Mo对Nb-V-N微合金钢复合碳氮化物析出行为的影响  

Effect of Mo on precipitation behavior of composite carbonitrides in Nb-V-N microalloyed steel

作　　者：侯蹬云 张婧[1] 辛文彬 赵志博 彭军[1] 童炀 HOU Dengyun;ZHANG Jing;XIN Wenbin;ZHAO Zhibo;PENG Jun;TONG Yang(School of Rare Earth Industry(School of Rare Earth Engineering and Technology),Inner Mongolia University of Science and Technology,Baotou 014010,Nei Mongol,China)

机构地区：[1]内蒙古科技大学稀土产业学院(稀土工程技术学院),内蒙古包头014010

出　　处：《钢铁》2024年第8期104-116,共13页Iron and Steel

基　　金：国家自然科学基金资助项目(52104333);内蒙古自治区高等学校碳达峰碳中和研究专项资助项目(STZX202316);内蒙古自治区高等学校青年科技英才支持计划资助项目(NJYT24070);内蒙古自治区自然科学基金资助项目(2024MS05029)。

摘　　要：钢中微合金碳氮化物的析出行为与其强度直接相关,为揭示Nb-V-Mo-N四元微合金钢中MX(M为Nb、V、Mo,X为C、N)复合碳氮化物的析出规律,通过Thermo-Calc热力学计算软件分析了平衡条件下不同Mo含量微合金钢的析出热力学相图,MX第二相在奥氏体和铁素体基体相中的析出驱动力、界面能及合金元素在奥氏体中的固溶规律,并利用场发射扫描电镜、透射电镜及电子探针研究了非平衡条件下试验钢中MX碳氮化物的析出特征。结果表明,0Mo钢中MX碳氮化物主要有FCC_A1#1富Nb高温析出相和FCC_A1#2富V中温析出相,0.26Mo和0.50Mo钢则在此基础上增加了MC_ETA即(V,Mo)C低温析出相;当Mo质量分数由0增加到0.50%时,FCC_A1#1和FCC_A1#2相的析出温度和最大析出量变化不明显,但有利于MC_ETA相析出。非平衡条件下,高温奥氏体区析出的富Nb-MX亚微米颗粒能够在钉扎晶界的同时,异质形核诱导针状铁素体形成;中温(奥氏体+铁素体)两相区相间析出和低温铁素体区任意析出的富V-MX纳米颗粒可与位错相互作用,有效阻碍其运动。此外,0Mo试验钢的室温组织由块状铁素体和珠光体组成,当Mo质量分数由0增加到0.26%时,钢中块状铁素体和珠光体所占比例减少,但促进了针状铁素体和少量贝氏体形成,当Mo质量分数进一步增加到0.50%时,铁素体占比明显减少而贝氏体增多;铁素体晶粒尺寸由(10.2±0.42)μm不断细化至(6.7±0.42)μm。试验钢的显微硬度由(223±13.8)HV0.1逐渐增大至(318±19.9)HV0.1,屈服强度和抗拉强度分别由(496±5.3)MPa和(618±9.7)MPa提高至(554±6.7)MPa和(823±13.3)MPa。通过发挥Nb-V-Mo-N四元微合金体系中各合金元素的协同作用,优化MX碳氮化物的析出,有利于提升工程结构用钢的强度。The precipitation behavior of microalloyed carbonitrides in steel is directly related to its strength.For the purpose of revealing the precipitation rule of MX(M=Nb,V and Mo;X=C and N)composite carbonitrides in Nb-V-Mo-N quaternary microalloyed steels with different Mo contents,the precipitation thermodynamic phase diagram,driving force and interfacial energy of MX second phase in austenite and ferrite matrix,as well as the solid solution rule of alloying elements in austenite under the equilibrium condition were calculated using Thermo-Calc software.Besides,the precipitation characteristics of MX carbonitrides under non-equilibrium condition were also studied by field emission scanning electron microscope,transmission electron microscope and electron probe microscope analyzer.The results showed that the MX phases in the 0Mo steel were Nb-rich high-temperature precipitates(FCC_A1#1)and V-rich intermediate-temperature precipitates(FCC_A1#2).The(V,Mo)C low-temperature precipitates(MC_ETA)were also formed in 0.26Mo and 0.50Mo steels.With increasing Mo content from 0 to 0.50%,the precipitation temperature and the maximum precipitation amount of FCC_A1#1 and FCC_A1#2 did not change significantly,whereas the precipitation of MC_ETA phase was promoted.Moreover,the submicron Nb-rich MX particles precipitated in the high-temperature austenite region could pin the grain boundaries and induce the heterogeneous nucleation of acicular ferrite.The nanosized V-rich MX particles interphase precipitated in the intermediate-temperature two-phase region and randomly precipitated in the low-temperature ferrite region interacted with dislocations and effectively hindered their movement.In addition,the microstructure of 0Mo experimental steel at room temperature was composed of polygonal ferrite and pearlite.With increasing Mo content from 0 to 0.26%,the proportions of polygonal ferrite and pearlite were decreases,promoting the formation of acicular ferrite and a small amount of bainite.When the Mo content further increased to 0.50%,t

关 键 词：Nb-V-Mo-N微合金体系 工程结构用钢 MX复合碳氮化物 显微组织 力学性能 

分 类 号：TG142.33[一般工业技术—材料科学与工程]