摘要
铌可以显著改善钢的组织,提高钢的性能。同时,铌在钢中还存在偏聚现象,可有效提高钢的淬透性,使共析点右移。因此,利用金相法和等温热处理试验,对高碳钢的微观组织进行分析,发现铌的析出和固溶将细化晶粒,同时铌的加入将推迟高碳钢的珠光体转变,并使其孕育期延长。利用合金价电子结构理论,构建了不含铌和含铌的两种体系的奥氏体合金价电子晶胞,从电子层次研究铌对高碳钢奥氏体的影响规律。理论计算结果表明,两种模型在碳质量分数为0.86%时的最大共价电子对数nA分别为0.972 5、0.962 4。铌的加入会改变体系中键的组成,并与碳原子结合形成新的最强键C-Nb键。而NbC的析出阻碍了碳在奥氏体中的扩散,推迟了珠光体的形成和长大,进而推迟了珠光体相变,导致添加铌元素后的CCT曲线右移。
Niobium can significantly ameliorate the structure and improve the performance of steel.At the same time,Nb was also segregation in the steel,which can effectively increase the steel hardenability,shifting the eutectoid point to the right.Therefore,the metallographic method and isothermal heat treatment experiments were used to analyze the microstructure of high carbon steel.It was found that the precipitation and solid solution of Nb would refine the grains,and the addition of Nb would delay the pearlite transformation of high carbon steel and make it.The incubation period was extended.Valence electron cells of two austenite alloys Nb free atoms and Nb atoms were constructed by using empirical electron theory(EET)of solids and molecules,to revealed the Nb on austenite influence from the electronic level.Theoretical results shown that the maximum covalent logarithmic logarithmnAof the two models under 0.86%carbon mass percent were 0.972 5 and 0.962 4,respectively.The addition of Nb would changes the composition of the bonds in the system and combine with C atoms to form new strongest bond C-Nb bonds,thus explained the principle of the formation of NbC.The precipitation of NbC hinders the diffusion process of C in austenite,which delays the formation and growth of pearlite,and directly delays the phase transformation of pearlite,resulted in the CCT moving to the right after the addition of Nb.
作者
刘铖霖
曹建春
周煌
高鹏
阴树标
叶亚平
LIU Cheng-lin;CAO Jian-chun;ZHOU Huang;GAO Peng;YIN Shu-biao;YE Ya-ping(School of Materials Science and Engineering,Kunming University of Science and Technology,Kunming 650093,Yunnan,China;School of Metallurgy and Energy Engineering,Kunming University of Science and Technology,Kunming 650093,Yunnan,China)
出处
《钢铁》
CAS
CSCD
北大核心
2019年第11期101-109,共9页
Iron and Steel
基金
中信金属宁波能源有限公司的资金与服务支持
关键词
高碳钢
晶粒细化
合金价电子结构
奥氏体
铌
high-carbon steel
grain refinement
alloy valence electron structure
austenite
niobium
