高应变率复杂应变路径下车身高强钢的塑性变形行为研究

项目名称： 高应变率复杂应变路径下车身高强钢的塑性变形行为研究

项目编号： No.51205298

项目类型： 青年科学基金项目

立项/批准年度： 2013

项目学科： 机械工程学科

项目作者： 孟正华

作者单位： 武汉理工大学

项目金额： 25万元

中文摘要： 与普通低碳钢相比，车身高强钢室温成形性能较差。已有研究表明，高应变率复合成形等工艺可有效改善高强钢板成形性能。但在复合成形过程中，应变率及应变路径均发生改变，其对高强钢成形过程的影响机理尚不清楚。本项目系统研究车身高强钢在高应变率复杂应变路径下的塑性变形行为。通过准静态与动态高速拉伸试验，采用预变形-终变形方式并改变预应变大小及复合次序，测试分析不同应变率及应变路径下的应力应变关系；建立含有应变路径及应变率影响因子的本构模型；采用SEM、电子衍射分析材料微观组织变化以研究变形机理与失效模式；测试分析断裂应力-应变-应变率关系，建立合适的成形失效准则；采用普通冲压与电磁成形复合工艺并通过网格应变测试建立高应变率复合成形条件下材料成形极限图；采用CAE手段模拟电磁复合成形过程，对比模拟与实验结果以验证本构方程及失效准则正确性。项目研究结果将为车身高强钢先进成形工艺优化设计提供重要理论基础。

中文关键词： 高应变率；高强钢；应变路径；轻量化；塑性变形

英文摘要： Compared with normal steel, the auto-body high strength steel （HSS）has poorer formability at room temperature. The current research results show that the high strain rate hybrid forming can improve the formability of HSS. However, it is not clearly that the effects of the high strain rate and strain paths changes on the mechanism of HSS high strain rate hybrid forming. In this project, the plastic deformation behaviors of auto-body HSS at high strain rate and complex strain paths will be investigated systematically. Through combining with the quasi-static and dynamic high speed stretching tests and changing the way and the combine sequences of pre-deformation and end-deformation, the stress-strain relation at different strain rates and strain paths with different pre-strains will be measured and analyzed; the constitutive model including strain rate and strain path factors will be given out; the deformation mechanism and failure mode will be investigated by analyzing the microstructure transformation with SEM and electron diffraction; the fracture stress-strain-strain rate relation will be measured and analyzed in order to establish the suitable forming failure criteria; the forming limit diagrams under high strain rates hybrid forming conditions according to conventional stamping and electromagnetic hybrid for

英文关键词： High strain rate；High strength steel；Strain path；Lightweight；Plastic deformation