高温下灰铸铁微观组织的演变及其对抗拉强度的影响  

Microstructure Evolution of Gray Cast Iron at High Temperature and Its Effect on Tensile Strength

作　　者：杜瑞 薛正良[1] 严浩 周小勇 DU Rui;XUE Zhengliang;YAN Hao;ZHOU Xiaoyong(Wuhan University of Technology, Hubei Metallurgical Secondary Resources Engineering Technology Research Center, Wuhan Hubei 430081, China;Hubei Yemao Technology Co., Ltd., Xiangyang Hubei 441800, China)

机构地区：[1]武汉科技大学湖北省冶金二次资源工程技术研究中心,湖北武汉430081 [2]湖北业茂科技有限公司,湖北襄阳441800

出　　处：《上海金属》2021年第1期20-25,共6页Shanghai Metals

基　　金：产学研项目(No.51874214)。

摘　　要：灰铸铁刹车毂在行车过程中因连续刹车导致温度快速升高而过早失效。采用高温拉伸试验机和室温拉伸试验机分别对灰铸铁试样进行室温和高温拉伸试验,利用光学显微镜和扫描电镜观察不同温度拉伸后试样的微观组织,研究了灰铸铁的微观组织演变规律及其对高温抗拉强度的影响。结果表明:当拉伸试验温度从室温升高到200℃时,石墨形态变化不大,珠光体片层间距增大,抗拉强度下降幅度不大;当温度升高到500和700℃时,石墨片有粗化的倾向,石墨团聚数量增加,珠光体片层间距明显增大,同时部分渗碳体片发生断裂、溶解,转变成细粒状结构。高温下灰铸铁微观组织的变化导致其抗拉强度明显下降,800℃时的抗拉强度仅为室温下的17.2%。Gray cast iron brake hub failed prematurely due to the rapid temperature rise caused by continuous braking during driving.The high-temperature and room-temperature tensile tests of the gray cast iron specimens were carried out on a high-temperature tensile tester and a normal-temperature tensile tester,respectively.The change in microstructure of the specimens tension tested at different temperatures was observed by optical microscope and scanning electron microscope.The microstructure evolution of gray cast iron and its effect on high temperature tensile strength were studied.The results showed that when the tensile test temperature increased from room temperature to 200℃,the graphite form changed a little,the pearlite interlamellar spacing increased,and the tensile strength decreased a little;when the temperature increased to 500 and 700℃,the graphite flake tended to coarsen,the number of graphite agglomerations increased,and the interlamellar spacing of pearlite increased significantly,at the same time,some of the cementite lamellae fractured and dissolved into fine-grained structures.The tensile strength of gray cast iron decreased obviously due to the change of microstructure at high temperature,and the tensile strength at 800℃was only 17.2%of that at room temperature.

关 键 词：刹车毂 灰铸铁 高温抗拉强度 珠光体 

分 类 号：TG1[金属学及工艺—金属学]