Simulation and experimental study on residual stress of ultra-high strength steel under powerful rolling

This work aims to study the effects of different powerful rolling process parameters on surface residual stress distribution of ultra-high strength steel. In order to strengthen the surface of ultra-high strength steel, a powerful rolling strengthening process is proposed. Carbide rolling tools are used to apply rolling pressure greater than 2500 N to the sample. A single factor test of powerful rolling strengthening is carried out. Based on SEM and EBSD tests, the effects of powerful rolling strengthening on surface microstructure of ultra-high strength steel is analyzed. Furthermore, the residual stress distribution on the surface and surface layer of the ultra-high strength steel under different rolling parameters are analyzed. Finally, through ABAQUS finite element simulation, a prediction model for the residual stress field of ultra-high strength steel with powerful rolling strengthening is established. The simulated and experimental values of residual stresses are compared. As a result, powerful rolling strengthening refines the surface martensite grains of the ultra-high strength steel, reducing the average grain size from 0.813 μm to 0.474 μm, and the martensite grains deformation slip along the rolling direction. Powerful rolling strengthening can increase the residual compressive stress value of the ultra-high strength steel surface from –276 MPa to a maximum of –942 MPa, and the depth of the residual compressive stress from 0.2 mm to a maximum of 0.9 mm. The distribution of the residual stress in the radial direction of powerful rolling strengthening test and the simulation are consistent. The error between the simulation value and the experimental value of the rolling surface compressive stress is less than 27%. Test analysis shows that powerful rolling strengthening can effectively refine the surface grain of the ultra-high strength steel 45CrNiMoVA and improve the residual stress distribution. The residual compressive stress value increases with the increase of the rolling depth and the number of rolling times, and decreases with the increase of the feed rate and the workpiece speed. The powerful rolling simulation accurately predict the distribution of residual stress in the surface layer after rolling. It provides technical guidance for solving the surface strengthening problems of a class of difficult-to-cut materials such as ultra-high strength steel 45CrNiMoVA.