退火处理对紫铜组织和机械性能影响的试验研究

EXPERIMENTAL RESEARCH ON THE EFFECT OF ANNEALED TREATMENT ON MICROSTRUCTRUE AND MECHANICAL PROPERTIES OF PURE COPPER

研究退火处理对紫铜组织及机械性能的影响,利用X射线衍射、金相观测、硬度测量、拉伸和疲劳试验以及扫描电子显微镜观测等试验手段,对比分析了退火前后紫铜的金相组织、基本力学性能、疲劳寿命、断口显微形貌和疲劳裂纹扩展行为等。考察了表面形貌对材料试件的疲劳寿命的影响,利用带缺口的试件对疲劳裂纹扩展行为进行了观测,给出了退火前后疲劳裂纹扩展速率及疲劳寿命随表面粗糙度增大而改变的定量结果。结果表明:退火后紫铜主要衍射峰出现窄化,其内部晶粒增大;材料屈服应力、弹性模量、维氏硬度及疲劳性能显著降低。试件疲劳寿命受表面粗糙度影响的敏感性在退火后降低。

The effects of annealed treatment on the microstructure and mechanical properties of pure copper were investigated by using X-ray diffraction（XRD）, optical microscopy, hardness test, tension and fatigue tests, and scanning electron microscope（SEM） methods. The effect of surface topography for fatigue life was studied. Observation of fatigue crack propagation was operated using notched specimens. The quantified results of crack growth rate and the relationship between roughness and fatigue life were obtained. The results show that the microstructure and mechanical properties changed after the annealing. Firstly, the diffraction peaks became narrow and the grains became larger. Secondly, the tensile strength, elasticity modulus, Vickers hardness（HV） and fatigue strength of annealed pure copper were significantly decreased. Lastly, the sensitivity of fatigue life on roughness became lower, and the fatigue crack initiated earlier and propagated faster.