Hot dwell-fatigue behaviour of additively manufactured AlSi10Mg alloy: Relaxation, cyclic softening and fracture mechanisms

Bao, Jianguang; Wu, Zhengkai; Wu, Shengchuan; Withers, Philip J.; Li, Fēi; Ahmed, Saad; Benaarbia, Adil; Sun, Wei

doi:10.1016/j.ijfatigue.2021.106408

Cited by 22 publications

(4 citation statements)

References 45 publications

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“…The T4 conditions tested at 0.0015 mm/mm were of particular interest as they display plastic deformation in their hysteresis loops for the first few hundred cycles after which their stress–strain response became fully elastic. The low volume fraction of Mg 2 Si precipitates in the T4 conditions, as has been reported in literature, 57 allowed rapid dislocation multiplication under cyclic loading leading to a cyclic hardening response 58,59 . In the T7‐475‐165 condition, the subsequent aging step below the Mg 2 Si solvus allowed the growth and formation of additional precipitates 58 .…”

Section: Discussionsupporting

confidence: 57%

“…The low volume fraction of Mg 2 Si precipitates in the T4 conditions, as has been reported in literature, 57 allowed rapid dislocation multiplication under cyclic loading leading to a cyclic hardening response. 58,59 In the T7-475-165 condition, the subsequent aging step below the Mg 2 Si solvus allowed the growth and formation of additional precipitates. 58 These precipitates, although were effective dislocation barriers under monotonic loading, could be sheared by the repetitive motion of dislocations in persistent slip bands leading to mechanical dissolution of precipitates over time under cyclic loading, which would possibly explain the softening response observed in the T7 condition.…”

Section: Fatigue Behaviormentioning

confidence: 99%

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Tensile and fatigue behaviors of additively manufactured AlSi10Mg: Effect of solutionizing and aging heat treatments

Baig

Ghiaasiaan

Shao

et al. 2023

Fatigue Fract Eng Mat Struct

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The effects of various heat treatments on the microstructure and mechanical properties of laser beam powder bed fused AlSi10Mg were investigated. Specimens were solutionized at three different temperatures of 425 C, 475 C, and 525 C followed by natural aging (T4) prior to microstructural and mechanical characterization. In addition, the effect of aging was studied by artificially aging (i.e., T7) some of the solutionized specimens at 165 C. Solutionizing at all temperatures was observed to fully dissolve the additive manufacturing (AM) induced dendritic microstructure, leaving bulky Si and needle-shaped β-AlFeSi precipitates in the grain interiors and boundaries. Tensile results revealed that T4 specimens exhibited more ductility, while T7 specimens showed substantially higher strengths with slightly reduced ductility. Interestingly, no significant effect of heat treatment on strain-life fatigue behavior was observed. Fractography found the Si particles to be responsible for tensile fracture, while AM volumetric defects were the main initiators of fatigue cracks.aluminum, fatigue, laser beam powder bed fusion (LB-PBF/L-PBF), microstructure, tensile Highlights• Effect of heat treatments on tensile and fatigue behavior of L-PBF AlSi10Mg studied.• T7 treatment led to higher tensile strengths than T4, but similar fatigue lives.• Tensile failure initiated from Si-particle fracture or debonding from matrix.• Fatigue life was affected by the size of crack initiators, that is, volumetric defects. | INTRODUCTIONAluminum alloys are commonly used in various industries because of their superior strength/stiffness to weight ratio compared to other alloys. 1,2 Among various Al alloys, AlSi10Mg as a cast alloy 2 has historically been used to fabricate complex/thin-walled geometries. Recently, processing AlSi10Mg through additive manufacturing (AM) has shown to be very promising as intricate, lightweight parts can be manufactured without

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Section: Discussionsupporting

confidence: 57%

Section: Fatigue Behaviormentioning

confidence: 99%

Tensile and fatigue behaviors of additively manufactured AlSi10Mg: Effect of solutionizing and aging heat treatments

