12Cr1MoV/TP347H异种钢焊接接头时效过程中界面组织演变

The interfacial microstructure evolution of 12Cr1MoV/TP347H dissimilar steel welded joints with a nickel-based filler metal during aging was studied in detail to elucidate the mechanism of premature failures of this kind of joints. The results showed that not only a band of granular Cr₂₃C₆ carbides were formed along the fusion boundary in the ferritic steel during aging, but also a large number of granular or plate-like Cr₂₃C₆ carbides, which have a cube–cube orientation relationship with the matrix, were also precipitated on the weld metal side of the fusion boundary, making this zone be etched more easily than the other zone and become a dark etched band. Stacking faults were found in some Cr₂₃C₆ carbides. In the as-welded state, deformation twins were observed in the weld metal with a fully austenitic structure. The peak microhardness was shifted from the ferritic steel side to the weld metal side of the fusion boundary after aging and the peak value increased significantly. Based on the experimental results, a mechanism of premature failures of the joints was proposed.

Interfacial microstructure evolution of 12Cr1MoV/TP347H dissimilar steel welded joints during aging

The interfacial microstructure evolution of 12Cr1MoV/TP347H dissimilar steel welded joints with a nickel-based filler metal during aging was studied in detail to elucidate the mechanism of premature failures of this kind of joints. The results showed that not only a band of granular Cr23C6 carbides were formed along the fusion boundary in the ferritic steel during aging, but also a large number of granular or plate-like Cr23C6 carbides, which have a cube–cube orientation relationship with the matrix, were also precipitated on the weld metal side of the fu-sion boundary, making this zone be etched more easily than the other zone and become a dark etched band. Stacking faults were found in some Cr23C6 carbides. In the as-welded state, deformation twins were observed in the weld metal with a fully austenitic structure. The peak micro-hardness was shifted from the ferritic steel side to the weld metal side of the fusion boundary after aging and the peak value increased signific-antly. Based on the experimental results, a mechanism of premature failures of the joints was proposed.