微合金钢初始凝固中奥氏体开始长大的温度  

Investigations on the Temperature for Completion of Austenite Transformation During the Initial Solidification Process of Micro-alloy Steels

作　　者：刘江[1] 文光华[1] 唐萍[1] 李云峰[1] 

机构地区：[1]重庆大学材料科学与工程学院,重庆沙坪坝400044

出　　处：《东北大学学报（自然科学版）》2014年第3期370-374,共5页Journal of Northeastern University(Natural Science)

基　　金：国家自然科学基金资助项目(51174242)

摘　　要：通过共聚焦激光显微镜对P510L钢的初始凝固过程进行了原位动态观察以考察δ相生成、包晶反应以及γ相的形成过程,并探索奥氏体开始长大温度.研究结果表明:1)冷却速度为2.5℃/s时P510L钢的冷却模式为首先从液相中析出δ铁素体,然后在液相与δ铁素体相之间发生包晶反应(L+δ→γ),进入三相共存区,液相消失后剩余的δ相通过固态扩散转变为γ相;2)在初始凝固过程中,奥氏体先进行一部分吞并、长大,然后才实现过剩δ铁素体向奥氏体的同素异构转变,最后实现完全奥氏体化;3)通过原位动态观察,探索了一种较为准确的确定原始奥氏体开始长大温度的实验方法,提高了奥氏体晶粒预测模型的准确性.Coarse austenite grain formed in the initial solidification process is an important factor to affect the transverse cracking of medium carbon micro-alloyed steels. The initial solidification process of PS10L steels were observed by the confocal laser scanning microscope in order to inspect the formation of 8 and γ phases and the peritectic reaction, and explore the temperature for the completion of γtransformation. The results showed that： 1 ） With the cooling rate of 2.5 ℃/s, the cooling mode of PS10L steel was that 8-ferrite precipitated from the liquid phase first, then the peritectic reaction （ L ＋ δ→γ） occured between the 8-ferrite phase and the liquid phase, then they entered to the three-phase coexistence region. With the liquid phase disappeared, the remain 8 phase transformed into γ phase by the solid state diffusion;2） In the initial solidification process, parts of the austenite grains annexed and grew up first, then the remain δ-ferrite transformed into austenite with the allotropic heterogeneous, and the fully austenite region achieved at last; 3 ） A more accurate method about determining the temperature for the completion of γ transformation was sought by in-situ dynamic observation, and the accuracy of a model for predicting the austenite grain size was thus improved.

关 键 词：粗大奥氏体 原位观察 初始凝固 奥氏体开始长大温度 奥氏体晶粒预测模型 

分 类 号：TG777.1[金属学及工艺—刀具与模具]