Effect of Ultrasonic Rolling Process on Surface Quality of Laser Cladding Layer of Die Steel

Ultrasonic rolling technology is an economic and efficient means, and a new surface finishing and strengthening technique which can effectively improve the quality of metal surface. H13 die steel was coated with iron base alloy by laser cladding technology,and the effect of ultrasonic rolling process parameters on the surface microstructure and quality of laser cladding layer were investigated. SEM, EDS and XRD were carried out to study the microstructure of the rolled surface, and surface roughness instrument,white light interferometer, hardness tester and residual stress tester were performed to measure their roughness, hardness and residual stress. The results show that the microstructure of the cladding layer was refined obviously after ultrasonic rolling. The grain size increases gradually with the increase of the depth from the surface, and the direction of microstructure deformation is the same as that of ultrasonic rolling. The surface roughness after rolling has a linear positive correlation with the initial surface roughness. With increasing reduction, static pressure, rolling rate and rolling times, the surface roughness decreases first and then increases, and the surface hardness increases first and then decreases. The surface residual stress increases first and then decreases with the increase of reduction, static pressure and rolling times. The metal surface has a good finishing and strengthening effect at the value of reduction of 0.10 mm, static pressure of 0.45-0.65 MPa, rolling rate of 2 100 mm/min and rolling times of 3.