低碳结构钢的奥氏体晶粒超细化

Ultra-Refinement of Austenitic Grains in Low-Carbon Structural Steel

以两种不同成分的低碳微合金结构钢为研究对象,结合热模拟实验与实验室热轧实验,研究原始组织、化学成分及部分加热条件对低碳钢加热过程奥氏体晶粒超细化的影响规律.结果表明,以热轧态铁素体/珠光体经温轧并且冷变形的组织为原始组织最有利于获得超细晶奥氏体(1μm);此外适量添加合金元素Nb,Ti,V,适当提高加热速度均有利于细化奥氏体,而当加热速度大于100℃/s时,对奥氏体的超细化效果不明显;另外,加热前预变形可以显著细化奥氏体晶粒,且提高其尺寸均匀性.

Two low-carbon alloyed structural steel of different compositions were investigated via hot-rolling tests and thermal simulation tests for the effects of their chemical compositions, original microstructures and partial heating process on the ultra-fine austenitic grains. The results indicated that the process of warm rolling and cold deformation is most beneficial to enabling the ferritic/pearlitic structure being hot-rolled as original one to obtain ultra-fine austenite with grain size about 1μm. Moreover, adding properly the alloying elements Nb, V and Ti and increasing heating rate can also be helpful to austenitic grain refining, and the ultra-refining effect is not obvious if the heating rate is more than 100 ℃/s. But, the austenitic grain refining is obvious with homogeneous grain size if the steel is predeformed before heating.