Study on Microstructure and Properties of Repair Layer of 40Cr Steel by Pulse Cold Welding

In order to further improve the strength, hardness and wear resistance of the welded repair layer of steels for shafts, the surface of 40 Cr steel was repaired by high-energy pulse cold welding technology. The microstructure and hardness of the base metal and the cold welding repair layer were analyzed and compared by OM, SEM and microhardness tester. The tensile property and wear resistance of the repaired layer were tested. The results show that the microstructure of the cold welding repair layer is mainly lath-like martensite with high hardness, the tensile parts are fractured at the base metal position,and the average tensile strength is 803.8 MPa. Under dry friction conditions, the wear resistance of the repaired layer is good,the friction coefficient and wear amount are close to those of the 40 Cr steel, and the wear mechanism is mainly abrasive wear.