65Mn卡箍氢脆断裂失效分析

Failure analysis of 65Mn clamp hydrogen embrittlement

厚度0.5 mm飞机座舱照明用65Mn卡箍装配过程中出现裂纹,扳动后断裂。采用能谱分析、扫描电镜等对断口处进行分析,结果表明:卡箍断裂件化学成分符合标准;断口大多为沿晶断裂,晶界面上有发纹线,未发现二次裂纹,部分断裂为穿晶断裂,未发现断口边缘有加工损伤痕迹;能谱分析未在晶界上发现杂质元素;金相组织为回火索氏体;显微硬度符合标准要求。卡箍产生断裂的主要原因:由于壁厚太薄,拐角较锐利,镀锌时致使大量氢聚集并呈弥散分布,进而形成沿晶裂纹,在外力作用下,导致沿晶脆性断裂。

Thickness 0. 5 mm 65 Mn clamp for aircraft cockpit lighting appears crack in the process of assembly using,fractures after pulling. The fracture was analyzed by adopting energy spectrum analysis（ EDS） and scanning electron microscopy（ SEM）,results show that： chemical composition of clamp fracture meets standard. The fracture is intergranular fracture morphology,grain boundary surface appears capilary crack,not find secondary crack,part grain is transgranular fracture,there is no processing damage at fracture edge. There is no impurity element at grain boundary with EDS analysis. Microstructure is tempered sorbite. Micro-hardness meets requirement of standard. The main cause of clamp fracture is： too thin wall thickness and the sharp corner of clamp,a large amount of hydrogen accumulation and dispersion distribution form in zinc plating,then intergranular crack forms,the intergranular brittle fracture takes place under the action of external force.