Superposition of laser and ultrasonic actions for heat treatment of steel surface

We examine experimentally the processes of structure formation and formation of the residual stress during the laser and ultrasonic heat treatment of steel surface, taking into account the theoretical premises of ultrasonic sound influence on the phase conversions and diffusion behaviour in the high rate of laser heating and cooling conditions. We show that under the laser-ultrasonic treatment the forming areas of hardening are harder and deeper. The plastic straining of surface by the ultrasonic action has an observable effect on the completeness of the austenitization process and allows controlling the stress state of surface in the area of laser treatment efficiently. The conditions of superposition of laser and ultrasonic actions are optimized to the unital scheme of surface heat treatment. The possibility of using ultrasonic sound for local heating of the laser heat hardening area and focused changing of its structural stress state is demonstrated.