身管内膛复合镀铬层的组织退化特征  

Degradation of microstructure of duplex electroplated chromium layers in gun barrels

作　　者：李怀学[1] 陈光南[1] 张坤[1] 罗耕星[1] 叶智军[1] 张建军 

机构地区：[1]中国科学院力学研究所表面改性实验室 [2]潍坊市质量技术监督局,山东潍坊261031

出　　处：《材料热处理学报》2007年第4期111-115,共5页Transactions of Materials and Heat Treatment

基　　金：国家自然科学基金(50471087);国家自然科学重点基金(50531060)

摘　　要：研究了某型号身管后膛射击后复合镀铬层(由顶层的高收缩性铬和底层的低收缩性铬组成)的组织及显微硬度退化特征。结果显示:经3000发射击后,复合镀铬层沿着涂层厚度方向呈现梯度性再结晶,其组织由射击前的柱状晶粒团簇逐渐转变成等轴晶粒团簇,这导致镀铬层的硬度梯度分布;高收缩性铬层的表层晶粒成长最大,其相应的硬度由初始的960HV左右急剧下降到330HV左右。另外,高收缩性铬层许多短小的镶嵌微裂纹消失,而且一些穿透镀铬层的主裂纹形成并扩展到基体。根据服役条件下镀铬层的组织及性能退化特征,调整优化镀铬层的组织或许能有效地延长身管内膛镀铬层的寿命。The microstructure and hardness of duplex electrodeposited chromium layers （consisting of high-contract （HC） and low-contract （LC） chromium layer） in gun barrels before and after firing were investigated. The results show that re-crystallization of the electrodeposited chromium layer occurs in a manner of gradient in the coating thickness direction after firing 3000 rounds. Moreover, the columnar grain clusters of chromium coatings before firing gradually becomes equal-axis grains along the thickness direction, which results in the gradient distribution of hardness. While the crystal clusters at the top of HC chromium layer grows largest and its hardness valuation sharply drops from about 960HV to 330HV. In addition, after firing, many shorter micro-cracks embedded in the HC chromium disappeared and the main cracks throughout the whole electrodeposited layers form and extend into the underlying substrate. The service-life of chromium coatings in gun barrels may be effectively improved by modifying and optimizing the microstructure of as-deposited chromium layers, according to the degradation characterization of the microstructure and property of chromium coatings under the operating service conditions.

关 键 词：身管 复合镀铬层 退化 再结晶 微裂纹 

分 类 号：TG174.44[金属学及工艺—金属表面处理]