基本信息
项目批准号：51805145
申请代码：E0508
项目名称：{10-12}孪晶改善变形镁合金搅拌摩擦焊接头强塑性的机制研究
项目负责人：许楠
依托单位：河海大学
研究期限：2019-01-01 至 2021-12-31
资助经费：25.0（万元）
项目摘要
中文摘要：
对变形镁合金搅拌摩擦焊(FSW)接头进行有效的强塑化设计是镁合金焊接领域的研究热点，其难题在于接头极易形成强烈的基面织构，降低接头的屈服强度和延伸率。申请人提出的大载荷超低速FSW工艺可在接头制备{10-12}孪晶，促进基面织构弱化和晶粒细化，显著改善强塑性，但{10-12}孪晶对接头强塑化的作用机制尚不明确。本项目拟探索发生{10-12}孪生行为的临界Zener-Hollomon指数，阐明其与塑性变形主导机制的内在关联；研究滑移、孪生以及滑移-孪生交互作用对再结晶行为和晶粒取向的影响，揭示接头微观组织和织构演变规律；研究接头微观组织和织构对拉伸性能、裂纹萌生与扩展和失效机制的影响规律，揭示{10-12}孪晶改善变形镁合金FSW接头强塑性的机制。本项目研究结果既可完善孪晶界改善镁合金综合力学性能的相关理论，也为大载荷超低速FSW在镁合金大型复杂结构件制造上的实际应用提供理论指导和设计依据。
英文摘要：
For the joining of Mg alloys, effective strength-ductility synergy design of friction stir welded (FSW) wrought Mg alloy joint is a hotspot. The problem is that a strong base texture usually formed in the joint, and thus deteriorates the strength and ductility of the joint. The large-load low-speed FSW (LL-FSW) process which developed by authors can produce {10-12} twins in the joint. {10-12} twinning behavior can randomize the base texture and refine the grain structure, and thus significantly improves the strength and ductility of the joint. However, the effect of {10-12} twinning behavior on the strength and ductility of the joint is not yet clear. This project aims to calculate the critical Zener-Hollomon parameter of the {10-12} twinning behavior, and clarify the relationship between the Zener-Hollomon parameter and the main mechanism of the plastic deformation; research the influence of dislocation slipping, twinning and slipping-twinning interaction on the recrystallization behavior and grain orientation, and reveal the microstructure and texture evolution during the FSW process; investigate the effect of microstructure and texture on the tensile properties, the crack initiation and propagation and failure mechanism of the joint, explore the effect of the {10-12} twinning behavior on the strength and ductility modification mechanism of the FSWed wrought Mg alloy joint. This project can further improve the theory of "mechanical properties' modification of Mg alloys using twin boundaries", and also provides theoretical guidance and design basis for the practical application of LL-FSW in the manufacture of large complicated Mg alloy components.
                                                                                                                                                                                                         ——来自https://kd.nsfc.gov.cn/