热轧工艺对厚板板厚方向组织和力学性能均匀性的影响

Effect of hot rolling process on uniformity of microstructure and mechanical properties of thick plate in thickness direction

采用光学显微镜(OM)、透射电镜(TEM)及有限元分析(FEA)等研究了轧制工艺对Fe-0.2C-1.45Mn-Nb-V-Ti钢板厚方向的组织和力学性能均匀性的影响。结果表明:在压缩比受限的条件下,利用奥氏体晶界促进形核的机制(即边界诱导相变机制,BIT机制)可以达到细化晶粒的目的,试验钢的平均晶粒尺寸均小于10μm;结合温度与累计应变的反向分布特点和轧制工艺的优化,轧制63 mm厚的试样表面和中心晶粒尺寸偏差小于2μm,有效改善了晶粒尺寸沿板厚方向的偏差。在本文的轧制工艺下,提高了厚板沿厚度方向的组织均匀性,获得了优异的力学性能。

Effect of rolling process on uniformity of microstructure and mechanical properties in the thickness direction of Fe-0.2C-1.45Mn-Nb-V-Ti steel plate was studied by means of optical microscope(OM),transmission electron microscopy(TEM)and finite element analysis(FEA).The results show that under the condition of limited compression ratio,the grain refinement can be achieved by using the mechanism of austenite grain boundary promoting nucleation(i.e.boundary induced transformation mechanism,BIT mechanism),and the average grain size of the experimental steel is less than 10μm.Combined with the reverse distribution characteristics of temperature and cumulative strain as well as the optimization of rolling process,the deviation of grain size between the surface and the center of the rolled 63 mm sample is less than 2μm,and the deviation of the grain size along the thickness direction is effectively improved.Under the proposed rolling process,the microstructure uniformity of the thick plate along the thickness direction is improved,and excellent mechanical properties are obtained.