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详细描述了通过等通道转角挤压(ECAP)+临界区退火处理生产超细晶铁素体／马氏体双相(UFGF／MDP)钢的过程。本研究的目的,除了在应变梯度塑性原理中引入对增强应变硬化性产生影响的从几何学角度考虑必然会产生的高密度位错的理念外,还在于生产具有广泛应变硬化性(其它UFG材料几乎不具备)和超高强度及良好均匀延伸的UFGF／MDP钢。通过选择最佳的ECAP工艺路线以及临界区退火处理条件,能够生产出孤立的岛状UFG马氏体均匀地埋入UFG铁素体基体中的UFGF／MDP钢。根据ECAP过程中显微组织的变化探讨了在本研究的加工条件下这种独特显微组织的形成过程。UFGF／MDP钢的室温拉伸性能均优于粗晶对应钢种。更重要的是,尽管为UFG组织,但与其它UFG材料不同,本研究的UFGF／MDP钢从塑性变形开始就显现出广泛的应变硬化性,而这与晶粒尺寸无关,与应变梯度塑性有关。
The process of producing ultrafine-grained ferrite / martensite duplex (UFGF / MDP) steel by ECAP + critical zone annealing is described in detail. In addition to the concept of high-density dislocation, which is bound to be generated from the geometric point of view, in the strain-gradient-plasticity principle that has an effect on the strain hardening effect, the present study also aims to produce a material with a wide range of strain-hardening properties (other UFG materials Almost not available) and UFGF / MDP steels with ultra-high strength and good uniform elongation. By selecting the best ECAP process route and the critical zone annealing conditions, UFGF / MDP steels with isolated island-like UFG martensite in UFG ferrite matrix can be produced. The formation of this unique microstructure under the processing conditions of this study was explored on the basis of changes in microstructure during ECAP. UFGF / MDP steel tensile properties at room temperature are better than the corresponding coarse grain steel. More importantly, UFGF / MDP steels showed a wide range of strain hardening beginning with plastic deformation, in spite of being UFG-organized, in contrast to other UFG materials, regardless of grain size and related to strain gradient plasticity .