Anisotropic multiaxial plasticity model for laser powder bed fusion additively manufactured Ti-6Al-4V

Wilson-Heid, Alexander E.; Qin, Shipin; Beese, Allison M.

doi:10.1016/j.msea.2018.09.077

Cited by 34 publications

(14 citation statements)

References 27 publications

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“…Selective laser melting (SLM) is a layer wise material addition technique that can generate complex 3D parts by selectively consolidating successive layers of powder materials on top of each other, using thermal energy supplied by a focused and computer-controlled laser beam [1][2][3]. SLM is also referred to as the laser powder bed fusion process (L-PBF) or laser beam melting (LBM) [1,4]. The competitive advantages of SLM include geometrical freedom and the ability to produce near-full density parts with high strength [5].…”

Section: Introductionmentioning

confidence: 99%

Thermal Fatigue Properties of H13 Hot-Work Tool Steels Processed by Selective Laser Melting

Wang

Wei

et al. 2020

Metals

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Currently, selective laser melting (SLM) is gaining widespread popularity as an alternative manufacturing technique for complex and customized parts, especially for hot-work and injection molding applications. In the present study, as the major factors for the failure of H13 hot-work die steels during hot-working, thermal fatigue (TF) properties of H13 processed by SLM and a conventional technique were investigated. TF tests (650 °C/30 °C) were conducted on the as-selective laser melted (As-SLMed), thermally treated selective laser melted (T-SLMed), and forged (Forged) H13. Results show that the As-SLMed H13 exhibited the best TF resistance properties among the specimens herein (the shortest total crack length and highest hardness of 687 ± 12 HV5), whereas the Forged H13 exhibited the poorest TF resistance properties (the longest total crack length and lowest hardness of 590 ± 11 HV5) after TF tests. TF resistance properties were closely related to the initial and final hardness. Further microstructural investigations revealed that the typical cell-like substructures, increased amount of retained austenite, and most importantly, refined grain size were the main reasons for the improved TF resistance properties in the As-SLMed H13 compared to the Forged counterparts.

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Section: Introductionmentioning

confidence: 99%

Thermal Fatigue Properties of H13 Hot-Work Tool Steels Processed by Selective Laser Melting

Wang

Wei

et al. 2020

Metals

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“…Calibrated plasticity models for 316L [17] and Ti-6Al-4V [19] were developed previously by the authors and used in simulations of each dense geometry using the finite element method in the commercial software Abaqus [21]; the complete model details for each fracture geometry are provided in Refs. [16][17][18]20].…”

Section: Finite Element Analysis Simulationsmentioning

confidence: 99%

“…The parameters A and n are parameters from the equations used to describe the rate of strain hardening in the plasticity models given in [17,19], and these values were held constant for each pore size, while c 1 , c 2 , c s θ , and c c θ were calibrated for each pore size in the current study. The parameters c 1 and c 2 have the same effect as in the stress-based MC model, and c s θ and c c θ control the Lode angle parameter dependence and asymmetry, respectively, of the calibrated fracture surfaces.…”

Section: Equivalent Plastic Strain Versus Stress Triaxiality and Lode Angle Spacementioning

confidence: 99%

“…In this study, the effect of pores relative to the behavior of dense samples was assessed in two different alloys using well-known fracture models calibrated in both equivalent stress and strain space. Data over a wide range of stress states from previous studies by the authors on L-PBF stainless steel 316L [16,17] and L-PBF Ti-6Al-4V [18][19][20] that included intentionally manufactured, penny-shaped pores of varying diameter were used to calibrate fracture models for each pore size in stress triaxiality versus Lode angle parameter versus equivalent stress space (Haigh-Westergaard space, referred to here as equivalent stress space) and equivalent strain space. By comparing the ductile 316L alloy (>60% engineering strain to failure under uniaxial tension) to the less ductile Ti-6Al-4V (<10% engineering strain to failure under uniaxial tension) in both equivalent stress and strain space as a function of pore size, an assessment of dominant fracture mechanism changes, if any, can be made for each material.…”

