Analysis on Microstructure and Mechanical Properties of T22/TP304H Dissimilar Steel Welded Joint with Backing Plate
Dissimilar steel welded joints are widely used in the boiler structure of thermal power plants,and the analysis of the joints containing cracks in service is the basis to evaluate the safety of dissimilar steel welded joints.With the help of metallurgical microscopy and scanning electron microscopy,the morphology of a T22/TP304H dissimilar steel welded joint with backing plate containing cracks was analyzed,and the welding material was nickel based alloy.The microhardness tester and universal tensile testing machine were used to test the microhardness and tensile properties of the welded joint respectively.The results show that the microstructure of the weld is mainly austenite,Nb(C,N)precipitation phase and M23C6 carbides.There is an obvious fine grain strengthening effect at the fusion zone of T22 side,and the hardness value of the region increases.Austenite grain coarsening phenomenon is not obvious at the fusion zone of TP304H side.There is a significant deterioration of tensile properties of the welded joint at room temperature and high temperature.
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