摘要
在不同脉冲电流条件下对模具钢P20进行电火花成形加工,研究了脉冲电流对试样表层的微观组织结构的影响,以及微观组织结构对表面性能的影响。结果表明,电火花成形加工后试样的表面分为烧蚀层、熔化凝固层和热影响层。随着脉冲电流的增大,熔化凝固层和热影响层的厚度增大;在加工过程中元素的扩散和迁移使熔化凝固层外侧碳元素和氧元素的浓度较高。电火花成形加工过程相当于热处理过程,从熔化凝固层到热影响层、基体,显微硬度快速降低。有限元模拟计算表明,在熔化凝固层内的垂直与界面微裂纹主要是加工放热过程中的残余应力引起的。
The P20 specimens were machined with different electrical discharging currents to investi- gate the effect of the pulse current on the micro structure and properties of the specimen surface. There are three layers on the specimen surface： ablation layer, molten layer and recrystallized layer. The thick- ness of the molten layer and recrystallized layer increases with the increment of the pulse current. The content of the oxygen and carbon element on the outside of the molten layer is higher than that in the base metal for the element diffuse during the machining. The micro hardness reduces from the out layer to the base metal for the heat treatment during the discharge machining. Micro fracture is found in the molten layer which is caused by the residual stress during the machining according the finite element analysis.
出处
《材料研究学报》
EI
CAS
CSCD
北大核心
2013年第5期449-453,共5页
Chinese Journal of Materials Research
基金
国家重点基础研究发展计划2011CB610506
北京市教育委员会科研计划KM201310853006资助项目~~
关键词
金属材料
模具钢
电火花成形
脉冲电流
显微硬度
残余应力
metallic materials, die steel, electrical discharge machining, pulse current, micro hard- ness, residual stress
