Abstract Fabrication of single crystal (SC) Ni-based gas turbine blades with a minimum crystal misorientation has always been a challenge in gas turbine industry, due to its significant influence on high temperature mechanical properties. This paper reports an experimental investigation and numerical simulation of the SC solidification process of a Ni-based superalloy to study effects of withdrawal rate and starter block size on crystal orientation. The results show that the crystal misorientation of the sample with 40 mm starter block height is decreased with increasing withdrawal rate up to about 9 mm/min, beyond which the amount of misorientation is increased. It was found that the withdrawal rate, height of the starter block and temperature gradient are completely inter-dependent and indeed achieving a SC specimen with a minimum misorientation needs careful optimization of these process parameters. The height of starter block was found to have higher impact on crystal orientation compared to the withdrawal rate. A suitable withdrawal rate regime along with a sufficient starter block height was proposed to produce SC parts with the lowest misorientation.

中文翻译：

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拉拔速率和起始块尺寸对单晶镍基高温合金晶体取向的影响

摘要 制造具有最小晶体取向差的单晶 (SC) Ni 基燃气轮机叶片一直是燃气轮机行业面临的挑战，因为它对高温机械性能有显着影响。本文报告了一项镍基高温合金 SC 凝固过程的实验研究和数值模拟，以研究拉拔速率和起始块尺寸对晶体取向的影响。结果表明，起始块高度为 40 mm 的样品的晶体取向差随着拔出速率的增加而降低，最高可达约 9 mm/min，超过该值，取向误差量增加。结果发现，提款率，起始块的高度和温度梯度是完全相互依赖的，并且确实需要对这些工艺参数进行仔细优化才能获得具有最小定向误差的 SC 样品。发现起始块的高度与提取速率相比对晶体取向具有更大的影响。提出了合适的拔出率制度以及足够的起始块高度，以生产具有最低错误定向的 SC 部件。