粗晶奥氏体HTP钢中形变诱导析出的定量研究

QUANTITATIVE INVESTIGATION OF DEFORMATION INDUCED PRECIPITATION IN COARSE GRAINED AUSTENITE HTP STEEL

利用double-hit实验与场发射扫描电镜定量研究了低碳高铌钢(0.032%C-0.089%Nb,HTP钢)粗晶奥氏体(约800μm)中的形变诱导Nb(C,N)析出规律,结果表明,在1000—900℃温度区间变形时,随着形变温度的降低,析出开始(5%析出量)时间逐渐缩短,析出开始时间与温度关系曲线具有C曲线的特征.随着形变温度的降低,析出相颗粒密度逐渐增加而颗粒直径减小,析出动力学满足修正的Avrami方程,Avrami指数约为1.1.析出相主要在位错及位错结等位置优先形核,形成条带状或网状.拟合得到的模型能够预测奥氏体低碳高铌钢的析出开始时间及析出动力学.

Deformation-induced Nb（C, N） precipitate in a low-carbon （0.032%） high-Nb （0.089%） microalloyed steel （HTP steel） with coarse grained austenite was quantitatively analyzed by double-hit test and field emission microscopy. The results indicate that when deformed in a range of 1000-900℃ the precipitation-start time is shortened and the relationship of the time and temper- ature is a C-type curve. The number of Nb（C, N） particles increases while particle diameter decreases with decreasing deformation temperature. The precipitation kinetics obeys the modified Avrami equa- tion and the Avrami exponent is about 1.1. The precipitates nucleated preferentially at dislocations. A model was developed and can be used to predict the precipitation-start time and precipitation kinetics.