Mechanical Properties and Microstructure Evolution of 310S Austenitic Stainless Steel Welded Joint at High Temperature
Heat-resistant stainless steel is an ideal material for high level waste liquid solidified container,and the high temperature properties and microstructure evolution of welded joints have an important effect on dimensional stability and service safety for solidified container.The welding joint of 310S austenitic stainless steel is prepared by plasma arc welding technology.The influence of different temperatures(room temperature to 1100 ℃)on the tensile properties of the welded joint and the creep properties of the welded joint at 600 ℃ and 1100 ℃ are studied.The microstructure,fracture morphology,phase composition,element distribution and tensile properties are analyzed by means of optical microscope,scanning electron microscopy,electron back scatter diffraction,transmission electron microscopy and tensile testing machine.The results show that the elongation of the material is the lowest near the sensitization temperature,and large holes appear in the tensile fracture.With the temperature increasing to 1100 ℃,oxidation occurs on the fracture surface.The welded joint has excellent high temperature creep resistance.Twin microstructure is formed in the base metal zone after 600 ℃ creep,ferrite disappears and grain size grows after 1100 ℃ creep.The effects of high temperature and stress promote the precipitation of M23C6 phase at the grain boundary,which weakens the grain boundary strength.The cracks nucleate,grow and expand at the grain boundary,then finally cause the welded joints intergranular fracture.The research results provide reference for.the safety of the high level waste liquid solidifying vessel and enrich the basic data of the high level waste liquid post-treatment.
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