Microporosity effects on cyclic plasticity and fatigue of LENS™-processed steel

An overview of Direct Laser Deposition for additive manufacturing; Part II: Mechanical behavior, process parameter optimization and control

“…The adjacent large discontinuities in some specimens also reduced the fatigue incubation life, dominating the HCF regime [38]. Xue et al [38] attributed the scatter in total fatigue life data to the scatter in the fatigue incubation lives, as they did not observe much microstructural effects on the fatigue crack growth stage for crack lengths of a > 1.4 mm.…”

“…Xue et al [38] used X-ray computed tomography to capture average and maximum values of pore size, pore density (number of pore per mm 2 ), and porosity fractions, as well as the shape of each pore. The pore shape is characterized by the sphericity coefficient, λ, which quantifies the resemblance of the pore to a perfect sphere [38]. They investigated the fatigue behavior as well as the upper and lower bounds for the predicted strain-life curves using the MSF model by varying the incubation pore porosity and size.…”

“…This microstructure-sensitive capability was used to formulate different stages of fatigue damage in LBAM components [38]. Xue et al [38] used X-ray computed tomography to capture average and maximum values of pore size, pore density (number of pore per mm 2 ), and porosity fractions, as well as the shape of each pore. The pore shape is characterized by the sphericity coefficient, λ, which quantifies the resemblance of the pore to a perfect sphere [38].…”

“…Here, Inc is the number of cycles to incubate a crack The MSF model predicts fatigue damage in materials based on microstructural inclusions, porosity, dendrite cell size (DCS), and nearest neighbor distance (NND) [129,132]. This microstructure-sensitive capability was used to formulate different stages of fatigue damage in LBAM components [38]. Xue et al [38] used X-ray computed tomography to capture average and maximum values of pore size, pore density (number of pore per mm 2 ), and porosity fractions, as well as the shape of each pore.…”

Evaluation of fracture toughness and impact toughness of laser rapid manufactured Inconel-625 structures and their co-relation

“…Blackwell and Wisbey [2] reported tensile strength and fracture toughness of Ti-6Al-4V alloy structures fabricated by LENS process. Xeu et al have reported that presence of unmelted/partially melted particles adversely affect fatigue life of LENS-processed structures [11]. Theriault et al studied uni-axial fatigue behavior of laser consolidated IN-625 structure at room and elevated temperatures [12].…”