Temperature Field of Repetitive Laser Pulse Irradiation and Its Effect on Laser Surface Hardening

Analytical expressions for the temperature rise in a semi-infinite workpiece due to the heating with CW and repetitive laser pulse irradiation have been derived. It has been shown that the soaking time at a temperature above the phase transformation temperature, on which the homogeneity of microstructure and the depth of hardening depend, can be increased by heating with repetitive laser pulses. Experimental results of surface hardening of high-carbon steel with repetitive laser pulses showed higher depth of hardening and better microstructure homogeneity compared to those with continuous wave laser.