Theoretical Analysis of Laser Transformation Hardening Process of Hypoeutectoid Steel based on Kinetics

Coupling effects between the temperature field and structural changes are considered in the analysis of the laser transformation hardening process. The volume fractions of the structural constituents, the latent heat during the phase transformation and structure dependence of the thermophysical properties are introduced during the iterational calculations of the steady-state temperature distribution and the structural changes. The carbon content of a steel, the mean value of the grain size of the prior austenite, and the size and the interlamellar spacing of the pearlite colony are input for the initial parameters. Finite-element calculations are carried out to obtain the temperature distribution and the structural changes in the process, and the microhardness distribution in the hardened layer. An example of the numerical computations is shown for a 0.45 %C carbon steel. The calculated results are compared with those of the experiments on the laser transformation hardening and are found to be in good agreement.