Thermodynamic Study on Structure Designing of Microalloyed Steel.

关于微合金钢中相位均衡的热动力学研究已经被携带出来，随后的结果已经获得：1。Fe-C-Ti、Fe-C-Nb和Fe-C-V系统中的均衡相位：奥氏体TiC、NbC和VC的溶解度是通过扩散双方法测量的。这一点被证实是，高碳区域的易失性大于低碳区域的易失性，因为低碳区域的Ti、Nb和V在奥地利的活性。在这一事实的含义中，在这些系统中，奥斯汀的相位边界在垂直部分展示了特征形状。Fe-C-Nb-V系统中NbC和VC之间的不安全性差距是通过对Fe-C-Nb-V样品中碳化物提取的晶格参数测量来确定的。这是对该漏洞的调查，其危险性差距与1500摄氏度左右的临界温度几乎是对称的。在奥地利，VC的可溶性的腐蚀元素的影响使Cr、Mo、W和Mn增加了VC在奥地利的可溶性，同时Si、Al、Ni和Co decrease。这些事实很好地说明了在奥地利，依赖元素和碳之间的相互作用。Phase Equilibria in the Fe-C-B System Phase equilibria in the Fe-Rich portion of the Fe-C-B system were analyzed on the basis of thermodynamic calculations of the Fe-C and Fe-B systems。The effects of B on the Austenite field， the Liquidus and solidus tcmperatures and the stability of Fe@>D23@>D2C and Fe@>D223@>D2C_6 carbides were calculated。

Thermodynamic study on phase equilibria in microalloyed steels has been carried out and the following results were obtained:1. Phase Equilibria in the Fe-C-Ti, Fe-C-Nb and Fe-C-V Systems The solubility of TiC, NbC and VC in austenite was measured by diffusion couple method. It was confirmed that the solubility in high carbon region is larger than that in low carbon region due to the lowering of the activity of Ti, Nb and V by carbon in austenite. In consequence of this fact, the phase boundaries of austenite in these systems exhibite a characteristic shape in the vertical sections.2. Miscibility Gap between NbC and VC in the Fe-C-Nb-V System The miscibility gap between NbC and VC was determined by lattice parameter measurements on carbides extraction from the Fe-C-Nb-V specimens. It was examined that the miscibility gap was almost symmetric with the critical temperature of about 1500゜C.3. Effect of Alloying elements on the Solubility of VC in Austenite It was ascertained that Cr, Mo, W and Mn increase the solubility of VC in austenite, while Si, Al, Ni and Co decrease it. These facts were well explained by considering the interactions between alloying elements and carbon in austenite.4. Phase Equilibria in the Fe-C-B System Phase equilibria in the Fe-rich portion of the Fe-C-B system were analyzed on the basis of thermodynamic calculations of the Fe-C and Fe-B systems. The effects of B on the austenite field, the liquidus and solidus tcmperatures and the stability of Fe@>D23@>D2C and Fe@>D223@>D2C_6 carbides were calculated.