Phase Transformation Prediction Considering Crystallographic Orientation in Microgrinding Multiphase Material

2020 ◽  
Vol 142 (10) ◽  
Author(s):  
Man Zhao ◽  
Xia Ji ◽  
Yixuan Feng ◽  
Steven Y. Liang
Keyword(s):  
Phase Transformation ◽  
Crystallographic Orientation ◽  
Factor Model ◽  
Taylor Factor ◽  
Depth Of Cut ◽  
Kinetics Parameters ◽  
Order Of Magnitude ◽  
Solid State Phase Transformation ◽  
Temperature Rate ◽  
Previous Prediction

Abstract This investigation proposes a physics-based model to predict the solid-state phase transformation of maraging steel subjected to microgrinding. In microgrinding, the effect of crystallography is significant on the grinding phase transformation in light of the fact that the depth of cut is on the same order of magnitude as the grain size. This paper proposes a predictive model of phase transformation considering crystallographic orientation (CO) with respect to the grinding direction based on the Taylor factor model. In addition, the flow stress model is modified by adding a CO sensitive term and incorporating the mechanical-thermal loadings. Furthermore, the temperature, temperature rate, strain rate, and Taylor factor are also combined in the model of phase transition. The kinetics parameters of the models are obtained by a regression analysis against experimental data. Finally, the modified models are validated with experiments data and compared with the previous prediction.

Influence of AA7075 crystallographic orientation on micro-grinding force

2018 ◽  
Vol 233 (8) ◽  
pp. 1831-1843 ◽  
Author(s):  
Man Zhao ◽  
Xia Ji ◽  
Steven Y Liang
Keyword(s):  
Flow Stress ◽  
Crystallographic Orientation ◽  
Factor Model ◽  
Grinding Force ◽  
Taylor Factor ◽  
Depth Of Cut ◽  
Grinding Wheel ◽  
Force Model ◽  
Workpiece Material ◽  
Flow Stress Model

In micro-grinding, the depth of cut is smaller than the grain size of workpiece material. Since the micro-grinding wheel cuts through the grain boundaries, the crystallographic effects become more significant in the micro-grinding than that in macro-machining. To quantify the effect of crystallographic orientation on the flow stress of polycrystalline material, the Taylor factor model is developed by examining the number and type of the activated slip systems. Then, the shear force model is developed based on the flow stress model considering the effect of crystallographic orientation. Moreover, the plowing force is predicted based on the Vickers hardness of workpiece material and the plowing friction coefficient. A comprehensive model is then proposed to predict micro-grinding force by consolidating the mechanical, thermal, crystallographic, and size effect. Micro-grinding experiments adopting Taguchi’s method were conducted to verify the model, and the results indicated that the predictions agree well with the experimental data. Besides, single-factorial experiments were conducted with the only variable being Taylor factor and the results suggest that the Taylor factor model is capable of capturing the effect of crystallographic orientation on grinding force.

scholarly journals Micro-grinding temperature prediction considering the effects of crystallographic orientation

2019 ◽  
Vol 6 ◽  
pp. 22
Author(s):  
Man Zhao ◽  
Xia Ji ◽  
Steven Y. Liang
Keyword(s):  
Crystallographic Orientation ◽  
Thermal Loading ◽  
Factor Model ◽  
Orientation Distribution ◽  
Taylor Factor ◽  
Energy Partition ◽  
Grinding Forces ◽  
Material Microstructure ◽  
Temperature Prediction ◽  
Experimental Values

Tensile stress and thermal damage resulting from thermal loading will reduce the anti-fraying and anti-fatigue of workpieces, which is undesirable for micro-grinding, so it is imperative to control the rise of temperature. This investigation aims to propose a physical-based model to predict the temperature with the process parameters, wheel properties and material microstructure taken into account. In the calculation of heat generated in the micro-grinding zone, the triangular heat-flux distribution is adopted. The reported energy partition model is also utilized to calculate the heat converted into the workpiece. In addition, the Taylor factor model is used to estimate the effects of crystallographic orientation (CO) and its orientation distribution function (ODF) on the workpiece temperature by affecting the flow stress and grinding forces in micro-grinding. Finally, the physical model is verified by performing micro-grinding experiments using the orthogonal method. The result proves that the prediction matches well with the experimental values. Besides, the single-factorial experiments are conducted with the result showing that the model with the consideration of the variation of Taylor factor improves the accuracy of the temperature prediction.

scholarly journals Forces prediction in micro-grinding single-crystal copper considering the crystallographic orientation

