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晶界弹粘塑性变形损伤是钛合金超塑性成形和等温时效成形过程中的主要变形机制。文章考虑晶界的粘滞性及由其引起的率敏感性,建立弹粘塑性的晶界变形损伤本构模型,并结合Cohesive晶界单元描述晶界在钛合金低应变速率变形中的响应,实现对钛合金晶界的粘滞性滑移与迁移的合理描述。基于ABAQUS/Explicit平台,利用所建模型对不同应变速率10-3s-1、10-2s-1和10-1s-1下工业纯钛TA1单向拉伸过程中的晶界滑移行为进行有限元数值模拟分析。结果表明,当晶界厚度由0.8μm增大至1.2μm时,其临界强度降低,且晶界滑移对塑性变形的贡献增大近两倍;当应变速率为10-2s-1和10-3s-1、对应塑性应变为0.1时,晶界滑移对塑性应变的贡献分别是应变速率为10-1s-1时的10倍和20倍。
Grain boundary elastic viscoplastic deformation damage is the main deformation mechanism of titanium alloy superplastic forming and isothermal aging forming process. In this paper, the constitutive model of grain boundary deformation damage is established considering the viscosity of the grain boundary and the rate sensitivity caused by the deformation. The Cohesive grain boundary element is used to describe the response of the grain boundary to the low strain rate deformation of the titanium alloy. To achieve a reasonable description of the viscosity slip and migration of the titanium alloy grain boundaries. Based on the ABAQUS / Explicit platform, the grain boundary slip behavior during the uniaxial stretching of industrial pure titanium with different strain rates of 10-3s-1, 10-2s-1 and 10-1s-1 Meta-numerical simulation analysis. The results show that when the grain boundary thickness increases from 0.8μm to 1.2μm, the critical strength decreases, and the contribution of grain boundary slip to plastic deformation increases nearly twice. When the strain rate is 10-2s-1 and 10- 3s-1, corresponding to the plastic strain of 0.1, the contribution of the grain boundary slip to the plastic strain is 10 times and 20 times respectively when the strain rate is 10-1s-1.