Section: Introductionmentioning

confidence: 99%

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Contrasting the Role of Pores on the Stress State Dependent Fracture Behavior of Additively Manufactured Low and High Ductility Metals

2021

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This study investigates the disparate impact of internal pores on the fracture behavior of two metal alloys fabricated via laser powder bed fusion (L-PBF) additive manufacturing (AM)—316L stainless steel and Ti-6Al-4V. Data from mechanical tests over a range of stress states for dense samples and those with intentionally introduced penny-shaped pores of various diameters were used to contrast the combined impact of pore size and stress state on the fracture behavior of these two materials. The fracture data were used to calibrate and compare multiple fracture models (Mohr-Coulomb, Hosford-Coulomb, and maximum stress criteria), with results compared in equivalent stress (versus stress triaxiality and Lode angle) space, as well as in their conversions to equivalent strain space. For L-PBF 316L, the strain-based fracture models captured the stress state dependent failure behavior up to the largest pore size studied (2400 µm diameter, 16% cross-sectional area of gauge region), while for L-PBF Ti-6Al-4V, the stress-based fracture models better captured the change in failure behavior with pore size up to the largest pore size studied. This difference can be attributed to the relatively high ductility of 316L stainless steel, for which all samples underwent significant plastic deformation prior to failure, contrasted with the relatively low ductility of Ti-6Al-4V, for which, with increasing pore size, the displacement to failure was dominated by elastic deformation.

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“…The orientation-dependent mechanical properties were extracted from the tensile tests of small cross-sectional Ti-6Al-4V. The plastic behavior of the SLMed small cross-sectional Ti-6Al-4V samples was quantitatively characterized using a digital image technique and was formulated using Hill's anisotropic yield function [21,22] . The corrected computer-aided design (CAD) models and a constitutive model were applied to a finite element (FE) model of uniaxial compression of the BCC lattice structure and sequentially validated by experiments.…”

Section: Introductionmentioning

confidence: 99%

Anisotropy of a Selective Laser-Melted Ti–6Al–4V Lattice Structure

Dingye¹,

Zhou²,

Ma³

et al. 2021

Preprint

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Selective laser melting (SLM) is a widely adopted additive manufacturing process for the preparation of metallic lattice structures. However, it causes a build-direction-dependent anisotropy of morphologies, microstructures, and mechanical properties, making it difficult to predict the behavior and performance of lattice structures. In this study, tensile samples with different cross-sections and build directions (BDs) were fabricated by SLM. The anisotropic morphology, microstructure, and tensile properties were observed and measured using optical microscopy, scanning electron microscopy, and three-dimensional digital image correlation to determine the effects of the size and BD of SLMed materials. The extracted data were sequentially used to modify the geometric and physical models of the lattice. Body-centered cubic lattice structures were fabricated by SLM, and compression tests were performed to verify the modified compression model. In addition to the BD-related grains, the cross-sectional area of the SLMed sample affects its mechanical properties. The small cross-section makes the microstructure finer because the proportion of the contour path that uses higher power is no longer negligible. The sample with small cross-section has more anisotropy because of the lack of tolerance to heterogeneity and macro defects like roughness. In this study, by analyzing samples with small cross-sections, a model consisting of an isotropic hardening law and Hill’s anisotropic yield function is established to describe the yield and plasticity behavior of the as-built SLMed Ti–6Al–4V lattice. The simulated and experimental data fit very well, verifying the methodology employed in this study.

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Anisotropic multiaxial plasticity model for laser powder bed fusion additively manufactured Ti-6Al-4V

Cited by 34 publications

References 27 publications

Thermal Fatigue Properties of H13 Hot-Work Tool Steels Processed by Selective Laser Melting

Thermal Fatigue Properties of H13 Hot-Work Tool Steels Processed by Selective Laser Melting

Contrasting the Role of Pores on the Stress State Dependent Fracture Behavior of Additively Manufactured Low and High Ductility Metals

Anisotropy of a Selective Laser-Melted Ti–6Al–4V Lattice Structure

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