Modeling and Simulation of Phase Transformation during Grinding

Abstract

The grinding process is one of the most important finishing processes in production industry. During the grinding process the workpiece is subjected to mechanical and thermal loads. They can induce thermal damages in terms of phase transformation due to critical temperature history. A holistic model helps to describe and predict the influence of these loads on the residual stresses in the surface layer. In this paper, a very promising approach using the Finite Element Method (FEM) to simulate the surface grinding process in terms of thermal and mechanical loads during grinding of hardened and tempered steels with vitrified bonded CBN grinding wheels is introduced. The investigations were conducted for deep, pendulum and speed stroke grinding. The change of workpiece material properties was modelled as a function of temperature and phase history. The results lead to the necessary time depending temperature distribution within the surface layer. Hence, the phase transformation can be calculated. The FEM software "Sysweld" was used to analyze the phase transformation kinetics. Hence, the size of the rehardened zone after grinding can be predicted. The evaluation of the FEM model with micrographs of ground workpiece specimens showed a strong correlation for different grinding parameters. Based on the understanding of mechanical and thermal loads as well as phase transformation kinetics in the surface layers the resulting residual stresses can be determined.

A New Approach for the Prediction of Surface and Subsurface Properties after Grinding

“…High values of ∆t together with relatively low values of T max lead to compressive residual stresses below -200 MPa at the workpiece surface (noted as the compressive residual stress area). This implies a low thermal impact combined with a high dominating mechanical load during grinding leading to the resulting residual stress state [14]. In contrast, a low contact time in combination with high maximum contact zone temperatures lead to a reduction of compressive residual stresses up to zero.…”

Application of axiomatic design principles to identify more sustainable strategies for grinding

“…For example, Mahdi and Zhang [30] examined how the temperature gradients, mechanical stresses, and phase transformations affect residual stresses in grinding. Duscha et al [31] used a FEM approach to simulate phase transformation during grinding and add residual stresses that result from these phase transformations. Brinksmeier et al [32] investigated the phase transformation of steel during grind-hardening, which involves multiple effects on surface integrity.…”

Material phase transformation at high heating rate during grinding

“…Some numerical methods have been developed to analyze the thermo-metallurgical or thermo-mechanical effects during grind-hardening, such as transient temperature distribution, micro-structural transformation, part distortions and surface integrity (Brinksmeier et al, 2003;Foeckerer et al, 2012Foeckerer et al, , 2013Kolkwitz et al, 2011aKolkwitz et al, , 2011bMahdi and Zhang, 2000;Nguyen and Zhang, 2011;Zaeh et al, 2009). Duscha et al (2011) modeled and simulated the change of material properties as a function of temperature and phase history during grinding. Compared with other material removal processes, grinding operation requires more energy and thus higher specific energy to remove the same material volume and will subject the workpiece into complex thermal strain and stress.…”