A Grinding-Burnishing Approach to Enhancing Surface Integrity, Tribological, and Corrosion Behavior of Laser-Cladded AISI 431 Alloys

Abstract

This paper presents the influence of the grinding-burnishing on surface integrity and corrosion performance of the laser-cladded AISI 431 alloys. As-cladded specimens were first ground followed by ball burnishing. To evaluate surface alteration and performance enhancement, six major properties were measured and analyzed in terms of surface roughness, porosity, microhardness, wear, and impact and corrosion resistance. Results showed that grinding-burnishing significantly improved the surface finish by lowering Ra and Rz by up to 29% and 41%, respectively, compared with grinding. Surface porosity was found to decrease by 18%. Maximum surface microhardness increased by 32% when grinding-burnishing, with a modified depth of up to 250 µm, while wear resistance in terms of volume loss increased by up to 38%. Because of hardness improvement, the grinding-burnishing increased the impact resistance by lowering the maximum indent depth by 29%. The corrosion resistance improved by increasing positive corrosion potential from −0.31 V (grinding) to −0.21 V (grinding-burnishing) and lowering corrosion current density from 1.18 × 10−3 A.cm−2 (for grinding) to 2.1 × 10−5 A.cm−2 (grinding-burnishing). Burnishing further induced grain modification in terms of grain deformation and flattening within microstructure, but no grain refinement was observed. XRD results however showed lattice deformation indicating potential compressive residual stress generated by burnishing. Overall, it is imperative to say that the combined grinding-burnishing can be a viable surface modification technique to extend functional service life of the laser-cladded components.