Short crack propagation analysis and fatigue strength assessment of additively manufactured materials: An application to AISI 316L

Bergant, Marcos Antonio; Werner, Tiago; Madia, Mauro; Yawny, A.; Zerbst, Uwe

doi:10.1016/j.ijfatigue.2021.106396

Cited by 24 publications

(10 citation statements)

References 37 publications

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“…For future work on hybrid manufactured PBF-LB/M stainless steels and industrial applications, the authors recommend the application of local fatigue assessment methods either based on short fatigue crack growth models 52 or effective stress-based concepts in combination with models to account for production-related defects, for example, Schneller et al 53,54…”

Section: Discussionmentioning

confidence: 99%

Fatigue strength of PBF‐LB/M and wrought 316L stainless steel: effect of post‐treatment and cyclic mean stress

Braun

Mayer²,

Kryukov

et al. 2021

Fatigue Fract Eng Mat Struct

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Additive manufacturing (AM) enables the cost-effective production of complex components, many of which are traditionally manufactured using costly subtractive processes. During laser-based powder bed fusion of metals (PBF-LB/M), internal pores and rough surfaces are typically inevitable, reducing fatigue and corrosion resistance compared to traditional processes.Additionally, large defects often occur near to or at surfaces. Thus, this study investigates the effect of hybrid additive and subtractive manufacturing on the fatigue strength of AISI 316L. To this goal, different post-treatment routes are compared with wrought material. Additionally, computed tomography is used to determine the necessary machining depth of the surface layer. In this study, heat treatment and machining are both found to significantly increase fatigue strength (17% and 87%). Finally, the mean stress sensitivity M of as-built PBF-LB/M and wrought material is found to be highly affected by the assessed number of cycles to failure and residual stresses in PBF-LB/M material.

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Section: Discussionmentioning

confidence: 99%

Fatigue strength of PBF‐LB/M and wrought 316L stainless steel: effect of post‐treatment and cyclic mean stress

Braun

Mayer²,

Kryukov

et al. 2021

Fatigue Fract Eng Mat Struct

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“…In the design of the procedure for lowering the level of the durability curve, our objective was to use easily obtainable data from the analysed porous samples, so the necessary geometrical data on pore sizes, their position and orientation can be obtained by available non-destructive methods, such as X-ray imaging or by more advanced and accurate CT scans [ 21 ]. It should be noted that in our studies the detected macro-porosity was always larger than micro-defects [ 22 , 23 ], so this is a real analysis of the influence of structural porosity and not so much a material analysis. The specimens were manufactured using a high-pressure die-casting (HPDC) process in the CIMOS d.d.…”

Section: Methodsmentioning

confidence: 84%

Estimate of Coffin–Manson Curve Shift for the Porous Alloy AlSi9Cu3 Based on Numerical Simulations of a Porous Material Carried Out by Using the Taguchi Array

Tomažinčič

Klemenc

2022

Materials

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In real engineering applications, machine parts are rarely completely homogeneous; in most cases, there are at least some minor notch effects or even more extensive inhomogeneities, which cause critical local stress concentrations from which fatigue fractures develop. In the present research, a shift of the Coffin–Manson εa–N material curve in a structure with random porosity subjected to dynamic LCF loads was studied. This allows the rest of the fatigue life prediction process to remain the same as if it were a homogeneous material. Apart from the cyclic σ–ε curve, which is relatively easy to obtain experimentally, the εa–N curve is the second most important curve to describe the correlation between the fatigue life N and the strain level εa. Therefore, the correct shift of the εa–N curve of the homogeneous material to a position corresponding to the porous state of the material is crucial. We have found that the curve shift can be efficiently performed on the basis of numerical simulations of a combination of five porosity-specific geometric influences and the associated regression analysis. To model the modified synthetic εa–N curve, five geometric influences of porosity by X-ray or μ-CT analysis are quantified, and then the porosity-adjusted coefficients of the Coffin–Manson equation are calculated. The proposed approach has been successfully applied to standard specimens with different porosity topography.

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“…37 Elongated grains, often seen in the additive manufactured 316L due to the epitaxial growth following the thermal gradient direction, have negligible influence on the macroscopic yield behavior. 38 Numerous investigations concerning the high cycle fatigue (HCF) behavior of L-PBF 316L have attributed the dominant source of fatigue failure to the inherent defect, [39][40][41][42] while the role of AM microstructure has been less discussed. The evolution of texture and porosity was characterized during uniaxial tensile loading of 316L using in situ μ-CT and high energy X-ray diffraction in the work of Leonard et al 43 This study shows that elastic strains accumulate more in the grains oriented in {200} direction and less in the grains oriented in the {111} and {220} directions under monotonic tensile loading.…”

Section: Introductionmentioning

confidence: 99%

Correlation between microstructure and cyclic behavior of 316L stainless steel obtained by Laser Powder Bed Fusion

Liang

Hor

Robert

et al. 2022

Fatigue Fract Eng Mat Struct

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In this work, stainless steel 316L obtained by Laser Powder Bed Fusion (L-PBF) has been produced and characterized. The experimental campaign focuses on the samples in the as-built state under cyclic tension-compression loadings. Low cycle fatigue (LCF) and high cycle fatigue (HCF) tests are carried out. Microstructure observations are performed before and after the loadings. As-built L-PBF 316L has a good LCF performance despite the presence of surface defects but a low fatigue limit in the HCF regime. Removing the surface roughness has a beneficial effect but does not improve the fatigue strength to that of machined wrought 316L. Observations on the microstructure of fatigue samples indicate that LCF is dominated by the local plastic deformation, which is mostly achieved by the slip in the studied material and is not sensitive to the defect. The lack-of-fusion defect impairs the fatigue resistance in the HCF regime.

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Short crack propagation analysis and fatigue strength assessment of additively manufactured materials: An application to AISI 316L

Cited by 24 publications

References 37 publications

Fatigue strength of PBF‐LB/M and wrought 316L stainless steel: effect of post‐treatment and cyclic mean stress

Fatigue strength of PBF‐LB/M and wrought 316L stainless steel: effect of post‐treatment and cyclic mean stress

Estimate of Coffin–Manson Curve Shift for the Porous Alloy AlSi9Cu3 Based on Numerical Simulations of a Porous Material Carried Out by Using the Taguchi Array

Correlation between microstructure and cyclic behavior of 316L stainless steel obtained by Laser Powder Bed Fusion

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