共析钢经表面研磨处理后微观组织的演化

The Microstructure Evolution of Eutectoid Steel Subjected to Surface Mechanical Attrition

利用表面研磨处理(SMAT)在共析钢上制备出具有纳米晶体结构的表面层,并利用X射线衍射和透射电镜分析了纳米表面层的微观组织结构及其演变.结果表明:原始组织为层片状铁素体+渗碳体两相复合组织的共析钢经过SMAT后,铁素体晶粒由于位错产生、位错缠结形成位错胞,然后分割晶粒使铁素体细化至纳米尺度,而渗碳体在强烈塑性变形下,经历弯曲、断裂,最终分解成体心立方铁素体和底心正交的石墨.

A nanostructural surface layer was synthesized on a eutectoid steel by surface mechanical attrition(SMAT) treatment and its microstructure and evolution were characterized by means of X-ray and TEM.The result reveales that the original structure of pearlite consists of alternate thin plates of ferrite and cementite.After subjected to SMAT treatment,the ferrite grain size is reduced to nanometer scale because of dislocation activities: dislocations tangled,dislocation cells formed and finally led to division of ferrite grains;while the cementite lath underwent bending,fracture and finally dissolved into body-centered cubic ferrite and end-centered orthorhombic graphite under the condition of severe plastic deformation.