Thermal gradient and its contribution to size effect of specific cutting energy
The size effect of specific cutting energy is one of the most fundamental and challenging problems in metal cutting. The size effect phenomenon has been attributed to the material strengthening effect due to strain, strain rate, and strain gradient. However, the contribution of the material strengthening caused by temperature effect in the primary shear zone is rarely studied. Here, orthogonal cutting experiments under different initial temperature were conducted. It shows the significant dependence of the size effect phenomenon on the temperature effect. The finite element methods were further conducted to reveal the underlying reason of the size effect. It is found that there exists high-temperature gradient in the primary shear zone along the shear direction, which causes the average temperature in the primary shear zone to drop with decreased uncut chip thickness, giving rise to the size effect phenomenon. Furthermore, a new approach is developed to predict the highest temperature in the primary shear zone by numerical fitting.
KeywordsSize effect Thermal gradient Specific cutting energy Material strengthening
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Financial support is from NSFC (Grants no. 11402278).
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