Thermal analysis of a laser pulse for discrete spot surface transformationhardening

Conventional laser transformation hardening is achieved by scanning a laser beam over a surface to raise the temperature above the austenitizing tempe rature and allowing self quenching to form martensite. A new approach, deve loped at the National Research Council of Canada's Integrated Manufacturing Technologies Institute, uses discrete pulses to create a series of hardene d "spots.'' Unfortunately, existing transformation hardening models do not apply to this case due to the traditional assumption of a scanning velocity . For this reason, new predictive tools must be developed. An analytical so lution to the axisymmetric heat conduction under a Gaussian energy distribu tion is presented which can be used to calculate the temperature distributi on from a short laser pulse. The method is also used to calculate the size of a transformation hardened spot under the incident energy of a stationary laser. [S0021-8979(99)07104-2].