Effect of the deposition direction on fracture propagation in a Duplex Stainless Steel manufactured by Directed Energy Deposition

Dense volumes of duplex stainless steel are manufactured by directed energy deposition. Compact tension specimens machined from these in order to evaluate the fracture toughness two directions : parallel or perpendicular deposited layers. Different values measured cases. In understand this anisotropy, additional analyzes performed on cracked post-mortem. A classical metallography analysis reveals highly oriented structure material, as well phase localization. The study surface several points. At macroscale, while crack surfaces flat case, pronounced shear lips cover half case. microscale, is ruled microvoid coalescence. mesoscale, which inherited deposition strategy, found pilot growth. border between primary solidified melt pools and heat-affected zones, corresponds interface layers, preferred area for Analyzing roughness confirms dominance its characteristic lengthscale retrieved. This explains differences observed tested fracture: aligned with weak interfaces channel growth; orthogonal one, out-of-plane excursion becomes possible allowing follow a tortuous three-dimensional path that results higher than situation.