Laser repairing surface crack of Ni-based superalloy components

Surface crack of components of the cast nickel base superalloy was repaired with twin laser beams under proper technological conditions. One laser beam was used to melt the substrate material of crack, and the other to fill in powder material to the crack region. The experimental results show that the surface crack with the width of 0.1 ～ 0.3?mm could be repaired under the laser power of 3?kW and the scanning speed of 6 ～ 8?mm/s. The repaired deepness of crack region is below 6.5?mm. The microstructure of repaired region is the cellular crystal, columnar crystal dendrite crystal from the transition region to the top filled layer. The phases in repaired region mainly consisted of supersaturated α Co with plenty of Ni, some Cr and Al, Cr 23 C 6, Co 2B, Co Ni Mo, Ni 4B 3, TiSi and VSi. The hardness of filled layer in repaired region ranged from HV 0.2 450 to HV 0.2 500, and the hardness decreases gradually from the filled layer to joined zone.