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利用挤压成形工艺在300℃下将AZ31镁合金铸锭挤制为细晶板材,将制成的拉伸试样在250℃下分别以不同的应变速率进行等应变速率拉伸,研究了试样的超塑性变形性能,采用光学显微镜和扫描电镜分别观察了变形后试样的显微组织和断口形貌。研究结果表明,在250℃和2×10-2s-1应变速率下,AZ31镁合金试样的伸长率达到了290%,实现了较低温度和较高应变速率下的超塑性变形,有利于节约能源和提高效率;在250℃下以2.5×10-4s-1应变速率进行拉伸变形,试样的伸长率最大,达到了390%,最大伸长率下AZ31镁合金的显微组织显示,变形后试样的晶粒仍保持等轴状,但晶粒尺寸比原始晶粒增大约一倍,试样断口形貌表现为典型的韧窝型穿晶断裂特征。
The AZ31 magnesium alloy ingot was extruded at 300 ℃ into a fine-grained sheet by extrusion process. The tensile specimens were stretched at 250 ℃ for different strain rates at different strain rates. Like superplastic deformation performance, the optical microscopy and scanning electron microscopy were observed after deformation of the sample microstructure and fracture morphology. The results show that at 250 ℃ and 2 × 10-2s-1 strain rate, the elongation of AZ31 magnesium alloy reaches 290%, and the superplastic deformation at lower temperature and higher strain rate is achieved. There are Conducive to energy conservation and improve efficiency; tensile deformation at 250 ℃ at a strain rate of 2.5 × 10-4s-1, the maximum elongation of the sample reached 390%, the maximum elongation AZ31 magnesium alloy microstructure Tissue shows that the grain size of the specimen remains equiaxed after deformation, but the grain size increases about twice as that of the original grain. The fracture morphology of the specimen shows typical dimple-type transgranular fracture characteristics.