调整浇注工艺调整与控制碳含量对抑制K4648合金稳定器热疲劳裂纹萌生的研究

Study on Effect of Pouring Parameters and Carbon-Content for K4648 Cast Super-Alloy Stabilizator Heat Fatigue Initiation

通过对航空发动机加力稳定器(K4648合金制)人工断口的显微形貌观察,发现断口形貌符合典型的疲劳断口特征,失效模式为热疲劳断裂。开展了针对调整浇注参数及控制碳含量以改善合金热疲劳性能的的研究。结果表明:降低浇注温度与提高模具温度均可有效减小晶粒尺寸,且组织形态也发生相应的变化。外置保温套与提高模具温度可促进晶界连续碳化物向链状转变;而降低碳含量促进合金组织均匀化程度升高,且晶界碳化物含量减少,晶内片层状α-Cr部分发生球化。调整浇注参数与降低碳含量对抑制合金热疲劳裂纹均有效。施加保温套,提高模壳温度并降低合金碳含量后的综合效果更佳。

Microstructure observation was performed on aero-engine stabilizator( produce by K4648 castsuperalloy).The fracture mode was fatigue failure. And cracks were caused by heat circulation. Adjustment of pouring parameters and carbon content were carried out to improve K4648 cast-superalloy fatigue resistance property. Result showed that Grain size decreased due to reduction pouring temperature orenhancingmould temperature And solidification structure changed. Application of insulation layer and enhancing mould temperature resultingrain-boundary network carbide transformed to chain carbide. Grain microstructure homogenization increased as a result of reduction of carbon content. And α-Cr Lamellar changed to sphere gradually. Application of insulation sleeveand enhancing matrix temperature,as well as reduce carbon content was ofexcellent effect in modification of heat fatigue resistance property for K4648 cast-supperalloy.