Analysis of the Surface Residual Stress in Grinding Aermet100

Abstract

Grinding induces residual stresses, which can play an important role on the fatigue of the component. In general, residual stresses in a ground surface are primarily generated due to three effects: thermal expansion and contraction during grinding, plastic deformation caused by the abrasive grains of the wheel and phase transformations due to high grinding temperature. It was found that thermal expansion and plastic deformation in the grinding process were the major causes of residual stresses. In this paper, an analysis model for the calculation of residual stresses induced by a surface grinding process on an ultrahigh-strength steel (Aermet100) workpiece is presented. Firstly, the stress distribution induces by thermal expansion was obtained base on the transient heat conduction equation and the thermal properties of Aermet100. All the calculations were based on the moving heat source solution which was modeled as a uniformly distributed, 2D heat source moving across the surface of a half-space, found in Carslaw and Jaeger. The results show that the near surface residual stress is predominantly tensile and that the magnitude of this stress increases with increasing heat flux values. Secondly, the plastic deformation caused by the abrasive grains of the wheel was simulated base on the grain-workpiece interaction. The chip formation process and the material removal mechanisms can be examined using the micro-scale approach. The results show that the residual stress induced by the grinding force itself is generally compressive which is smaller than the residual tensile stress induced by thermal stress. Therefore, the residual stress brought about by grinding operation is generally a tensile stress. This paper offers an insight into the mechanism understanding of thermal and mechanical residual stresses induced by surface grinding. Key words: grinding, residual stress, grain

Abrasive machining of advanced aerospace alloys and composites

“…Subsequent trials also highlighted that compressive residual stresses up to $1000 MPa extending to a depth of $30 mm was obtained when surface grinding AerMet 100 using CBN wheels at a workpiece feed (v w ), wheel speed (v s ) and depth of cut (a p ) of 18 m/min, 14 m/s and 10 mm respectively [246]. In contrast, the majority of trials involving white Al 2 O 3 wheels exhibited tensile residual stresses similar to that reported by Xu et al [242]. The feasibility for creep feed grinding of AISI 420 stainless steel using a vertical high-speed machining centre was demonstrated by Dewes et al [51].…”

“…Xu et al [242] studied the abrasive machining of AerMet 100 using white Al 2 O 3 vitrified grinding wheels. Tensile residual stresses were detected in the top surface layer, which crossed over to the compressive regime when moving deeper into the subsurface zones.…”

Review on grinding-induced residual stresses in metallic materials

“…Grinding-induced residual stresses in a component are primarily due to three causes: (1) localized thermal expansion or contraction of the component material during grinding, (2) plastic deformation due to grinding wheel abrasion, and (3) localized phase transformation-induced volume change [5,28,29]. Generally, thermally and (a) workblank before grinding (b) grinding of blade (c) grinding of rabbet Fig.…”

“…Surely, it is also very important to evaluate which effect is predominant when the coupled mechanical-thermal effects are taken into consideration. Xu and Zhang [29] predicted the residual stresses generated in grinding of the ultra-highstrength steel Aermet100. Both the mechanical load induced by the wheel-workpiece interaction and the moving thermal source model with 2D uniform distribution have been applied.…”

“…However, the residual stresses induced by the mechanical load are generally compressive, the amplitude of which is smaller than the tensile residual stresses induced by the thermal load. As a result, the total residual stresses brought about by the grinding operations are generally tensile [29].…”