摘要
某液压缸盖紧固用螺钉在进行试验时发生断裂。采用外观检查、断口宏微观观察、金相检验和硬度测试等方法对两枚断裂失效螺钉进行了分析。结果表明,螺钉A失效性质为过载断裂,其断裂原因主要与装配时拧紧力过大从而产生了扭转剪切开裂损伤有关;螺钉B失效性质为疲劳断裂,其断裂原因主要与螺钉B表面存在脱碳层导致疲劳强度大幅降低有关,且在装配时发生倾斜,螺钉一侧存在附加拉应力,对疲劳失效也有一定的促进作用。建议严格控制热处理工艺和装配过程力矩大小,并加强螺钉孔和螺钉的加工精度控制。
Two fastening screws of fluid pressure cylinder head were fractured during test running. The feature and failure cause of the screws were analyzed by fracture observation, metallographic examination and hardness test. The results show that the fracture mode of the serew A was overload breakage which was relevant to the overloading assembly stress and led to torsion shear cracking; The screw B was fatigue failure because of the decarburized layer and the additional tensile stress in the assembly process which accelerated fatigue failure. It is proposed that the heat treatment process and the assembly stress should be controlled strictly.
出处
《金属热处理》
CAS
CSCD
北大核心
2014年第2期141-144,共4页
Heat Treatment of Metals
基金
中航工业航材院益材青年基金(YF53110738)
关键词
螺钉
过载断裂
疲劳断裂
脱碳层
装配应力
screw
overload breakage
fatigue failure
decarburized layer
assembly stress
