Comparison of Effects of Laser, Ultrasonic, and Combined Laser-Ultrasonic Hardening Treatments on Surface Properties of AISI 1045 Steel Parts

Abstract

An ultrasonic impact treatment (UIT) in combination with laser heat treatment (LHT) is proposed to improve surface roughness and enhance the subsurface grain refinement and residual stress of hypoeutectoid steel. The LHT treatment was conducted using a fiber laser with 2D scanning optics. The UIT treatment was performed using a multi-pin ultrasonic tool. The surface texture, roughness parameters, and surface hardness of the UIT, LHT, UIT+LHT, and LHT+UIT hardened samples were studied and compared. The surface roughness and hardness were under special attention as possible key factors to additional optimization of the UTI duration. The results indicated that the combined UIT +LHT technique could be applied to get both significant surface hardness and hardening depth in AISI 1045 medium carbon steel. The combined LHT-UIT hardened specimens exhibited the lowest surface roughness and highest surface hardness, which was attributed to the surface attributed to the surface relief and ultrafine-grained martensitic structure in the subsurface formation.