(1. 中南大学 材料科学与工程学院,长沙 410083;
2. 中南大学 有色金属先进结构材料与制造协同创新中心,长沙 410083;
3. 中南大学 有色金属材料科学与工程教育部重点实验室,长沙 410083)
摘 要: 结合光学显微镜(OM)、电子背散射衍射技术(EBSD)等,研究分步锻压对AZ91镁合金变形过程中组织演化及性能的影响。采用室温拉伸实验检测分步锻后样品的力学性能,并将分步锻后样品的组织、性能同普通一步锻压工艺样品的进行了比较。结果表明:分步锻压工艺可有效促进动态再结晶的发生,锻压过程中流变应力明显降低,锻后组织细化效果明显,变形织构弱化,综合力学性能提升。在623 K下分步锻压后,样品的再结晶体积分数升高至95%,在保持高强度的同时,锻后样品的室温伸长率达到19.6%,与相同温度普通一步锻压后的样品相比提升了约53%。
关键字: AZ91镁合金;分步锻压;动态再结晶;力学性能
(1. School of Materials Science and Engineering, Central South University, Changsha 410083, China;
2. Nonferrous Metal Oriented Advanced Structural Materials and Manufacturing Cooperative Innovation Center, Central South University, Changsha 410083, China;
3. Key Laboratory of Nonferrous Materials Science and Engineering, Ministry of Education, Central South University, Changsha 410083, China)
Abstract:The effects of interrupted forging on the microstructural evolution of a cast AZ91 magnesium alloy were investigated by optical microscopy (OM) and electron back-scattering diffractometry (EBSD) and resultant mechanical properties were detected through tensile tests at ambient temperature. The results show that dynamic recrystallization (DRX) is remarkably accelerated and a decreased flow stress is observed under the condition of interrupted forging. Accordingly, there is an obvious grain refinement and the basal texture is weakened after interrupted forging, resulting in an improvement in mechanical property. As the volume fraction of dynamic recrystallized grains increases from 47% to 95% after interrupted forging at 623 K, the ambient tensile elongation of deformed sample increases by 53%, reaching the maximum of 19.6%, with little or no drop in strength.
Key words: AZ91 Mg alloy; interrupted forging; dynamic recrystallization; mechanical properties