Welding of dissimilar steels is a widely used connection method for super-heater tubes of boilers in power plants. Taking the TP304H/T22 dissimilar steel welded joint with backing plate at the superheater outlet of a thermal power unit as the research object

the formation mechanism and influence of cracks in the welded joint are analyzed through macro measurement

microstructure analysis

EDS energy spectrum detection and tensile test. The results show that

the differences in thermal expansion coefficients of the three substrates and stress concentration are the cause of the cracks of the dissimilar steel weld with backing plate and crack propagation in nickel base weld filler.The weld is the weak link in room temperature tension

while the fusion line and base metal are the fracture parts in high temperature tension.