17-4 precipitation hardening (PH) stainless steel is a multi-purpose engineering alloy offering an excellent trade-off between strength, toughness, and corrosion properties. It is commonly employed in additive manufacturing via laser powder bed fusion owing to its good weldability. However, there are remaining gaps in the processing-structure-property relationships for AM 17-4 PH that need to be addressed. For instance, discrepancies in literature regarding the as-built microstructure, subsequent development of the matrix phase upon heat treatment, as well as the as-built residual stress should be addressed to enable reproducible printing of 17-4 builds with superior properties. As such, this work applies a comprehensive characterisation and testing approach to 17-4 PH builds fabricated with different processing parameters, both in the as-built state and after standard heat treatments. Tensile properties in as-built samples both along and normal to the build direction were benchmarked against standard wrought samples in the solution annealed and quenched condition (CA). When testing along the build direction, higher ductility was observed for samples produced with a higher laser power (energy density) due to the promotion of interlayer cohesion and, hence, reduction of interlayer defects. Following the CA heat treatment, the austenite volume fraction increased to ∼35%, resulting in a lower yield stress and greater work hardening capacity than the as-built specimens due to the transformation induced plasticity effect. Neutron diffraction revealed a slight reduction in the magnitude of residual stress with laser power. A concentric scanning strategy led to a higher magnitude of residual stress than a bidirectional raster pattern.

中文翻译：

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激光粉末床熔合17-4PH不锈钢显微组织、力学性能和残余应力的相关性

17-4 沉淀硬化 (PH) 不锈钢是一种多用途工程合金，在强度、韧性和腐蚀性能之间实现了出色的平衡。由于其良好的可焊性，它通常用于通过激光粉末床熔合进行增材制造。然而，AM 17-4 PH 的加工-结构-性能关系中仍存在一些空白需要解决。例如，文献中有关竣工微观结构、热处理时基体相的后续发展以及竣工残余应力的差异应得到解决，以便能够以优异的性能重复打印 17-4 模型。因此，这项工作对采用不同工艺参数制造的 17-4 PH 结构应用了全面的表征和测试方法，无论是在竣工状态还是在标准热处理后。竣工样品沿和垂直于构建方向的拉伸性能均以固溶退火和淬火条件 (CA) 下的标准锻造样品为基准。当沿着构建方向进行测试时，由于层间粘合力的促进以及层间缺陷的减少，用较高激光功率（能量密度）生产的样品观察到较高的延展性。 CA热处理后，奥氏体体积分数增加至~35%，由于相变诱导塑性效应，与竣工样品相比，屈服应力更低，加工硬化能力更大。中子衍射显示残余应力的大小随着激光功率的增加而略有减小。同心扫描策略比双向光栅模式产生更高的残余应力。