Ce对于20MnTiB冷镦钢夹杂物和力学性能的影响  

Effect of Ce on inclusions and mechanical properties of 20MnTiB cold heading steel

作　　者：樊轩宇 于彦冲[1] 郑安民 薛高红 张金玲[1] 王社斌[1] FAN Xuanyu;YU Yanchong;ZHENG Anmin;XUE Gaohong;ZHANG Jinling;WANG Shebin(College of Materials Science and Engineering,Taiyuan University of Technology,Taiyuan 030024,China;Shanxi Xintai Iron and Steel Co.Ltd.,Jiexiu 032000,China;Shanxi Gaoyi Iron and Steel Co.Ltd.,Linfen 043100,China)

机构地区：[1]太原理工大学材料科学与工程学院,太原030024 [2]山西新泰钢铁有限公司,介休032000 [3]山西高义钢铁有限公司,运城043100

出　　处：《工程科学学报》2024年第11期1989-1999,共11页Chinese Journal of Engineering

基　　金：国家自然科学基金资助项目(52004180,52204350);中国博士后科学基金资助项目(2020M683706XB);山西省回国留学人员科研资助项目(2023-080)。

摘　　要：工业化试验生产不同稀土(Ce)含量20MnTiB冷镦钢,采用维氏硬度计、拉伸试验机、冲击试验机、光学显微镜(OM)及扫描电镜(SEM)等手段,研究添加Ce后,钢中夹杂物变质情况以及热轧盘条显微组织和力学性能的变化,并分析Ce的作用机理.结果表明,添加0.0025%Ce后,钢液中S含量下降,洁净度显著提高;盘条中夹杂物由大尺寸、长条状的Al_(2)O_(3)·MgO·CaO·CaS复合夹杂物变质为小尺寸、类球状的CeAlO_(3)·MgO·CaO·CaS复合夹杂物;同时长条状MnS夹杂物消失;热力学计算表明钢中最易生成的稀土夹杂物为CeAlO_(3).添加Ce后,盘条显微组织细化,铁素体比例有所提升,粒状贝氏体组织减轻,其尺寸也进一步减小.盘条的硬度、屈服强度和抗拉强度有所降低;室温冲击韧性显著增加,由31.7 J增加至52.3 J,提升65.0%.稀土微合金化盘条硬度、强度的降低以及冲击性能的显著增加有益于其冷镦性能提高.研究结果可为进一步开发新型稀土微合金化冷镦钢提供技术和理论支撑.Industrialized tests are conducted to produce 20MnTiB cold heading steel with varying Ce contents.A Vickers hardness tester,tensile tester,impact tester,optical microscope,and scanning electron microscope are used to study the deterioration of inclusions in the steel and observe the changes in microstructure and mechanical properties of the hot-rolled wire rod after Ce addition.The application mechanism of Ce is also analyzed.The results show that the S content in the molten steel decreases,and the cleanliness is significantly improved after the addition of 0.0025%Ce.The inclusions in the wire rod transform from large-sized and elongated Al_(2)O_(3)·MgO·CaO·CaS composite inclusions to small-sized and spherical CeAlO_(3)·MgO·CaO·CaS composite inclusions.Concurrently,the long strips of MnS inclusions disappear.Thermodynamic calculations indicate that at 1839 K,the order of precipitation of different Ce inclusions is as follows:CeAlO_(3)>Ce_(2)O_(3)>Ce_(2)O_(2)S>CeO_(2)>Ce_(3)S_(4)>Ce_(2)S3>CeS.This suggests that with a Ce mass fraction of 0.0025%,the most probable inclusions are CeAlO_(3).Considering that 20MnTiB cold heading steel contains B,Ti,and other hardenability elements,improper process control during hot rolling can easily lead to the formation of a bainite structure in the wire rod.This causes the mechanical strength of the wire rod to be higher than desired,leading to occasional cracking during late cold heading and significant wear on the cold heading mold.After the addition of Ce,the microstructure of the wire rod is refined,with an increased proportion of ferrite and a reduction in both the presence and size of granular bainite.Ferrite is a soft and tough phase,while bainite is a reinforcing phase.The reduction in granular bainite and the increase in ferrite contribute to a decrease in strength and hardness.Lower hardness and strength are beneficial for improving the cold heading performance of the wire rod.After Ce addition,the cold heading performance of the wire rod is improved to a certain e

关 键 词：稀土 夹杂物 20MnTiB冷镦钢 粒状贝氏体 冲击韧性 

分 类 号：TG142.1[一般工业技术—材料科学与工程]