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The use of laser powder bed fusion (LPBF) for faster and more customized manufacturing has grown significantly. However, LPBF parts often require welding to other components, raising concerns about their weldability due to differences in microstructure compared to conventionally manufactured parts. Despite its importance, research on the weldability of additive manufacturing materials remains limited. This study aims to evaluate the susceptibility of LPBF 316L stainless steel to weld solidification cracking using transverse varestraint testing and compare results with conventional 316L. Tests were conducted across strain levels from 0.5 to 7%, revealing a saturated strain of 4%, with maximum crack length (MCL), maximum crack distance (MCD), and total number of cracks (TNC) of approximately 0.36 mm and 31, respectively. Compared to existing literature, LPBF 316L produced with optimized printing parameters and low nickel equivalent content exhibited higher resistance to weld solidification cracking, reflected in lower MCL and MCD values. Cracks initiated at the solidus interface and propagated along the ferrite–austenite boundary under strain. Microstructural changes were observed after testing, transitioning from cellular austenitic solidification in LPBF to a skeletal ferrite-austenitic mode due to material remelting and slower cooling rates. These findings highlight that reduced nickel equivalent, alongside optimized printing parameters, contribute to enhanced weld solidification cracking resistance in LPBF 316L. This study advances understanding of the weldability of LPBF materials. 

Nickel-based alloys, Alloys 625 and 718, are widely used in the aerospace industry due to their excellent corrosion resistance and high strength at elevated temperatures. Recently, these alloys have been utilized to manufacture rocket engine components using additive manufacturing (AM) technologies such as laser powder bed fusion (LPBF) and powder-blown laser-based directed energy deposition (DED). These technologies offer faster and more cost-effective production while enabling the fabrication of near-net-shape parts that are subsequently joined by welding. However, solidification cracking susceptibility varies significantly between AM and conventionally processed materials, and limited weldability characterization has been conducted on AM-fabricated materials. This study assesses the weld solidification cracking susceptibility of Alloys 625 and 718 produced by wrought (mill-rolled), LPBF, and DED using transverse varestraint testing, Scheil-Gulliver simulations, the Crack Susceptibility Index (CSI), and the Flow Resistance Index (FRI). Transverse varestraint testing revealed that AM parts exhibited higher susceptibility due to the presence of larger and elongated grains in the fusion zone, affecting the weld solidification cracking response. In Alloy 625, the LPBF condition exhibited the highest maximum crack distance (MCD) of 2.35 ± 0.16 mm, compared to 1.56 ± 0.06 mm for wrought and 1.72 ± 0.10 mm for DED. Similarly, in Alloy 718, the DED condition showed the highest MCD of 2.93 ± 0.41 mm, while the wrought condition had an MCD of 2.01 ± 0.12 mm, and the LPBF condition reached 3.01 ± 0.33 mm at 5 % strain, without a clearly defined saturation strain. Although wrought materials demonstrated greater resistance to solidification cracking, solidification simulations did not correlate with the experimental testing, as they do not account for microstructural and mechanical factors, relying solely on chemistry.