Ti-IF钢铁素体变形动态再结晶临界应变模型

用Thermecmaster-Z热模拟试验机试验得出成分为0.006 7%C-0.045 0%Ti的Ti-IF(无间隙原子)钢在变形温度750~900℃和变形速率0.1~40 s^-1时的应力-应变曲线,确定了Zener-Holloman参数Z与应变速率.ε和温度T(K)的关系式Z=.εexp(39 507/T),并建立了临界应变εc与原始晶粒尺寸d0和Z参数的临界应变方程ε_c=2.314 4×10^-3×d^{-0.8003 9}×Z^0.050。结果表明,在相同变形速率下,850℃变形时动态再结晶最易发生,当变形温度提高至900℃(两相区)时,即使在低变形速率(1 s^-1),也不发生动态再结晶。当变形速率大于1 s^-1时,Ti-IF钢热加工时不能出现动态再结晶。临界应变预测值与实测值比较,平均误差≤5%。

Model of Dynamic Recrystallization Critical Strain in Ferrite Deformation of Ti-IF Steel

Hie stress-strain curves of 0.006 7C-0.045 0Ti Ti-IF (interstitial free) steel with deformation temperature 750 - 900 °C and deformation rate 0.1 - 40^-1 has been tested and obtained  Ihennecmaster-Z thermal simulation test machine, based on that the relational expression between Zener-Holloman parameter Z and deformation rate ε - temperature T (K) ： Z= e exp (39 507/T) is defined, and the critical strain fonnula for relation between critical strain ec and original grain size Z parameter： e_c = 2.314 4 x 10^-3 X d^{-0.8003 9}×Z^0.050 is established. The results showed that with same deformation rate the dynamic recrystallization of steel occurred most easily at 850 ℃, as deformation temperature increased to 900 °C (dual phase region) , the dynamic recrystallization un-occurred even at low deformation rate (1 s^-1 ) , and as deformation rate was more than 10 s^-1, the dynamic recrystallization of Ti-IF steel also un-occurred during hot rolling. With comparison between predicted value of critical strain and measured value, the average error was no more than 5 % .