Baig

Ghiaasiaan

Shao

et al. 2023

Fatigue Fract Eng Mat Struct

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“…As the temperature reaches 250°C, the number of dimples gradually increases and the color of dimples becomes darker. It shows that the dominated fractures mechanisms of the alloys are gradually transferred from the fragile fracture mechanism to the ductile dimple mechanism due to the stress relaxation and the microstructure homogenization induced by DRX increase as deformation temperatures elevated (Bao et al, 2021).…”

Section: Hot Tensile Fracture Morphology Of Alloymentioning

confidence: 99%

Hot Tensile Deformation Behavior of Mg-4Li-1Al-0.5Y Alloy

Yang

Wang

et al. 2021

Front. Mater.

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The microstructure evolution and deformation mechanism of the as-extruded-annealed Mg-4Li-1Al-0.5Y alloy (denoted as LAY410) were investigated during the hot tensile deformation at the temperatures between 150°C and 300°C with strains from 8 × 10−5 s−1 to 1.6 × 10−3 s−1. The results show that when the strain rate decreases and/or the deformation temperature increases, the peak stress of the alloy gradually decreases, and the elongations to fracture gradually increases. The true stress–strain curves show typical dynamic recrystallization (DRX) softening characteristics. It is observed that the microstructure in the magnesium (Mg) alloy deformed at 150°C is mainly composed of the deformed grains and a few recrystallized grains. The microstructures in the Mg alloy deformed at 200°C consisted of substructures and a slightly increasing number of dynamic recrystallized grains. When the deformation temperature reaches 250°C, the number of recrystallized grains increases significantly, and the microstructures are dominated by recrystallized grains. Moreover, through theoretical calculation and result analysis, the activation energy was about 99.3 kJ/mol, and the hot tensile deformation mechanism was the alternate coordinated deformation mechanism among grain boundary slip (GBS), intragranular slip, and DRX.

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“…An interesting study by Bao et al shows that the coarsening of the Si phase during a fatigue test at 400 °C can actually result in void formation that leads to fatigue failure, while fatigue life at lower temperatures was driven by existing porosity, as illustrated in Fig. 32 [144].…”

Section: Fatigue Lifementioning

confidence: 99%

A critical review on the effects of process-induced porosity on the mechanical properties of alloys fabricated by laser powder bed fusion

et al. 2022

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Laser powder bed fusion (LPBF) is an emerging additive manufacturing technique that is currently adopted by a number of industries for its ability to directly fabricate complex near-net-shaped components with minimal material wastage. Two major limitations of LPBF, however, are that the process inherently produces components containing some amount of porosity and that fabricated components tend to suffer from poor repeatability. While recent advances have allowed the porosity level to be reduced to a minimum, consistent porosity-free fabrication remains elusive. Therefore, it is important to understand how porosity affects mechanical properties in alloys fabricated this way in order to inform the safe design and application of components. To this aim, this article will review recent literature on the effects of porosity on tensile properties, fatigue life, impact and fracture toughness, creep response, and wear behavior. As the number of alloys that can be fabricated by this technology continues to grow, this overview will mainly focus on four alloys that are commonly fabricated by LPBF—Ti-6Al-4 V, Inconel 718, AISI 316L, and AlSi10Mg.

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Hot dwell-fatigue behaviour of additively manufactured AlSi10Mg alloy: Relaxation, cyclic softening and fracture mechanisms

Cited by 22 publications

References 45 publications

Tensile and fatigue behaviors of additively manufactured AlSi10Mg: Effect of solutionizing and aging heat treatments

Tensile and fatigue behaviors of additively manufactured AlSi10Mg: Effect of solutionizing and aging heat treatments

Hot Tensile Deformation Behavior of Mg-4Li-1Al-0.5Y Alloy

A critical review on the effects of process-induced porosity on the mechanical properties of alloys fabricated by laser powder bed fusion

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