Abstract: Cold-welding technology is a new type of metal surface repair technique with advantages of precision, economy and convenience, and has been widely used in engine remanufacturing and other fields. The surface defects of HT250 material used in engine cylinder are repaired by cold-welding technology, then the metallographic microscope, scanning electron microscope, microscopic hardness meter and tensile testing machine are used to analyze microstructure, hardness and bonding strength of repaired region. Meanwhile, the impacts on repaired layer of different process parameters are revealed. Analysis results show that base and repaired layer combine well without pores and cracks, and element diffusion exists in the fusion interface, which illustrates that the relationship between repaired layer and base is metallurgical bonding. The hardness of repaired layer is lower than that of base, which is beneficial to subsequent processing. The width of heat affected zone (HAZ) is relatively narrow. Cold-welding repair technique can improve tensile strength of repaired object. After analyses, the following trends can be obtained that width and hardness of HAZ increase with the increase in time and energy parameters of cold-welding, while tensile strength firstly decreases and then increases.

Key words: Cold-welding, Engine, Parameters, Remanufacturing