Selective modification of dual phase steel DP 1000 by laser action using diffractive optical element

Experimental studies of shaping a CO2 laser beam with a reflective diffractive optical element have been performed. To increase the aperture of the initial beam, we used a collimator containing a system of two plane-convex spherical ZnSe lenses. For the focal line formed with the diffractive optical element in combination with the collimator, in addition to a 1.3-fold increase in the length, a decrease in the maximum beam power density was found to occur in the laser spot. It was demonstrated that under the laser action it is possible to generate in a two-phase steel sample regions of full hardening, selective hardening, and annealing, alongside the initial structure. The formation of such structures is due to the distribution pattern of temperature fields and a difference in the cooling rate across the volume of the heat affected zone.