Controlling thermal deformation using a heat sink in laser transformation hardening of steel sheets

Experiments were conducted using a 3 kW diode laser on 2 mm thick boron steel and DP 590 dual phase steel specimens, and four types of heat sink were considered: stainless steel 316, steel, and copper, and no heat sink. Deflection angles were measured and microstructure distributions were analyzed. When a heat sink is used, thermal deformation can be significantly reduced to the point where the direction of deflection can be reversed, and a zero deflection regime exists between the two different deflection regimes. Two different thermal deformation mechanisms are involved, plastic deformation and deformation due to martensitic phase transformation, and between them a transition regime exists. Thermal deformation in not only the laser transformation hardening process but also general laser-based sheet metal manufacturing processes can be effectively controlled.