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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。
Electron microscopy found that Cr9Mo + A307 (Cr25Ni13) heterogeneous welded joint widely used in petrochemical refining equipment, after long-term high temperature service, the microstructure change from base metal to weld was ferrite + a small amount of carbonization - → ferrite / martensite boundaries → martensite with larger carbides → martensite + austenite → weld austenite + delta ferrite, with austenite / δ ferrite phase interface with a large number of M_ (23) C_6 carbide precipitation. Microhardness tests show that the martensitic and martensitic + austenitic zones have the highest hardness values and the effect of microstructural changes on high temperature performance and lifetime is discussed.