摘要
钢中加入的微合金元素钒、铌、钛等,可以与钢中的碳、氮元素结合,起到沉淀强化及细晶强化作用,从而改善钢的综合性能。为了研究钒对高碳车轮钢组织及力学性能分布的影响,用200 kg真空炉冶炼了2炉碳质量分数为0.60%左右的试验钢,钒质量分数分别为0及0.07%,试验钢热处理方式均模拟现场且工艺保持一致。热处理后,用光学显微镜进行微观组织形貌观察及铁素体体积分数分析;用扫描电子显微镜进行拉伸断口、珠光体片层间距观察;用EBSD进行珠光体团尺寸分析;用透射电镜对析出物形貌进行分析;并对试验钢力学性能进行测试。结果表明,添加钒可以使表面下相同深度处铁素体体积分数增加1.7%~4.8%,标准差降低6.1%~72.5%,且相邻深度处铁素体体积分数变化更小,组织均匀性更好;使珠光体团尺寸更加细小,小角晶界(5°~15°)数量明显增多,使表面下相同深度处平均晶粒度提高约0.5级,标准差降低9%~17%,晶粒大小更加均匀,且基本不影响相邻深度处奥氏体晶粒度变化;使表面下相同深度处珠光体片层间距减小约20%,标准差降低10%~17%,且略微降低相邻深度处珠光体片层间距梯度变化;提高表面下相同深度处抗拉强度约为12%、屈服强度约为25%、硬度约为10%、冲击功为9%~25%,且降低相邻深度处硬度梯度,使得试验钢硬度均匀性更好及冲击功波动更小;对塑性影响不大。
The microalloy elements V,Nb and Ti added to the steel can combine with the C and N elements in the steel to play the role of precipitation strengthening and fine grain strengthening,thus improving the overall performance of the steel.In order to study the effect of V on microstructure and mechanical property distribution of high-carbon wheel steel,two heats of test steel with the mass percent of C of about 0.60%were smelted in a 200 kg vacuum furnace,and the mass percent of V was 0 and 0.07%respectively.The heat treatment simulated field production and the process remained consistent.After heat treatment,microstructure morphology observation and ferrite volume percent analysis were carried out by optical microscope.Tensile fracture and pearlite lamellae spacing observation were carried out by scanning electron microscope.Pearlite cluster size analysis was carried out by EBSD.The morphology of precipitates was analyzed by transmission electron microscopy.The mechanical properties of the test steel were tested.The results show that the addition of V can increase the ferrite volume percent at the same depth under the surface by 1.7%-4.8%,and the standard deviation is reduced by 6.1%-72.5%,and the ferrite volume percent at the adjacent depth changes less,and the microstructure uniformity is better.It can make the size of pearlite cluster finer and the number of small angular grain boundaries(5°-15°)increase significantly,so that the average grain size at the same depth under the surface is increased by about 0.5 grade,the standard deviation is reduced by 9%-17%,and the grain size is more uniform,which basically does not affect the change of austenite grain size at adjacent depths.V can make the pearlite layer spacing at the same depth under the surface reduced by about 20%and the standard deviation reduced by 10%-17%,and slightly reduce the gradient change of pearlite layer spacing at the adjacent depth.Element V can improve the tensile strength about 12%,yield strength about 25%,hardness about 10%,impact energy 9%-25%at the same depth under the surface,and reduce the hardness gradient at adjacent depths,which makes the test steel hardness uniformity better and impact energy fluctuation smaller.It has little effect on plasticity.
作者
万志健
赵海
刘学华
张建
WAN Zhi-jian;ZHAO Hai;LIU Xue-hua;ZHANG Jian(National-Local Joint Engineering Research Center of Advanced Manufacturing Technology for Key Parts of Rail Transit,Maanshan 243000,Anhui,China;Key Parts of Rail Transit Technology Innovation Center of Anhui Province,Maanshan 243000,Anhui,China;Maanshan Iron and Steel Co.,Ltd.,Maanshan 243000,Anhui,China)
出处
《钢铁》
CAS
CSCD
北大核心
2023年第5期104-111,共8页
Iron and Steel
基金
安徽省科技重大专项资助项目(202003a05020038)。
关键词
钒
珠光体车轮钢
组织
力学性能
变化
vanadium
pearlitic wheel steel
microstructure
mechanical property
variation
