摘要
针对某飞机铸造镁合金件螺栓孔开裂失效的问题,通过化学成分分析、断口宏观观察和微观形貌观察、显微组织分析和硬度测试等方法,并结合有限元应力分析和强度校核等对裂纹产生的原因进行了分析。结果表明,由于铸造缩松和人工加工破坏了氧化膜,使得暴露的镁基体与附着冷凝水发生电化学反应形成早期微裂纹,此外铸造镁合金中铝元素的过量添加造成晶界处偏析物过多,从而降低了晶界结合力,使裂纹扩展阻力降低,在残留应力的长期作用下,微裂纹不断扩展造成最终的应力腐蚀裂纹。
To study the cracking failure of casting magnesium bolt hole, composition analysis, macroscopic analysis and microscopic analysis, microstructure analysis and hardness testing and finite element analysis were used to explore the characters of cracking. The results show that exposed magnesium formed electrochemical reaction with attached liquid to form microcracks due to the damage of oxide film because of casting loosening and processing. The addition of excess Al caused more grain boundary segregation and reduced grain boundary binding force under long-term residual loads, the micro cracks continued expanding and thus caused eventual stress corrosion cracking failure.
出处
《腐蚀与防护》
CAS
北大核心
2016年第2期171-174,共4页
Corrosion & Protection
关键词
铸造镁合金
铸造缩松
应力腐蚀裂纹
casting magnesium alloy
casting loosening
stress corrosion cracking
