Process map approach to laser transformation hardening of carbon steels

Abstract

In this study, we present a novel approach for studying laser transformation hardening of carbon steels based on process maps [1]. Due to the uniform beam profile, this approach is especially suited for diode lasers. Using the melting temperature and A3 temperature of the steel, the heat treatable region is defined on the intensity-interaction time diagram, on which effective carbon diffusion time, effective cooling time, and hardening depth are computed and displayed, all of which are primary parameters in the laser transformation hardening of carbon steels. To validate this approach, we have conducted a systematic experiment on AISI 1020 and 1035 steel specimens using a 3 kW diode laser and measured surface hardness and hardening depth. The obtained experimental measurements are in good agreement with the theoretical predictions.