等通道角挤压变形中高碳珠光体钢的组织演变

Microstructure evolution in a pearlitic structured high carbon steel during equal channel angular pressing

在650℃对原始组织为层片状珠光体的T8钢进行Bc路径的多道次等通道角挤压(ECAP)变形,借助SEM、TEM和AFM研究了变形过程中渗碳体片层的演变情况。结果表明:渗碳体片层表现出强烈的塑性变形能力,主要以剪切断裂、扭折、弯曲等变形方式来适应剧烈的塑性变形;四道次温变形后得到晶粒尺度均在亚微米量级的超微细复相组织(α+θ);球化完全的渗碳体颗粒粒径呈双峰分布,从三维的角度表征渗碳体的组织演变及其特性与从二维角度观察分析的结果相吻合。

A T8 steel with a fully pearlitic structure was studied by equal channel angular pressing （ECAP） via route Bc at 650 ℃. The microstructure evolution of the cementite lamellae after processing was analyzed by SEM,TEM and atomic force microscopy. The results show that the cementite in the pearlite has higher plastic deformation capability. The severe shear deformation of ECAP is accommodated by bending, shearing and shearing fracture etc in the pearlite lamellae. After four passes, an uhrafine microduplex structure （ferrite ＋ cementite） with a grain size at the sub-micrometer level is observed. The cementite particle size distribution is bimodal. The microstructure evolution of the cementite lamellae is observed in three dimensions and is consistent with the results observed in two dimensions.