22MnB5钢溶质分配系数及TiN析出对微观偏析的影响  

Effect of solute partition coefficient and TiN precipitation on micro-segregation of 22MnB5 steel

作　　者：郭伟 龙木军[1,2] 吴家璐[1,2] 张浩浩 艾松元 陈登福 GUO Wei;LONG Mu-jun;WU Jia-lu;ZHANG Hao-hao;AI Song-yuan;CHEN Deng-fu(School of Materials Science and Engineering,Chongqing University,Chongqing 400044,China;Chongqing Key Laboratory of Vanadium and Titanium Metallurgy and New Materials,Chongqing University,Chongqing 400044,China)

机构地区：[1]重庆大学材料科学与工程学院,重庆400044 [2]重庆大学钒钛冶金及新材料重庆市重点实验室,重庆400044

出　　处：《钢铁》2022年第3期44-54,共11页Iron and Steel

基　　金：国家自然科学基金资助项目(U1960113,51874059)。

摘　　要：为了提高凝固过程中溶质微观偏析模型计算的准确性,基于溶质分配系数及夹杂物析出对溶质偏析的重要影响,定量分析了溶质分配系数以及TiN析出对凝固过程溶质元素含量的影响,为微合金高强钢凝固过程研究提供理论参考。针对22MnB5钢建立了耦合TiN析出热力学模型的溶质微观偏析模型,并探究了温度及钢液凝固路径对溶质分配系数的影响规律,结果表明,相转变对k_(Ti)(钛的分配系数)和k_(N)(氮的分配系数)的影响均大于温度对其的影响。当固相率为0.74时,发生L+δ向L+γ相转变,k_(Ti)由0.26降低至0.20,钛元素的偏析程度提高;k_(N)由0.30增加至0.46,氮元素的偏析程度降低。偏析促使TiN在固相率fs为0.43时开始析出,在未考虑TiN析出对微观偏析的影响时,凝固末期液相中Ti、N元素的质量分数分别为0.286%、0.0056%;而在考虑TiN析出的影响时,凝固末期液相中Ti、N元素的质量分数分别为0.237%、0.0019%,分别降低了17.1%和66.0%。同时由于凝固过程中钛的偏析程度较高,钛在凝固前沿的富集足以抵消TiN沉淀的消耗,而钢中初始氮的质量分数较低,并且氮元素的偏析趋势随着凝固进程减弱,在L+δ向L+γ相转变影响下也降低了溶质氮的偏析程度,所以溶质氮在凝固前沿的偏析现象不足以抵消TiN沉淀的消耗。因此凝固前沿液相中氮的质量分数受TiN析出影响由上升转为明显下降,而钛的偏析程度仅在凝固末期出现减弱。In order to improve the micro solute segregation in solidification process the accuracy of the model calculation,based on the solute distribution coefficient and the inclusion of the important influence to the solute segregation,this study quantitatively analyses the solute distribution coefficient and separation effect on solidification process of solute elements content of TiN,provide theoretical reference for the research on high strength steel solidification process of micro alloy.A solute microsegregation model coupled with TiN precipitation thermodynamic model was established for 22MnB5 steel,and the effects of temperature and solidification path on solute distribution coefficient were investigated.The results show that the phase transition has greater effects on k_(Ti)(titanium distribution coefficient)and k_(N)(nitrogen distribution coefficient)than the temperature.When the solid phase ratio is 0.74,the phase transition from L+δto L+γoccurs,k_(Ti) decreases from 0.26 to 0.20,and the degree of titanium segregation increases.k_(N) increased from 0.30 to 0.46,and the degree of nitrogen segregation decreased.When the solid phase ratio fs is 0.43,TiN begins to precipitate.When the effect of TiN precipitation on microstructure segregation is not considered,the mass percent of Ti and N in the liquid phase at the end of solidification is 0.286%and 0.0056%,respectively.When TiN precipitation is considered,the mass percent of Ti and N in the liquid phase at the end of solidification are 0.237%and 0.0019%,which decrease by 17.2%and 66.9%,respectively.At the same time,due to the high degree of titanium segregation during solidification,the enrichment of titanium at the solidification front is enough to offset the consumption of TiN precipitation,while the mass percent of initial nitrogen in steel is low,and the trend of nitrogen segregation decreases with the solidification process,and the degree of solute nitrogen segregation is also reduced under the influence of the transformation from L+δto L+γphase.So the se

关 键 词：22MnB5 微观偏析 溶质分配系数 TiN析出 热力学 

分 类 号：TG142.1[一般工业技术—材料科学与工程]