Abstract:The effects of bipolar aging heat treatment on the microstructure and mechanical properties were studied on GH738 alloy repaired by laser deposition repair technology.The results show that :the microstructure of repair area present typical characteristics of the epitaxial growth of columnar crystals and the dendrite spacing is about 10μm.After the aging treatment, the repair area begins to grow and merge .The results of SEM analysis show that :There is no γ＇appear at the as-deposited , and the cubic MC type carbide is formed at the interdendritic, and the M23C6 type carbide at the dendrite arm ; After the aging treatment, γ＇phase precipitated at the repair area: γ＇phase with an average size of 37nm was found in the repair area, and the carbide precipitates in the grain boundary with the character of discontinued when the temperature of the stabilization step is 820℃; With the increase of the stabilization temperature, the size of the γ＇ and carbide increases ;When the temperature is 840℃, the average size of the γ＇is about 76nm, and the carbide is precipitated in the form of necklace ;Adding the temperature of the stabilization step to 860℃ , the average size of the γ＇does not increase obviously, and part of the γ＇ of is obviously coarsening and the size reach 150nm, meanwhile the carbides at the grain boundaries begin to form the closed. The results of mechanical property show that :the tensile strength of the sample increases obviously after aging treatment,and with the increase of the temperature, the tensile strength increases first and then decreases, and the elongation decreases continuously.