一批柱塞套在磨削加工后发现其中有十几件出现裂纹。采用宏观分析、化学成分分析、金相检验及硬度测试等方法对开裂柱塞套进行了分析。结果表明：柱塞套在淬火加热过程中局部过热,引起显微组织及奥氏体晶粒粗大,降低了材料的强度,导致在柱塞套淬火过程中引起淬火裂纹。最后提出了改进建议。

There are more than ten plungers bushing cracking after grinding. The methods of macro-examination,chemical composition analysis,metallographic examination and hardness testing are employed to analyze cracked plunger bushing. The results showed that plunger bushing took place local overheat in heating process. Because of the local overheat,microstructure and austenite become coarse,reduce fracture resistance of material and increase cooling stress. These factors cause plunger busing to produce crack in quenching process. According to the analysis results,the improvement suggestions are put forward.