稀土重轨钢的静态再结晶研究

Static Recrystallization of Rare Earth Heavy Rails

通过Gleeble-1500D型热模拟机对REⅡ稀土重轨钢进行应变速率为5 s-1、变形量均为25%的双道次热压缩模拟试验,分别测定820,850,880,1000℃下的真应力-真应变曲线,采用后插法计算奥氏体等温变形后道次间隙时间1～1200 s内的软化率,研究REⅡ稀土重轨钢的静态再结晶规律。结果显示:当变形温度为>1000℃时,REⅡ重轨钢完成静态再结晶弛豫时间<90 s;当变形温度<820℃时,静态再结晶很难进行,即使弛豫时间延长至1000 s,再结晶百分数也只有38.8%;当变形温度为850和880℃时,再结晶过程会出现析出现象,对抑制静态再结晶的进行有影响,导致软化率曲线上出现了平台。

The true stress-strain curves of REⅡheavy rails at 820,850,880 and 1100 ℃ were measured respectively by double-pass compression tests on Gleeble-1500D with strain rate of 5 s-1 and deformation of 25%.The rear differential method was used for calculating the softening rate within interval of passes,which was from 1 to 1200 s after isothermal deformation and the law of static recrystallization was studied for providing experimental and theoretical basis to optimize the rolling process.The results indicated that the relaxation time for performing recrystallization is 90 s as deformation temperature 1000 ℃,and as deformation temperature820 ℃,the static recrystallizing fraction was only 38.8% even extending relaxation time to 1000 s which showed the difficulty of occurring recrystallization.Because precipitation induced by deformation inhibited the static recrystallization,the platform appeared at the softening curve of 850 and 880 ℃.