关键词: 活塞裙部；磨损失效；铸造铝；铁相夹杂；失效分析

Abstract: During the driving of an automobile engine, the user feedbacks that the engine jitter is serious and the noise is large. The engine was disassembled for inspection, and it was found that the piston skirt was seriously worn and the material fell off. In this paper, the failure piston is analyzed in detail from the aspects of macro inspection of piston wear parts, piston hardness, chemical composition and metallographic structure. It is found that the content of iron in the chemical composition of the piston exceeds the standard, and there are coarse fishbone and needle iron impurities in the alloy. The brittle and hard inclusions produce cracks under the stress of the piston under service conditions, and finally destabilize, expand and fall off, resulting in piston failure,to provide some reference for solving this type of problem.

Key words: Piston skirt; Wear failure; Cast aluminum; Iron inclusion; Failure analysis