Laser cladding repair process for gear

The invention relates to a laser cladding repair process for gear, which comprises the following steps: (A) treating the surface of the valve seat and performing failure analysis on the valve seat; (B) integrally preheating the gear at 80-120 DEG C and locally preheating the portion to be repaired of the gear at 80-220 DEG C at the same time; (C) optimizing technological parameter according to the failure analysis result of the gear, and performing laser cladding on the valve seat layer by layer, the thickness of each cladding layer is less than or equal to 0.4 mm, the edge of the later cladding layer extends out of the edge of the former cladding layer by 4 mm to 6 mm, the powdered alloy adopted is prepared from the following components in percentage by weight: less than or equal to 0.5% of carbon, 38-52% of chromium, 1.5-2.5% of boron, 0.5-1.5% of silicon and the balance of ferrum; and (D) performing detection. The surface of the gear is subjected to laser cladding through the laser repair process for gear, so that the size of the valve seat is recovered to operating requirement, and the hardness and abrasive resistance of the valve seat repaired exceed its original performance.