界—→含有较大碳化物的马氏体层—→马氏体+奥氏体—→焊缝奥氏体+δ铁素体,其中奥氏体/δ铁素体相界面上有大量的 M_(23)C_6碳化物析出。显微硬度的测试显示马氏体层和马氏体+奥氏体区具有最高的硬度值,并讨论了组织变化对高温性能与寿命的影响。

It was found that when the dissimilar welded Joint of Cr9Mo and A307 widely used in petrochemical and oil-re fining equipment was used in elevated temperature service for a long time,the change law of the microstruetural com- position from the mother material to the weld seam was as follows:ferrite+a few carbides→ferrite/martensitie inter- face→martensitic layer with a litter more carbides→ martensite+austenite→austenite in weld seam+δfer- rite,and a lot of M_(23)C_6 carbides was separated from the phase boundary of austenite/δ ferrite.The tested micro hardness showed that there was the highest hardness value in martensite layer and the martensite+austenite zone,the influence of composition change on elevated temperature performance and service life was discussed.