Modelling Creep and Creep Crack Growth of LPBF alloy 718

通过激光粉末床制造（LPBF）制造的部件从根本上受到其在关键应用中使用的性能的限制。对于通过LPBF生产的高温材料，微观结构缺陷（例如不利的沉淀物形成、次优的晶粒尺寸和分布）和宏观尺度异常（例如缺乏熔合、层内/层间缺陷）通常会导致LPBF部件的性能远低于其锻造部件。在这项工作中，使用四激光雷尼绍机器以不同的扫描策略制造合金718零件，构建方向和激光器数量，在600 MPa载荷下在650 ℃下进行蠕变测试。对于给定的策略，观察到与锻造合金718相比蠕变寿命增加24%。在蠕变破坏机理中，构造取向也是一个决定性因素。蠕变和蠕变裂纹扩展的模拟工作正在进行中。因此，作为这项工作的结果，有可能提出高温蠕变应用的构建策略，并能够准确地预测LPBF合金的蠕变性能。

Components manufactured by laser powder bed fabrication (LPBF) are fundamentally limited by their performance for use in critical applications. With respect to high temperature materials produced via LPBF, microstructural defects - such as unfavourable precipitate formation, suboptimal grain size and distribution - and macroscale anomalies - like lack of fusion, intra/inter layer defects - often result in LPBF components performing well below their wrought counterparts.In this work, alloy 718 parts, fabricated using a quad-laser Renishaw machine with different scanning strategies, build orientations and number of lasers, were creep tested at 650 under a 600 MPa load. For a given strategy, a 24% increase in creep life compared to wrought alloy 718 was observed. The build 0rientation was also shown to be a determining factor in the creep failure mechanism.Modelling of creep and Creep crack growth work is underway. It is therefore possible, as a result of this work, to propose build strategies for high temperature creep applications and be able to accurately predict LPBF alloys creeep performance.