2018 ◽  
Vol 5 ◽  
pp. 15
Author(s):  
Man Zhao ◽  
Xia Ji ◽  
Beizhi Li ◽  
Steven Y. Liang
Keyword(s):  
Flow Stress ◽  
Single Crystal ◽  
Crystallographic Orientation ◽  
Factor Model ◽  
Taylor Factor ◽  
Force Model ◽  
Stress Model ◽  
Single Crystal Copper ◽  
Accuracy Of Prediction ◽  
Flow Stress Model

In the micro-grinding of single-crystal copper, the effect of crystallography becomes significant as the wheel works intra-crystalline. To quantify the effect of crystallographic orientation (CO) related to the cutting direction on the micro-grinding process, this article presents a Taylor factor model by examining the number and style of activated slip systems. Then, the flow stress model of monocrystalline material is developed considering the variation of the Taylor factor. Furthermore, the models of chip formation and rubbing forces are derived from the flow stress model, while the plowing force is predicted by the Vickers hardness. Then, the overall grinding force model of the whole wheel is developed by incorporating the process parameters and the wheel properties. Finally, micro-grinding experiments are conducted to verify the model, using only the Taylor factor as the variable. The proposed analysis is also compared with the previously reported model, which considers the Taylor factor as a constant of 3.06. The comparison between the two predictions and experimental data shows that the consideration of Taylor factor variability improves the accuracy of prediction.

Effect of crystallographic orientation on the hardness of polycrystalline materials AA7075

2018 ◽  
Vol 233 (9) ◽  
pp. 3182-3192
Author(s):  
Man Zhao ◽  
Xia Ji ◽  
Beizhi Li ◽  
Steven Y Liang
Keyword(s):  
Experimental Data ◽  
Flow Stress ◽  
Vickers Hardness ◽  
Crystallographic Orientation ◽  
Factor Model ◽  
Taylor Factor ◽  
Polycrystalline Materials ◽  
Compression Tests ◽  
Micro Hardness ◽  
Model Compression

As one of the most important properties of materials, micro-hardness is influenced by material microstructure significantly. The reported data show that the micro-hardness of materials varies with the variation of crystallographic orientation. This paper presents an analytical model to quantify the effect of crystallographic orientation on micro-hardness by analyzing the mechanical behavior in the test of Vickers hardness. The plastic deformation occurs under the micro-indentation with the flow stress affected significantly by crystallographic orientation of material. This paper develops a Taylor factor model to quantify the effect of crystallographic orientation on the flow stress of polycrystalline materials, by examining the number and the style of activated slip systems. Considering the linear relationship between the flow stress and Vickers hardness, the effect of crystallographic orientation on the Vickers hardness is established. To verify the Taylor factor model, compression tests and Vickers hardness tests were conducted. The result shows that the predictions coincided with the experimental data, which suggests that the model considering the variation of crystallographic orientation is accurate and the Taylor factor model is reasonable. To analyze the sensitivity of flow stress and Vickers hardness to CO, this paper also predicted flow stress and hardness using models without considering the variability of Taylor factor and the athernal stress. The three predictions were compared with the experimental data, and the results proved that the model considering the variability Taylor factor improves flow stress and accuracy of hardness models.

scholarly journals Solid state phase transformation kinetics in Zr-base alloys

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
A. R. Massih ◽  
Lars O. Jernkvist
Keyword(s):  
Phase Transformation ◽  
Solid State ◽  
Zirconium Alloys ◽  
Excess Oxygen ◽  
Transformation Kinetics ◽  
Fuel Cladding ◽  
Reactor Accident ◽  
Phase Transformation Kinetics ◽  
Solid State Phase Transformation ◽  
Water Reactors

AbstractWe present a kinetic model for solid state phase transformation ($$\alpha \rightleftharpoons \beta$$ α ⇌ β ) of common zirconium alloys used as fuel cladding material in light water reactors. The model computes the relative amounts of $$\beta$$ β or $$\alpha$$ α phase fraction as a function of time or temperature in the alloys. The model accounts for the influence of excess oxygen (due to oxidation) and hydrogen concentration (due to hydrogen pickup) on phase transformation kinetics. Two variants of the model denoted by A and B are presented. Model A is suitable for simulation of laboratory experiments in which the heating/cooling rate is constant and is prescribed. Model B is more generic. We compare the results of our model computations, for both A and B variants, with accessible experimental data reported in the literature covering heating/cooling rates of up to 100 K/s. The results of our comparison are satisfactory, especially for model A. Our model B is intended for implementation in fuel rod behavior computer programs, applicable to a reactor accident situation, in which the Zr-based fuel cladding may go through $$\alpha \rightleftharpoons \beta$$ α ⇌ β phase transformation.

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