层错能在剧烈剪切变形时对晶粒细化的影响  

Influence of Stacking Fault Energy on Grain-refining during Severe Shear Deforming

作　　者：汪建敏[1] 周孔亢[2] 陆晋[3] 许晓静[4] 姜银方[4] 

机构地区：[1]江苏大学材料科学与工程学院,镇江212013 [2]江苏大学汽车与交通工程学院,镇江212013 [3]江苏大学电气信息工程学院,镇江212013 [4]江苏大学机械工程学院,镇江212013

出　　处：《机械工程学报》2008年第11期126-131,共6页Journal of Mechanical Engineering

摘　　要：基于等通道角挤压晶粒细化技术,研究不同材料在相同工艺条件下为什么其晶粒演化过程会出现较大的差异,提出晶体结构与层错能在等通道角挤压过程中的剧烈剪切变形对纳米/超细晶粒组织塑性变形及晶粒细化机制的影响。试验采用中低层错能的面心立方晶格纯铜和中高层错能的体心立方晶格中碳钢作为试验材料,挤压工艺采用冷挤压和Bc工艺路径。试验结果表明,中高层错能的体心立方晶格金属是以交滑移和位错分割方式使晶粒细化:中低层错能的面心立方晶格金属是以位错分割和孪生方式使晶粒细化。金属层错能越高,剧烈剪切变形时交滑移作用越大,晶粒细化的速度也越快。体心立方结构的钢在等通道角挤压四道次后可获得均匀的纳米/超细晶粒组织,而面心立方结构的铜挤压八道次后才可获得均匀的超细晶粒组织。Based on the equal channel angular pressing（ECAP）, why there is considerable difference between different metals in evolution of fine grained microstructure under same process conditions is investigated. Influences of lattice structures and stacking fault energy（SFE） on the mechanism of grain refinement and ultra-fine or nano-structurexi grains plastic deformation are put forward in severe shear deformation during ECAP. Experiments are conduced on face-centered cubic lattice pure copper with medium-low SFE, and body-centered cubic lattice medium carbon steel with medium-high SFE. Room-temperature pressing process and route Bc are adopted. Experimental results indicate that in bcc metal with medium-high SFE the formation of ultra-fine and nano-structured grains are caused by dislocation slip and intercross slip and in fcc metal with medium-low SFE the formation of ultra-fine grains is caused by dislocation slip plus twinning during severe shear deformation in ECAP process. The higher the stacking fault energy of metal is, the greater the effect of intercross dislocation slip, the quicker the speed of grain-refining will be during severe shear deforming. The homogeneous high angle boundary ultra-fine grains can be achieved in the steel through four passes and in the copper through eight passes by ECAR.

关 键 词：等通道角挤压 晶粒细化 层错能 剧烈剪切变形 超细晶 

分 类 号：TG146.1[一般工业技术—材料科学与工程] TG376[金属学及工艺—金属材料]