铁基粉末冶金齿轮断裂失效分析及其工艺改进研究

Fracture failure analysis and process improvement of iron-based powder metallurgy gears

针对某型粉末冶金齿轮在运行期间出现的断齿现象,通过扫描电镜、能谱仪分析断口形貌、成分,发现断口位置存在大量球状铁碳化合物,表明原工艺由于烧结温度、时间不足,造成了粉末之间结合力弱的缺陷。在此基础上,以Fe-1.8Ni-0.5Mo-1.2Cu-0.2C预合金粉为研究对象,改进烧结工艺,采用压制、烧结、淬火与低温回火的新工艺,制备出的齿轮珠光体数量级别为珠60,热处理后齿轮组织由回火马氏体和铁素体组成,冲击韧性由9.8 J/cm^2提升至15.2 J/cm^2。结果表明,改进工艺能够显著提升粉末间的扩散、熔焊和再结晶效果,提高组织致密性和冲击韧性并使组织具有一定塑性。

The teeth of a powder metallurgy gear were fractured during operation.A large number of globular iron-carbon compounds were found at the fracture site using SEM and EDS analysis,which indicates a weak bonding between powders resulting from an insufficient sintering temperature and duration of the original process.An improved sintering process and a new process of pressing,sintering,quenching,and low-temperature tempering were applied to Fe-1.8Ni-0.5Mo-1.2Cu-0.2C prealloyed powder.The pearlite quantity in the prepared gear is 60,and the new prepared gear comprises tempered martensite and ferrite subsequent to heat treatment.The impact toughness improved from 9.8 J/cm^2 to 15.2 J/cm^2.