低碳钢在形变作用下产生的超平衡数量铁素体

Strain Induced Over-Equilibrium Ferrite Fraction in Low Carbon Steel

试验研究了低碳钢变形后经历等温及随后快冷的组织转变,发现在Ae3附近及以下一定温度范围内大变形会使室温组织中出现超平衡数量的铁素体。形变后等温,出现超平衡数量铁素体向奥氏体的逆相变,该弛豫过程具有类似C曲线的动力学特征;而且经过等温后,伴随着铁素体数量的减少存在其晶粒尺寸增大的现象。随着变形温度的降低,超平衡数量铁素体在数量以及晶粒尺寸上的稳定性均提高。

The microstructure evolutions during isothermal holding combined with subsequently accelerated cooling were investigated in deformed low carbon steel. It is found that over-equilibrium ferrite volume fraction would exist at room temperature after heavy deformation at different temperatures near-by Ae3. Reverse transformation from letrite to austenite would occur during isothermal holding. This relaxation phenomenon has a dynamic characteristic which is similar to C curve. Further, ferrite grain size would grow combined with the ferrite volume fraction decrease during isothermal boding. But the stability of over-equilibrium ferrite, no matter on volume fraction or on grain size, would increase with the deformation temperature drop.