【摘要】 采用无余量整体熔模铸造技术,成功制备出了用于某大型运载火箭发动机上的涡壳体精铸件,为了全面分析工艺的可行性,试验研究了不同截面的显微组织。结果表明:涡壳体整体上由等轴晶组成,不同截面组织均呈现枝晶特征,试验测定了二次枝晶间距,并预测了截面冷却速率与枝晶间距的关系。在较高倍数下,进、出口法兰截面组织,发现有较多的针状δ相存在,枝晶间处的γ"相尺寸较大,数量较多,枝晶干处的γ"相尺寸较小,数量较少;涡形流道截面的针状δ相很少,枝晶干及枝晶间的γ"相尺寸均较小,数量无明显差别。这些其实质与各截面的冷却速率有关。更多还原

【Abstract】 The microstructure of K4169 volute at different sections for investment casting has been investigated in order to analyze the process feasibility. The results show that the microstructure of the whole casting is equiaxed grains, different sections all present dendritic crystal features, secondary dendrite arm spacing(SDAS)is measured, and the relationship between SDAS and cooling rate is predicted. At higher magnification, more acicular δ phases exist in the sections of inlet flange and outlet flange, in which interdendritic γ" phases are large in size and number; however, at the dendrite arm γ" phases are small in size and number. There are a few δphases in section of volute runner, and γ" phases in interdendritic region and dendritic arm are small in size, and their numbers have not significant difference. Meanwhile, these results are associated with the cooling speed of volutes sections in essence.更多还原