利用钨极氩弧熔覆技术在45钢上堆焊了由工作层和M2过渡层组成的铁基梯度熔覆层，研究了梯度熔覆层的显微组织、热膨胀性能、显微硬度、残余应力和抗热震性能，并与单一熔覆层的进行了对比。结果表明：与单一熔覆层相比，梯度熔覆层结构致密无孔洞；单一熔覆层的截面硬度在距表面2 mm时突然降低，而梯度熔覆层截面硬度由表面向基体呈梯度降低；梯度熔覆层热膨胀系数匹配度更优，截面残余应力更低，抗热震性能更好。

Fe-based gradient cladding layer composed of working layer and M2 transition layer was cladded on 45 steel by tungsten argon arc cladding technique. The microstructure, thermal expansion property, microhardness, residual stress and thermal shock resistance of the gradient cladding layer were investigated, and compared with those of the single cladding layer. The results show that compared with the single cladding layer, the structure of the gradient cladding layer was compact with no hole. The cross section hardness of single cladding layer suddenly decreased when it was 2 mm from the surface, and the cross section hardness of gradient layer suddenly decreased from surface to matrix. The matching degree of thermal expansion coefficient of the gradient layer was better, and the cross section residual stress was lower; also, the thermal shock resistance was better.