ZrC/奥氏体相界面形变诱导铁素体相变超细化机理

Mechanism of Ultrafine Grain of Deformation Induced Ferrite Transformation at ZrC/Austenitic Interface

利用Gleeble-1500热模拟试验机进行单轴热压缩实验,研究了含ZrC粒子的低碳钢在形变诱导相变过程中ZrC粒子对铁素体晶粒细化的影响及铁素体形核的基本特性。结果表明:一定粒径和体积分数的ZrC粒子弥散分布于基体相中时,能够阻碍位错的运动,形成集中形变区,加速形变诱导相变的进程,因而提高铁素体形核率,导致铁素体晶粒细化;ZrC/奥氏体相界面上形变诱导铁素体相变具有形核位置不饱和性、新生α相超细晶的特点;在应变条件下,铁素体晶粒在〈111〉方向择优取向,晶粒内部存在一定量的小角度晶界,由于铁素体动态再结晶的发生,组织进一步细化。ZrC/奥氏体相界面铁素体晶粒的超细化机理是形变诱导相变、铁素体动态再结晶及ZrC粒子弥散强化三者同时作用的结果。

In order to deeply understand the mechanism of ultrafine grain of the low carbon steel obtaining ZrC particles,the effects of ZrC particles on ferrite grain refinement and basic characteristics of ferrite nucleating for this steel after deformation induced ferrite transformation at ZrC/austenitic interface were investigated by uniaxial hot compression simulation experiment.The results show that ZrC particles with definite size and suitable volume fraction dispersing in the matrix phase can hinder the movement of dislocation,form concentrated deformation zone and speed up the process of deformation induced ferrite transformation,thus increasing the nucleation rate of ferrite,resulting in ultrafine grain.The deformation induced ferrite transformation at ZrC/austenitic interface has shaped the unsaturated nature of nuclear position and the new α-phase has the characteristics of ultra-fine grain.In the strain conditions,the ferrite grains in the direction of 〈111〉 preferred orientation,a certain amount of small angle grain boundaries exist within ferrite grains,as the occurrence of ferrite dynamic recrystallization,ferrite further refinement,so the micro-mechanism of the testing steel is results of the role of the three,including the deformation induced ferrite transformation,ferrite dynamic recrystallization and dispersion strengthening of ZrC particle at the same time.