在500℃采用C方式ECAP变形制备了亚微晶45钢, 用光学显微镜(OM)、透射电子显微镜(TEM)和电子衍射(SAED)等分析技术对其进行表征, 研究了铁素体组织的演变特征和晶粒细化机制。结果表明: 在初始变形道次后, 原始的粗大铁素体晶粒因剧烈剪切变形而沿着剪切变形的方向形成剪切变形带, 在其内大量的具有亚微米尺寸的板条状位错胞或亚晶使铁素体晶粒显著细化。进一步变形使板条状位错胞或亚晶组织继续细化, 但不明显。随着ECAP变形道次的增加, 以晶界滑移和晶粒转动的方式最终获得等轴状且具有大角度晶界分离的亚微晶组织。
A submicrometer grain 45C steel was fabricated by equal channel angular pressing (ECAP) by C way at 500oC and was characterized by optical microscope (OM), transmission electron microscopy (TEM) and selected area electron diffraction (SAED) technique. The microstructural development and grain refinement of ferrite was investigated. The results show that, at the first pass of ECAP, the original coarse ferrite grains were broke up into the parallel shear bands of elongated dislocation cells and even subgrains with submicrometer size along the shear direction, resulting from bigger shear deformation. Further pressings results in a slight decrease in the size of elongated dislocation cells and subgrains. With ECAP passes increasing, equiaxed ultrafined ferrite grains with high-angle boundaries were achieved by grains sliding and rotation.
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