This work explores the feasibility of additively manufacturing tailored microstructures through varying process parameters, to eventually control the mechanical properties and performance. The investigation focuses on controlling the heat input and thermal history during laser-powder bed fusion of IN718 through process parameter manipulation; notably the heat input parameters (power, scan speed, and hatch spacing) and island scanning parameters (island size, shift, and island overlap). The changes in preferred orientation, morphology and grain size were characterised in both the transverse and build cross-sections using scanning electron microscopy (SEM) and electron back scatter diffraction (EBSD), while the texture development was comparatively characterised using X-ray diffraction (XRD). The solidification cell size was quantified to estimate the influence of the process parameters on the cooling rates. This was also rationalised using a thermal model resolving the scan characteristics to provide the transient temperature distribution to a numerical grain growth model. Based on the obtained microstructures, graded microstructures were generated using the island strategy and identical laser parameters throughout but changing subtle features such as the island size and shift. A suitable post-process heat treatment was applied to retain the tailored microstructures, while obtaining the required hardness.

这项工作探索了通过变化的工艺参数来增材制造量身定制的微结构，以最终控制机械性能和性能的可行性。这项研究的重点是通过工艺参数控制来控制IN718激光粉床熔合过程中的热量输入和热历史。尤其是热量输入参数（功率，扫描速度和舱口间距）和孤岛扫描参数（岛大小，偏移和孤岛重叠）。使用扫描电子显微镜（SEM）和电子反向散射衍射（EBSD）可以在横截面和构建横截面中表征优选取向，形态和晶粒尺寸的变化，而使用X射线衍射可以比较地表征织构的发展（ XRD）。量化凝固单元的尺寸以估计工艺参数对冷却速率的影响。使用解析扫描特征的热模型也可以对此进行合理化处理，以将瞬态温度分布提供给数值晶粒生长模型。基于获得的微结构，使用孤岛策略和相同的激光参数在整个过程中生成渐变的微结构，但是会改变细微的特征，例如孤岛的大小和偏移。进行适当的后处理热处理，以保留定制的微结构，同时获得所需的硬度。基于获得的微结构，使用孤岛策略和相同的激光参数在整个过程中生成渐变的微结构，但是会改变细微的特征，例如孤岛的大小和偏移。进行适当的后处理热处理，以保留定制的微结构，同时获得所需的硬度。基于获得的微结构，使用孤岛策略和相同的激光参数在整个过程中生成渐变的微结构，但是会改变细微的特征，例如孤岛的大小和偏移。进行适当的后处理热处理，以保留定制的微结构，同时获得所需的硬度。