Abstract: 150~350 nm super finc grain structure of φ8 mm round stainless steel 00Cr19Ni10-0.025C,18.75Cr, 10.96Ni has been obtained by 8 pass equal channel angular pressing(ECAP)with extrusion speed 9 mm/s at 700 ℃.The  structure evolution of steel in ECAP was analyzed by optical microscope,scanning and transmission electron microscope and X-ray diffraction method. The grain refinement mechanism - dislocation,twins and dynamic recrystallization is proposed and the research discovers that the twins is main grain refining mechanism in 1～4 pass and the dynamic recrystallization is main refining mechanism in 5~8 pass.

摘要： φ8 mm 00Cr19Ni10不锈钢(%:0.025C、18.75Cr、10.96Ni)经700℃、挤压速度9mm/s、8道次等通道 挤压后获得150~350nm 超细晶组织。通过光学显微镜，扫描和透射电镜，X-射线衍射，分析了在等通道挤压变形 过程钢的微观组织演变，提出晶粒细化的位错、孪晶和动态再结晶机制，研究发现在1～4道次以孪晶细化机制为 主，5～8道次以动态再结晶细化机制为主。

关键词: 等通道热挤压法, 奥氏体不锈钢, 晶粒细化机理