Influence of the Carbon Content on the Surface Integrity of Deep Rolled Steels

Abstract

Surface integrity refers to a set of characteristics of the surface and subsurface layers that have great influence on the functional performance of mechanical components under conditions of wear, corrosion, and fatigue and is determined by the manufacturing processes employed. Thus, surface treatments are used to generate a surface integrity suited to the desired function. Deep rolling is one of the surface treatments that involve cold working of the surface and subsurface layers. This work addresses the influence of selected deep rolling parameters (pressure, speed, feed, and number of passes) on the surface integrity (roughness, surface and subsurface microhardness, and microstructure) of AISI 1020, AISI 1065, and AISI 1080 carbon steels. Deep rolling significantly improved the surface finish; however, the excessive increase in pressure, associated with the reduction of the carbon content, and in feed, associated with the increase in the carbon content, increased the roughness. An increase in the number of passes, on the other hand, improved the surface finish in some cases. Under all conditions tested, deep rolling increased the microhardness of the subsurface layer and affected depth. Finally, the microstructure analysis showed that the increase in the carbon content promoted a reduction in grain deformation caused by deep rolling. Grain deformation was found to increase in AISI 1020 and AISI 1065 steels with increasing pressure and to reduce with the elevation of rolling speed and feed. The number of passes, on the other hand, affected only the subsurface layer of AISI 1020 steel.