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应用高速凝固定向凝固方法研究凝固工艺参数(抽拉速度、模壳保温温度)对DZ125高温合金铸件组织及性能的影响。结果发现,升高模壳保温温度可大幅度提高温度梯度,并制备出晶粒挺直度更为优良的铸件。枝晶组织及γ′析出相在壁厚较大部位更为粗大,且均随着抽拉速率及模壳保温温度的提高得到细化。显微偏析随抽拉速率的增加先减轻后加重,随模壳保温温度的提高部分元素偏析加重,部分元素减轻;γ+γ’共晶含量随抽拉速率的增大和模壳保温温度的提高而减少。铸件经标准热处理后,枝晶组织模糊不清,γ’析出相由于凝固参数变化而引起的差异显著减轻,且共晶组织几乎全部消除。抽拉速率变化对热处理态铸件性能无显著影响,但温度梯度的提高改善了铸件晶粒的挺直度,减小了晶粒偏离轴向的角度,提高了铸件性能。
The influence of solidification process parameters (draw speed, mold shell holding temperature) on the microstructure and properties of DZ125 superalloy casting was studied by high speed solidification directional solidification method. The results show that raising the temperature of the mold shell can greatly increase the temperature gradient, and to prepare a more excellent die straightness casting. The dendritic structure and γ ’precipitates were more coarse in the larger part of the wall thickness and were refined with the increase of the drawing rate and the temperature of the mold shell. The microsegregation first decreases and then increases with the increase of drawing rate, and some element segregation aggravates with the increase of holding temperature of the shell, and some of the elements reduce. The γ + γ ’eutectic content increases with the increase of drawing rate and the holding temperature of the shell And reduce. After the standard heat treatment, the dendrite structure is blurred, and the difference of γ ’precipitated phase due to the change of solidification parameters is significantly reduced, and the eutectic structure is almost eliminated completely. The change of draw rate had no significant effect on the properties of the heat-treated castings, but the improvement of the temperature gradient improved the straightness of the castings, reduced the deviation of the grains from the axial direction and improved the castability.