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利用Bridgman定向凝固工艺进行了高温合金DD483单晶叶片铸造试验,通过调整抽拉速度和使用不同型壳材料研究了工艺条件对杂晶缺陷的影响。结果表明,叶片中的杂晶缺陷一般出现在横截面突然扩大的缘板部位。铸件下部的外侧比内侧更易生成杂晶,但在上部则相反,即铸件内侧的杂晶缺陷更严重。在缘板部位降低抽拉速度能有效减少杂晶缺陷。在使用国产型壳时合金DD483叶片的单晶率非常低,但使用进口的纯刚玉型壳时叶片质量有明显提高,这说明型壳材料对单晶叶片中杂晶的形成有明显影响。
The Bridgman directional solidification process was used to simulate the casting of DD483 single-crystal superalloy. The influence of process conditions on the stray crystal defects was investigated by adjusting the drawing speed and using different shell materials. The results show that the streak defects in the leaves generally appear on the edge of the plate where the cross section is suddenly enlarged. The outer part of the lower part of the casting is more prone to the formation of miscellaneous crystals than the inner part, but the opposite of the upper part. Decreasing drawing speed in the edge plate can effectively reduce the stray defects. The single crystal rate of DD483 alloy was very low when domestically made, but the quality of imported pure corundum was significantly improved, which indicated that the shell material had a significant influence on the formation of spalled crystal in single crystal leaf.