Development of microstructures in Fe−15Ni−15Cr single crystal electron beam welds
Development of microstructures in Fe−15Ni−15Cr single crystal electron beam welds
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DOI：
10.1007/bf02650147
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发表时间：
1989-06
期刊：
影响因子：
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通讯作者：
M. Rappaz;S. David;J. Vitek;L. Boatner
中科院分区：
文献类型：
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作者：
M. Rappaz;S. David;J. Vitek;L. Boatner
为了研究生长晶体学和凝固行为之间的关系，对Fc−15Ni−15Cr自生焊接单晶中产生的微观结构进行了详细分析。在[100]或[110]方向的单晶（001）表面上以不同的速度进行电子束焊接。进行了几何分析，以便在三个方向上的枝晶生长速度<100>的焊接速度为不同的结晶取向检查。根据该分析，基于最小速度或最小过冷标准，将优选的枝晶主干方向确定为凝固前沿方向的函数。一个彻底的检查焊缝显微组织和比较与在这项工作中开发的几何关系允许进行三维重建的焊池形状。此外，枝晶间距进行了测量，并作为生长速度的函数的间距的变化进行了比较与理论预测。结果发现，在该范围内的枝晶生长的速度预期与实验结果一致，而且，此外，枝晶间距与生长速度的变化与理论预测的不同。这些结果清楚地表明了晶体学对熔池凝固过程中微观组织发展的影响。结果还表明，所得到的显微组织和池的形状可以解释的几何分析结合现有的凝固模型。
A detailed analysis of the microstructures produced in an autogenously welded single crystal of Fc−15Ni−15Cr was performed in order to investigate the relationship between growth crystallography and solidification behavior. Electron beam welds were made at various speeds on the (001) surface of single crystals in either the [100] or [110] directions. A geometrical analysis was carried out in order to relate the dendrite growth velocities in the three <100> directions to the weld velocities for the different crystallographic orientations examined. From this analysis, the preferred dendrite trunk directions were determined as a function of the solidification front orientation based upon a minimum velocity or minimum undercooling criterion. A thorough examination of the weld microstructures and a comparison with the geometrical relationships developed in this work permitted a three-dimensional reconstruction of the weld pool shape to be performed. In addition, the dendrite spacings were measured, and the variation in spacings as a function of growth velocity was compared with theoretical predictions. It was found that the range of velocities over which dendritic growth is expected agreed with the experimental findings, and, furthermore, the change in dendrite spacing with growth velocity varied as predicted by theory. These results clearly demonstrate the effect of crystallography on the micro-structural development during weld pool solidification. The results also show that the resultant microstructures and pool shapes can be explained by geometrical analysis in conjunction with existing solidification models.