PSI - Issue 82

J. Blankenhagen et al. / Procedia Structural Integrity 82 (2026) 37–43 Blankenhagen et al. / Structural Integrity Procedia 00 (2026) 000–000

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1. Introduction

In modern structural engineering, significant potential lies in improving the performance of framework nodes, which often determine the required dimensions of connecting members to safely carry applied loads. Additive manu facturing (AM) o ff ers a promising approach to enhance node design and performance. Through the use of Powder Bed Fusion of Metals using a Laser Beam (PBF-LB / M), highly optimized geometries and intricate internal structures, such as lattices, can be fabricated with exceptional precision. The near-unlimited design freedom of PBF-LB / Menables localized optimization of nodes, thereby reducing the overall material consumption of the global structure. PBF-LB / M is an additive manufacturing process in which metallic components are produced layer by layer through the selective melting of metal powder using a focused laser beam. A thin powder layer is evenly distributed over the build platform within an inert gas atmosphere to prevent oxidation. The laser then scans the defined cross-section of each layer, melting and fusing the powder according to the part geometry. The process is characterized by ex tremely high solidification rates and steep thermal gradients, which lead to the formation of fine cellular or columnar microstructure (Krakhmalev et al. (2018)). After each layer is completed, the build platform is lowered by the layer thickness—typically 20–60 µ m—and the procedure is repeated until the final component is completed. Among the materials suitable for PBF-LB / M, 316L stainless steel remains the most widely used due to its excellent printability, mechanical stability, and corrosion resistance. However, its moderate strength limits its application in high-performance structures. Recently, new alloys specifically developed for AM have emerged. One example is the (C + N) austenitic stainless steel Printdur ® HSA, which exhibits superior static mechanical properties compared to 316L while maintaining good ductility. The layer-wise manufacturing approach in PBF-LB / M inherently a ff ects the resulting material properties. Previous studies have shown that both the static mechanical behavior and the fatigue performance of PBF-LB / M 316L depend heavily on the orientation of loading relative to the build direction (Charmi et al. (2021); van Nuland et al. (2021); Blinn et al. (2018)). However, fracture mechanics characteristics, such as crack propagation behavior and fracture toughness, remain insu ffi ciently researched. These parameters are crucial for designing reliable and durable load bearing components. Only a limited number of studies have investigated the fracture mechanics behavior of additively manufactured 316L—specifically those by Riemer et al. (2016); Suryawanshi et al. (2017); Fergani et al. (2018); Reschetnik et al. (2019); Kluczyn´ski et al. (2020) for crack propagation and by Suryawanshi et al. (2017); Alsalla et al. (2018) for fracture toughness. The majority of these studies report an improvement in crack growth resistance when the notch, respectively the direction of the crack, is perpendicular to the build direction. As a first step in addressing this research gap, the present study investigates the fatigue crack growth behavior of additively manufactured Printdur ® HSA and compares it with conventionally produced (C + N) steels, as well as with 316L in both additive and conventional forms.

Nomenclature

∆ K Stress intensity factor range PBF-LB / M Powder Bed Fusion of Metals using a Laser Beam AHIS Austenitic High-Interstitial Steels AHNS Austenitic High-Nitrogen Steels CT Compact Tension COD Crack Opening Displacement m Slope of the Paris law curve C Intercept (material constant) in the Paris law K IC Fracture toughness J IC J-integral fracture toughness