Effect of the ball burnishing on the surface quality and mechanical properties of a TRIP steel sheet

Ball burnishing is a finishing technique involving plastic deformation on the workpiece surface. In this paper, the influence of the ball burnishing operation on the average roughness, tensile properties, anisotropy and work hardening of a TRIP steel was analyzed. An experimental study of the effect of the ball burnishing process on uniaxial tensile specimens was conducted using the Response Surface Methodology (RSM) based on a 3 2 Factorial Design (FD). The effects of burnishing force ( B F ) and the number of tool passes ( N P ) on the average roughness ( R a ), the yield stress ( σ Y ) and the percentage of elongation to fracture ( % E l ) were evaluated. The quadratic regression models were obtained to predict R a and σ Y with determination coefficients ( R 2 ) of 0.85 and 0.99, respectively. The results indicated that the ball burnishing process produces a maximum reduction of R a of 81.7 % (from 1.250 to 0.229μm). Also, it was observed that the ductility of the material increased in a 25 % and the yield stress and work hardening can be substantially modified. Finally, it was found that by using the ball burnishing process, the planar anisotropy of the sheet can be reduced.