Finite Element Simulation and Experimental Investigation of Nanostructuring Burnishing AISI 52100 Steel Using an Inclined Flat Cylindrical Tool

Abstract

This article is devoted to the development of a sliding burnishing scheme using a flat cylindrical indenter. The previously established patterns of nanostructured state formation in the AISI 52100 steel subsurface layer showed a need to create a special tool with a variable tilt angle of the indenter and with force regulation. A new tool with a cubic boron nitride indenter opens wide possibilities for nanostructuring burnishing of hardened bearing steel. Firstly, a flat cylindrical indenter has high durability due to repeated rotation around its axis. Secondly, the change of the tilt angle to the treated surface allows controlling the contact compression pressure and plastic shear deformation, which determines the formation of a nanostructured state of the material by the method of severe plastic deformation (SPD). The purpose of the work is to determine the optimal parameters of the process and tool in order to form a nanostructure and significantly increase surface layer microhardness. The goal was achieved by the methods of finite element modeling (FEM) and experimental studies of burnishing when the indenter tilt angle changes from 0.5° to 2.5° under dry processing conditions. Numerical simulation of the process made it possible to establish optimal values of the indenter tilt angle of 2° and the burnishing force 250 N according to the criteria of maximum contact pressure and cumulative deformation. The experimental studies of cumulative deformations and the coefficient of friction by the method of burnishing a split disc and dynamometry of the process confirmed the FEM results. The transmission microscopy, durometry, and 3D surface profilometry showed the sensitivity of nanocrystallite sizes, microhardness, and roughness to an indenter tilt angle and confirmed the optimality of the established tilt angle value.