钢铁材料中形变诱导相变超细化机理研究

通过计算机编程建立奥氏体相中121 1 0]刃位错、奥氏体相中非形变区和形变区奥氏体/铁 素体相界模型.用实空间的连分数方法计算了非形变区和形变区奥氏体/铁素体相界界面能， 计算了碳、氮及微合金元素在完整晶体及位错区引起的环境敏感镶嵌能，进而讨论形变过程 中铁素体形核的难易程度，碳、氮及合金元素在位错区的偏聚及析出与铁素体细化的关系. 计算结果表明：α-Fe易于在高密度位错区（形变带、亚晶界、晶界）形核，在奥氏体形变 过程中，就会大大提高α-Fe形核率，细化铁素体晶粒；碳、氮和微合金元素易于单独或共 同 关键词： 奥氏体/铁素体相界 刃位错 形变 晶粒细化

The study on the ultrafine mechanism of steels: strain-induced phase-transform ation form austenite to ferrite

The models of interphase boundaries of austenite/ferrite(γ/α) in the undeformde austenite and deformed austenite, and the model of 121 1 0] edge dislocation in austenite matrix were set up with computer programming. The interfacial energ y of γ/α interphase boundaries in the undeformde austenite and deformed austen ite, the environment sensitive embedding energies (EESE_ESE) of C, N a nd microalloying elements Nb, Ti or V (in the form of air mass) in the area of e dge dislocation in austenite were calculated by using recursion method. The refineme nt mechanism of steels in the deformation process was discussed. Interfacial ene rgy calculation results show that the most preferred ferrite nucleation sites ar e the area of high density dislocations such as deformation bands, the austenite grain boundaries and subbounaries, which leads to a considerable increase in th e nucleation rate. This is why ferrite grains formed in the deformed austenite a re far more smaller than those in undeformed austenite. The EESE_ESE calcu lation results show that C,N microalloying elements (Nb, Ti or V) in form of the air mass, C,N together with microalloying elements (Nb or Ti) in the form air m ass are all easy to aggregate to the area of edge dialocations, which results in the carbonitride precipitation in there (deformation band, grain boundary or gr ain subboundary). The growth of ferrite grains is considerably suppressed by def ormation due to impingement with carbonitride particles and other ferrite grains , which leads to the further refinement of ferrite grains.