摘要
本文提出了淬火钢中常见的(111)r,(225)r及“隐晶”等三种马氏体形态变化的临界现象的数学模式.诸形态均存在各自的原始奥氏体临界晶粒直径D_c与奥氏体中临界固溶碳原子浓度C_c的数学关系D_c^(-1/2)=((τ_s^e)/k-(140/k)C_c)形态给定时,奥氏体的临界切变屈服强度τ_s^c及Hall-petch斜率k均为定值,并可用它们标识形态变化的临界现象.实验已初步证实此模式的可靠性,并测定了诸形态的τ_s^c及k值.对诸形态k值分析表明,(111)r与(225)r马氏体均为晶界源位错形核,但柏氏矢量前者仅为后者的一半.“隐晶”马氏体形核不但包括晶界位错源模式,还包括切模量降低的、很可能是“局部较模”这种形核模式.这使核密度显著增加,从而形成“隐晶”态马氏体.
The mathematical model of the critical phenomenons of the martensitic morphological variations for three common kinds of martensite, (111)r, (225)r and 'cryptocrystallin' martensites in steels, is advanced. For each morphology the methematical relationship between the critical prior austenite grain size Dc and thecritical splid solubility of carbon Cc is D -1/2=. For given morphologythe critical sheer yield strength and Hall-Petch slope K are constant . The critical phenomenon of the martensitic morphological variation is indicated by and K.The reliability of this mpdel is cpnfirmed Preliminarily by experiment,These values sc and K of the various morphologies are measured. The analytic result of the values K for various morphologies shows, (111)r and (225)r morphologicl martensites are source dislocation neucleating model at grain boundary. The modulus of Burgers Vector of (111), martesitic source dislocation equals only half modulus of Burgers Vector of (225)r martensitic source dislocation. The modulus of Burgers Vector of cryptocrystalline martensitic source dislocation is between the moduli of Burgers Vector of (111)r and (225)Y martensitic source dislocation. The 'cryptocrystalline' martensite neucleation is not only containing source dislocation model at gvein boundary, but also containing' partial soft model neucleation'which causes increasing neucleating density markedly, thus 'cryptocrystalline' martensite is formed.
出处
《上海第二工业大学学报》
1990年第1期23-29,共7页
Journal of Shanghai Polytechnic University
