Small objects of an alloy tool steel were built by selective laser melting at different scan speeds, and their microstructures were analyzed using electron backscatter diffraction (EBSD). To present an explicit correlation with the local thermal cycles in the objects, prior austenite grains were reconstructed using the EBSD mapping data. Extensive growth of austenitic grains after solidification could be detected by the disagreement between the networks of carbides and austenite grain boundaries. A rapid laser scan at 2000 mm/s led to less growth, but retained a larger amount of austenite than a slow one at 50 mm/s. The rapid scan also exhibited definite evolution of Goss-type textures in austenite, which could be attributed to the growth of austenitic grains under a steep temperature gradient. The local variations in the microstructures and the textures enabled us to speculate the locally different thermal cycles determined by the different process conditions, that is, scan speeds.
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机译：通过以不同的扫描速度熔化选择合金工具钢的小物体，并使用电子背散射衍射（EBSD）分析它们的微观结构。为了呈现与物体中的局部热循环的显式相关性，使用EBSD映射数据重建先前的奥氏体晶粒。通过碳化物网络和奥氏体晶界网络之间的分歧，可以检测到奥氏体颗粒的广泛生长。 2000 mm / s的快速激光扫描导致增长较低，但保留较大量的奥氏体，而不是50 mm / s的慢速。快速扫描还表现出奥氏体中高涨纹理的明确演变，这可能归因于陡峭温度梯度下奥氏体颗粒的生长。微结构和纹理中的局部变型使我们能够推测由不同的过程条件确定的局部不同的热循环，即扫描速度。
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