304奥氏体不锈钢凝固相转变规律曲线（SPT曲线）建立

摘要

The Self⁃designed experimental apparatus which is employed to determine the phase transition of high temperature solidification, the high temperature solidification phase change process of 304 austenitic stainless steel at the different cooling rate was studied , and the phase⁃transition temperature from liquid phase (L) to the high temperature ferrite (δ) then to austenite phase (γ) was obtained, In addition, the solidification law of the high temperature phase transition on 304 austenitic stainless steel at different cooling rate was analysed,then the phase transition law curve of high temperature solidification—SPT curve was established. Results show that quenched the samples by the low⁃temperature Liquid nitrogen alcohol can keep the morphology of each phase at high temperature effectively. In this way, We can get the Component proportion and the variation of Component proportion among different phase composition at different cooling rate and different quenching temperature. Furthermore, we can get the Solidus、liquidus temperature and the phase inversion temperature of 304 austenitic stainless steel which help us establish the phase transition law curve(SPT).The results show that the increase of cooling rate can lead to a series of changes,such as,the phase transition mode will change, the phase diagram can move to the left, the temperature interval of phase reaction decreases.%利用自行设计的高温凝固相转变测定实验装置，研究了304奥氏体不锈钢在不同冷却速度下的高温凝固相转变过程，得到了凝固过程中液相（ L）到高温铁素体（δ）到奥氏体（γ）的相变温度。在此基础上分析了304奥氏体不锈钢在不同冷却速度下的高温凝固相转变规律，从而建立了304奥氏体不锈钢的低冷速凝固相转变规律曲线—SPT（Solidification phase transforma⁃tion）曲线。结果表明：对试样进行液氮酒精淬火有效地保留了试样高温时各相的状态。可以清楚的显示在不同冷速下的不同温度淬火时液相和固相的各相成份比例及在不同淬火温度下各成份体积比例的变化。通过研究体积比例变化，可以得到304奥氏体不锈钢在不同冷速下的液相线、固相线及各种反应开始和结束的转变温度（即SPT曲线）。由SPT曲线也可以看出，随着冷却速度的增大，相转变模式会发生变化，相图会向左移动，各相变反应的温度区间减小。