Laser-directed energy deposition (L-DED) is a key enabling technology for the repair of high-value aerospace components, as damaged regions can be removed and replaced with additively deposited material. While L-DED repair improves strength and fatigue performance compared to conventional subtractive techniques, mechanical performance can be limited by process-related defects. To assess the role of oxygen on defect formation, local and chamber-based shielding methods were applied in the repair of 300M high strength steel. Oxidation between layers for locally shielded specimens is confirmed to cause large gas pores which have deleterious effects on fatigue life. Such pores are eliminated for chamber shielded specimens, resulting in an increased ductility of ∼15%, compared to ∼11% with chamber shielding. Despite this, unmelted powder defects are not affected by oxygen content and are found in both chamber- and locally shielded samples, which still have negative consequences for fatigue.

激光定向能量沉积 (L-DED) 是修复高价值航空航天部件的关键技术，因为受损区域可以被去除并用增材沉积材料替换。虽然与传统减材技术相比，L-DED 修复可提高强度和疲劳性能，但机械性能可能会受到工艺相关缺陷的限制。为了评估氧气对缺陷形成的作用，在 300M 高强度钢的修复中应用了局部和基于室的屏蔽方法。局部屏蔽样本的层间氧化被证实会导致大的气孔，这对疲劳寿命产生有害影响。室屏蔽样品消除了此类孔隙，导致延展性增加约 15%，而室屏蔽样品的延展性增加约 11%。尽管如此，未熔化的粉末缺陷不受氧含量的影响，并且在腔室和局部屏蔽的样品中都存在，这仍然对疲劳产生负面影响。