XRD and TEM analysis of microstructure in the welding zone of 9Cr�??1Mo�?�V�?�Nb heat-resisting steel

[摘要] Under the condition of tungsten inert gas shielded welding (TIG) + shielded metal arc welding (SMAW) technology, the microstructure in the welding zone of 9Crâ€�??1Moâ€�?�Vâ€�?�Nb (P91) heat-resisting steel is studied by means of X-ray diffractometry (XRD) and transmission electron microscopy (TEM). The test results indicate that when the weld heat input (𝐸) of TIG is 8.5 ∼ 11.7 kJ/cm and the weld heat input of SMAW is 13.3 ∼ 21.0 kJ/cm, the microstructure in the weld metal is composed of austenite and a little amount of ð›�? ferrite. The substructure of austenite is cryptoâ€�?�crystal martensite, which included angle. There are some spot precipitates in the martensite base. TEM analysis indicates that the fine structure in the heat-affected zone is lath martensite. There are some carbides (lattice constant, 1.064 nm) at the boundary of grain as well as inside the grain, most of which are Cr₂₃C₆ and a little amount of (Fe, Me)₂₃C₆.

[学科分类] 材料工程

[关键词] Heat-resisting steel;welding;fine structure.