扩收挤压成形的AZ80镁合金轮毂高周疲劳性能  

High Cycle Fatigue Properties of AZ80 Magnesium Alloy Wheels Hub Formed by Expansion-Reduced Extrusion

作　　者：王珺[1,2,3] 车鑫[1] 杨勇彪[1] 张治民 耿立业[4] 王强[1] WANG Jun;CHE Xin;YANG Yongbiao;ZHANG Zhimin;Geng Liye;WANG Qiang(College of Materials Science&Engineering,North University of China,Taiyuan 030051,China;State Key Laboratory of Advanced Stainless Steel Materials,Taiyuan Iron&Steel(Group)Co.,Ltd.,Taiyuan 030003,China;Technology Center,Shanxi Taigang Stainless Steel Co.,Ltd.,Taiyuan 030003,China;Foundry of Shanxi Diesel Engine Industries Co.,Ltd.,Datong 037036,China)

机构地区：[1]中北大学材料科学与工程学院,山西太原030051 [2]太原钢铁(集团)有限公司先进不锈钢材料国家重点实验室,山西太原030003 [3]山西太钢不锈钢股份有限公司技术中心,山西太原030003 [4]山西柴油机工业有限责任公司铸造厂,山西大同037036

出　　处：《热加工工艺》2022年第3期17-21,25,共6页Hot Working Technology

基　　金：国家重点研发计划项目(2016YFB0301103-3)。

摘　　要：采用新型的扩收挤压工艺和传统挤压工艺分别成形AZ80镁合金轮毂,利用Instron8801疲劳实验机测试室温高周疲劳性能,用金相显微镜分析两种工艺成形过程各阶段的组织,用扫描电子显微镜观察了扩收挤压工艺高周疲劳试样的断口形貌。结果表明:得益于动态再结晶和较高的等效应变,扩收挤压成形的轮辐部位主要呈现出均匀的等轴晶微观组织,平均晶粒尺寸为11μm,远小于传统挤压工艺的28μm。在应力比R=-1、循环次数为10^(7)的条件下,扩收挤压成形轮毂的疲劳强度为129.7 MPa,比传统挤压工艺的提高4 MPa。轮毂试样的疲劳裂纹主要萌生于表面的缺陷处;裂纹扩展区域有较少的解理面、韧窝和撕裂棱,出现疲劳辉纹;瞬断区由少量的韧窝和较多的解理台阶组成。The AZ80 magnesium alloy wheel hubs were formed by the new expansion-reduced extrusion(ERE)process and the traditional extrusion(TE) process respectively. The high cycle fatigue performance was tested by Instron8801 fatigue testing machine at room temperature. The microstructure at each stage of the two processes was analyzed by metallographic microscope. And the fracture morphologies of the high cycle fatigue samples produced by the ERE process were observed by SEM. The results show that due to the dynamic recrystallization and high equivalent strain, the wheel spokes formed by the ERE show almost uniform equiaxed structure, with an average grain size of 11 μm, which is far lower than 28 μm of the TE process. Under the condition of stress ratio R=-1 and number of cycles 10^(7), the fatigue strength of the wheel hubs formed by ERE is 129.7 MPa, which increase 4 MPa compared with that of the TE process. The fatigue cracks of the wheel hub specimen are mainly initiated at the defects of the surface;there are a few cleavage planes, dimples and tearing edges in the crack propagation region, and fatigue glow lines appear;the transient fracture region consists of a small number of dimples and more cleavage steps.

关 键 词：AZ80镁合金 轮毂 扩收挤压 高周疲劳 微观组织 

分 类 号：TG379[金属学及工艺—金属压力加工] TG146.22[一般工业技术—材料科学与工程]