航空发动机涡轮盘轮缘凸块塑性变形失效分析

Plastic Deformation Failure Analysis of Flange Bumps of Aeroengine Turbine Disk

针对某航空发动机在工作过程中发生的涡轮盘轮缘凸块局部异常塑性变形故障,对故障涡轮盘进行失效分析。在此基础上,通过开展无应力及附加应力的加热模拟试验,总结了GH4169合金组织中δ相的3种析出形貌,以及加热温度、时间、应力3种因素对δ相析出的影响规律。通过对比硬度测试及温色试验结果,明确了GH4169合金试样在700℃以下组织和硬度无明显变化,但颜色变化明显;在700℃以上,随着δ相析出量的增加其硬度不断减小,而颜色却几乎无变化。结果表明:故障涡轮盘轮缘凸块部位的塑性变形是由于发动机工作过程中超温引起的,故障部位的实际工况达到了约750℃、100 h左右的超温。落实改善涡轮盘轮缘的冷却环境、提高涡轮部件加工及装配精度的改进措施后,涡轮盘通过了首翻期加速模拟、经起飞状态摸底和适航状态长时试车验证,无类似故障再次发生。

Aiming at the local abnormal plastic deformation failure of the flange bumps of the turbine disk during the working process of an aeroengine,the failure analysis of the failed turbine disk was carried out.On this basis,through the heating simulation test without stress and additional stress,three precipitation morphologies ofδphase of GH4169 alloy were summarized.The influence law of the heating temperature,time and stress onδphase precipitation was summarized.By comparing the results of hardness test and warm color test,it was clear that the microstructure and hardness of GH4169 alloy sample had no obvious change below 700℃,but the color change was obvious.Above 700℃,with the increase ofδphase precipitation,its hardness decreased continuously,but its color hardly changed.The results show that the plastic deformation of the flange bumps of the failed turbine disk is caused by the overtemperature during the engine working process.The actual working condition of the failed location reaches the overtemperature of about 750℃and about 100 hours.After imple⁃menting the improvement measures to improve the cooling environment of the turbine disk rim and improve the machining and assembly ac⁃curacy of turbine components,the turbine disk has passed the acceleration simulation in the first turning period,assessment test in the take-off state and the long-term commissioning verification in the airworthiness state,and no similar failures have occurred again.