The surfacing is conducted on nickel-base alloy 690 layers on the low alloy steel（SA508-3） by using the temper bead technology to prepare the specimens. The microstructures of the heat-affected zones（HAZ） corresponding to the different layers of specimen are researched. The results show that the martensitic transformation of HAZ is found after the first layer surfacing by using welding technology in this paper. The martensite temper transformation occurs in the welding thermal process of follow-up surfacing layers

and the transformation effect accumulates as the layer increases

finally the bad quenching microstructure of HAZ is corrected completely. Because of insufficient temper caused by insufficient cumulative time of high-temperature temper in the area near by the toe of weld at the both ends of the specimen

the martensite produced in HAZ by the first layer surfacing and the martensite generated by the decomposition of residual austenite in HAZ are corrected incompletely

but this problem can be resolved by the additional welding with specific technology.