Controlling the strain of weld metal during solidification is one of the effective methods to prevent solidification cracks in weld.In this project,the effects of auxiliary heat or cool sources on the temperature distribution,the tensile strain of weld metal during solidification as well as on the microstructure,hardness of joint are studied with numerical analysis and experimental methods.The results indicate that the auxiliary heat sources can effectively decrease the tensile strain of weld metal during solidification and prevent solidification cracking.Auxiliary cool source can also decrease the tensile strain,but its effect is less than that of auxiliary heat source.Auxiliary heat and cool sources have no distinct effects on the microstructures,hardness and crystal sizes of joints.