Failure analysis of connecting rod fracture for a marine diesel engine
To solve the fracture of connecting rod in a certain marine diesel engine,the cause of connecting rod failure is determined through macroscopic fracture analysis,microscopic fracture analysis,metallographic structure and non-metallic inclusion analysis,chemical composition and mechanical performance analysis,some Improvement are also introduced and verified.The analysis results show that rough machining at the root of the connecting rod thread causes stress concentration,and there are many non-metallic inclusions in the connecting rod,with strip segregation at a certain angle to the root of the thread.This leads to non-metallic inclusions exposing at the root of the thread,exacerbating stress concentration,and generating cracks and expanding under the action of alternating forces,causing the connecting rod to fracture.After taking improvement measures such as reducing the content of non-metallic inclusions in connecting rods,changing the forging process of connecting rods,and improving the machining quality of connecting rod bolt holes,the actual machine operation verification are carried out approximately 4000 hours,and no connecting rod fracture fault occurres again.
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