Ti微合金化对25Cr3Mo3NiNbZr钢碳化物析出行为和高温强度的影响  

Effect of Ti microalloying on carbide precipitation behavior and high temperature strength of 25Cr3Mo3NiNbZr steel

作　　者：卢茂勇 徐乐[2] 李浩 梁恩溥 李若浩 吴润[1] Lu Maoyong;Xu Le;Li Hao;Liang Enpu;Li Ruohao;Wu Run(School of Materials and Metallurgy,Wuhan University of Science and Technology,Wuhan Hubei 430081,China;Research Institute of Special Steels,Central Iron and Steel Research Institute Company Limited,Beijing 100081,China;Chongqing Chang'an Wangjiang Industrial Group Co.,Ltd.,Chongqing 400020,China)

机构地区：[1]武汉科技大学材料与冶金学院,湖北武汉430081 [2]钢铁研究总院有限公司特殊钢研究院,北京100081 [3]重庆长安望江工业集团有限公司,重庆400020

出　　处：《金属热处理》2023年第11期29-37,共9页Heat Treatment of Metals

基　　金：农机装备材料生产应用示范平台项目(TC200H01X/05)。

摘　　要：利用光学显微镜(OM)、扫描电镜(SEM)、透射电镜(TEM)、Thermo-Calc热力学计算、物理化学相分析和高温(700℃)拉伸试验,研究了Ti微合金化对25Cr3Mo3NiNbZr钢碳化物析出行为、微观组织和高温强度的影响。结果表明,由于添加了微合金化元素Ti,试验钢的原奥氏体晶粒由50μm细化至20μm,高温(700℃)抗拉强度提升176 MPa,高温屈服强度提升54 MPa。钢中MC型碳化物析出量明显增多,数密度由4.36×10^(15)m^(-3)提升至5.34×10^(19)m^(-3),且5~10 nm的MC型碳化物占比由81.8%提升至90.1%,同时增加了1~5 nm的MC析出相。此外,Ti元素的添加提高了MC型碳化物的热稳定性,粗化速率由0.301978 nm·s^(-1)/3降低到0.169049 nm·s^(-1)/3。添加Ti元素后,试验钢中的MC型碳化物更细小,分布更密集,热稳定性更好,是试验钢高温强度提高的主要原因。Effect of Ti microalloying on carbide precipitation behavior,microstructure and high temperature strength of the 25Cr3Mo3NiNbZr steel was investigated by means of optical microscope(OM),scanning electron microscope(SEM),transmission electron microscope(TEM),Thermo-Calc thermodynamic calculation,physicochemical phase analysis and high temperature(700℃)tensile test.The results show that due to the micro-addition of Ti,the prior austenite grain size of the tested steel is refined from 50μm to 20μm,the high temperature(700℃)tensile strength and yield strength are increased by 176 MPa and 54 MPa.After the addition of Ti,the number density of MC-type carbide in the steel increases from 4.36×10^(15) m^(-3)to 5.34×10^(19)m^(-3),and the proportion of MC-type carbide in the size of 5-10 nm increases from 81.8%to 90.1%,and the MC-type carbide in the size range of 1-5 nm also increases.In addition,due to the addition of Ti,the thermal stability of MC carbides is improved,and the coarsening rate is reduced from 0.301978 nm·s^(-1)/3 to 0.169049 nm·s^(-1)/3.The addition of Ti makes the MC-type carbide in the tested steel smaller in size,denser and more stable,which is the main reason for the improvement of the high temperature strength of the tested steel.

关 键 词：TI微合金化 高温强度 碳化物 析出行为 热稳定性 

分 类 号：TG142[一般工业技术—材料科学与工程]