摘要
目的为了解决火炮击针断裂的问题。方法对断裂的火炮击针进行了宏观检查、化学成分分析、机械性能测试、断口分析、宏微观组织检测,确定了击针断裂的性质和产生原因。结果火炮击针断口属多源疲劳断口。结论击针断裂的主要原因:一是螺纹槽根部半径R较小,截面过渡不够平滑和自然,形成了较大的应力集中;二是螺纹槽根部的加工比较粗糙,进一步加剧了应力集中;另外,发射药形成的高温气体对火炮击针螺纹槽根部有腐蚀作用,导致击针螺纹槽根部R处出现点蚀坑,点蚀坑破坏了该处的表面完整性,形成了较大的应力集中,导致在点蚀坑处萌生了早期疲劳裂纹。建议改进工艺设计,增大螺纹槽根部R,确保截面过渡平滑自然,以降低颈部的应力集中系数;改进加工能力和水平,防止出现机加工缺陷。
Objective To solve the problem of artillery pin crack. Methods The properties and causes of the artillery pin crack were determined by macroscopic examination, chemical component analysis, mechanical property testing, frac- ture analysis, and macro- and microscopic tissue examination. Results The artillery pin crack belonged to multi-resource cut off. Conclusion The causes for the artillery pin crack were as following： first, the cross-section transition was not smooth enough due to the small R at the basis of the thread groove, leading to concentration of stress ; second, the transition zone at the basis of the thread groove was not round and smooth enough, which further aggravate the concentration of stress, and finally, another cause was that the high-temperature propellant gas led to an erosion at the thread basis so that many e- rosion pits occurred. The pits damaged the surface completeness and caused stress concentration, hence the preliminary fatigue cracks formed on the erosive pits. It is suggested to improve the process design, increase the R at the basis of the thread groove, to ensure the smooth transition of the cross-section transition and reduce the stress concentration coefficient at the neck, and to improve the processing capacity and skills to avoid machine processing defects.
出处
《精密成形工程》
2014年第2期45-50,共6页
Journal of Netshape Forming Engineering
关键词
多源疲劳裂纹
应力集中
断裂
点蚀坑
fatigue fracture
stress concentration
crack
corrosion pit
作者简介
秦会常（1972-），男，山东泰安人，高级工程师，主要工作方向为金属材料检测及热处理技术。
