In-process residual stresses regulation during grinding through induction heating with magnetic flux concentrator

Abstract

Super-alloy Inconel 718, which has advantages of high temperature strength and corrosion resistance, is widely applied as the high temperature components of the turbine engines in the energy and aerospace manufacturing industry. Grinding is generally used as the final material removal process to acquire good dimensional accuracy and surface quality. However, the large residual tensile stress is often obtained on the ground workpiece surface, which is harmful and detrimental to the fatigue strength and service life of the component. In this paper, a novel approach of regulating the residual stress during grinding assisted by induction heating is proposed and validated by simulation and experiments. The principle of this method is to regulate the grinding temperature distribution profile by implanting a sub-surface heat source with well-controlled induction heating technology. Then the temperature profile along the depth during grinding becomes more uniform thus diminishes the formation of tensile stress. The function mechanism of the induction heating with magnetic flux concentrator (MFC) is studied and the finite element model is carried out to study the feasibility of the process. In addition, the experimental platform of this novel induction heating assistant grinding system is established, and several sets of experimental studies are carried on. The results show that, compared with ordinary grinding, the surface residual stress under the novel technology has been improved a lot, which further verifies the proposed regulation mechanism of residual stress in this paper is feasible and available. At the same time, the influence of the process parameters on the final residual stress distribution is studied. Combined with the results of the simulation and experiment analysis, the ultimate realization of active control under the novel technology of residual stress is achieved, which can provide the basis for the process design and optimization for in-depth research.