Ti-V-Mo复合微合金钢中(Ti,V,Mo)C在γ/α中沉淀析出的动力学

Kinetics of(Ti,V,Mo)C Precipitated in γ/α Matrix of Ti-V-Mo Complex Microalloyed Steel

根据多元复合析出相的固溶析出理论和经典形核长大动力学理论,计算了Ti-V-Mo复合微合金钢中(Ti,V,Mo)C在奥氏体(γ)和铁素体(α)中沉淀析出的形核参量、析出-时间-温度(PTT)曲线、形核率-温度(Nr T)曲线,并探讨了奥氏体中形变储能和形变诱导析出量对(Ti,V,Mo)C在γ/α中沉淀析出动力学的影响。结果表明,复合析出相(Ti,V,Mo)C在γ/α中沉淀析出的PTT曲线呈典型的"C"曲线形状,而Nr T曲线表现为典型的反"C"曲线形状,(Ti,V,Mo)C在γ中的最快析出温度为1020~1050℃。增加γ的形变储能,使(Ti,V,Mo)C在γ中沉淀析出的PTT曲线向左上方移动。增加γ中(Ti,V,Mo)C沉淀析出的形变诱导析出量,使(Ti,V,Mo)C在α中沉淀析出的Nr T曲线向右下方移动,经计算可知,(Ti,V,Mo)C在α中的最大形核率温度在630~650℃,理论计算结果和实验结果吻合较好。

In recent years, in order to develop the higher strength steel, the idea of increasing the strength of the hot rolled ferritic steel via complex Ti microalloyed technology has been widely accepted and applied, such as Ti-Nb, Ti-Mo, Ti-Nb-Mo and Ti-V-Mo. It is important to know the thermodynamics and kinetics of complex Ti contained precipitates for controlling the precipitation behavior of carbides and improving the mechanical properties of complex Ti microalloyed steels. In this work, according to the classical nulceation and growth kinetics theory and the solubility products of various carbides in austenite/ferrite（γ/α） matrix, the precipitation-time-temperature（PTT） curve, nucleation-time（Nr T） curve and the nucleation parameters of（Ti, V, Mo）C carbides in γ/α matrix of Ti-V-Mo complex microalloyed steel were obtained through the theoretical calculation. Moreover, the effects of deformation stored energy and the amount of strain-induced precipitation in γ matrix on the precipitation kinetics of（Ti, V, Mo）C were discussed. The results showed that the PTT diagrams of（Ti, V, Mo）C in γ/α matrix showed ＂C＂ shape curve,while the Nr T curves showed inverse ＂C＂ shape curve. The nose temperature of（Ti, V, Mo）C in g matrix is about 1020~1050 ℃. Increasing the deformation stored energy of γ matrix moves the PPT curve to the upper left. In addition, the Nr T curve of（Ti, V, Mo）C precipitated in α matrix moves towards to the lower right by properly increasing the amount of strain-induced precipitation in γ matrix. The maximum nucleation rate temperature of（Ti, V, Mo）C in ferrite is around 630~650 ℃ from the theoretical calculation,which agrees well with the result of experimental observation.