Effects of laser shock processing without coating on mechanical properties of K24 nickel based alloy

Laser shock processing is a novel surface treatment technology to increase the fatigue strength of materials. Based on the characteristic of K24 nickelbased alloy simulation blades, the laser shock processing without coating (LSPwC) was carried out. Whilst the change discipline of micro-hardness and residual stress on the cross-section of K24 nickel-based alloy after different parameters of LSPwC were examined by micro-hardness tester and residual stress tester. In addition, the high cycle fatigue tests were conducted to verify the reinforcement effect. The experimental results show that particular compressive residual stress on the surface was induced by LSPwC, the largest residual stress value was -428, -595, -675 MPa with 110, 150, 160 m depth affected layer under 1, 3, 5 impacts respectively. The surface micro-hardness was increased by 29.2% with 60 m depth under one impact. The fatigue strength of simulation blades was improved from 282 MPa to 327 MPa, improved by about 16% after unequal stress impact.