The scope of this thesis is to investigate the effect of main parameters on laser surface hardening of X12CrNiMoV12 stainless steel. LSH was carried out using high power co 2 laser which delivers a maximum output power of 4 KW in continuous mode at Gaussian form of intensity profile. Experiment has been carried out using defocus technology. A numerical simulation of laser hardening process has been developed using finite element method to solve heat transfer equation inside the treated material. Temperature measured with k type thermocouple. By use of sand blast and graphite coating the absorptive of laser beam has been increased. From the results of the experiments, it has been shown that absorptivity can increase from 6 to 85% by combination of sand blast and paint coating. The maximum hardness of surface is approximately 570HV. Hardening depth is dependent with power, velocity and beam radius. Hardening width is dependent with velocity and beam radius. The main result of this research is a diagram (laser hardening map) can predict the hardening characteristic of X12CrNiMoV12 for wide range of laser parameters. Key Words Laser hardening, X12CrNiMoV12, CO 2 laser, martensite, Finite element, Simulation, martensitic stainless steel, ANSYS
