Enhanced Surface Integrity From Cryogenic Machining of AZ31B Mg Alloy: A Physics-Based Analysis With Microstructure Prediction
Enhanced Surface Integrity From Cryogenic Machining of AZ31B Mg Alloy: A Physics-Based Analysis With Microstructure Prediction
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DOI：
10.1115/1.4034279
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发表时间：
2017-06
影响因子：
4
通讯作者：
N. Shen;Hongtao Ding;Z. Pu;I. Jawahir;T. Jia
中科院分区：
文献类型：
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作者：
N. Shen;Hongtao Ding;Z. Pu;I. Jawahir;T. Jia
镁（Mg）合金的使用一直在不断增加， 在运输/航空航天工业中的广泛应用， 轻量化和其他领域，如可生物降解的医疗植入物。这是 最近表明，机械加工可以用来改善功能性能 镁基产品/部件的耐腐蚀性等，通过 工程表面完整性。本文研究了AZ31B镁合金在高温下的力学行为， 首先讨论了低温加工。表面完整性可以是 通过引入超细晶粒（UFG）层， 低温加工过程中的严重塑性变形（SPD）效应。的 分析了组织演变和塑性变形机制 基于文献中的实验结果。一种基于物理学的本构模型 模型涉及材料塑性和晶粒细化的基础上， 滑动和孪生机制，并成功地实施了一个 有限元（FE）分析与多个切削通道，以预测 通过纳米晶晶粒细化和其他方法 AZ31B镁合金深冷加工表面完整性的改善 合金通过更定量的评估，有限元模型结果进一步 讨论了晶粒细化、显微硬度变化、残余应力和 滑动/孪生机制，由于快速的 低温冷却
The use of magnesium (Mg) alloy has been continuously on the rise with numerous expanded application in transportation/aerospace industries due to their lightweight and other areas, such as biodegradable medical implants. It was shown recently that machining can be used to improve the functional performance of Mg-based products/components, such as corrosion resistance, through engineered surface integrity. In this paper, the behavior of AZ31B Mg alloy in cryogenic machining was discussed firstly. The surface integrity can be significantly improved by introducing the ultrafine grained (UFG) layer due to the severe plastic deformation (SPD) effect during cryogenic machining. The mechanisms of microstructure evolution and plastic deformation were analyzed based on the experimental findings in literature. A physics-based constitutive model involving material plasticity and grain refinement is developed based on both slip and twinning mechanisms and successfully implemented in a finite-element (FE) analysis with multiple cutting passes to predict the microstructure evolution by nanocrystalline grain refinement and other improvement of the surface integrity in the cryogenic machining of AZ31B Mg alloy. With a more quantitative assessment, the FE model results are further discussed for grain refinement, changes in microhardness, residual stresses, and slip/twinning mechanism with the apparent SPD taking place due to rapid cryogenic cooling.