Computing the Durability of WAAM 18Ni-250 Maraging Steel Specimens with Surface Breaking Porosity

Peng, Daren; Champagne, Victor K.; Ang, Andrew Siao Ming; Birt, Aaron; Michelson, Alex; Pinches, Samuel; Jones, Rhys

doi:10.3390/cryst13030443

Cited by 10 publications

(13 citation statements)

References 47 publications

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“…Furthermore, long cracks usually have longer plastic wake that reduces the crack growth rate due to the crack closure effect [31]. Work in [19,[38][39][40][41] has demonstrated that the variability in crack growth rates can be modelled using the modified Hartman-Schijve equation. In this work, Equation ( 6) was used to compute the variability in the crack growth rates in WAAM Ti64, where the material constants D and p were obtained from long crack test data [30].…”

Section: Life Prediction Methodsmentioning

confidence: 99%

Predicting the Effect of Surface Waviness on Fatigue Life of a Wire + Arc Additive Manufactured Ti-6Al-4V Alloy

et al. 2023

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This paper reports the effect of as-deposited surface conditions on the fatigue strength of an additively manufactured titanium alloy, Ti-6Al-4V (WAAM Ti64). First, the local stress concentration caused by the surface waviness was quantified using a metrology technique and computer modelling. Fatigue tests were conducted under bending loads at a cyclic load ratio of 0.1. The applicability of two predictive methods was the focus of this study. The traditional notch stress method was unable to predict the correct S–N curve trend slope, which could be attributed to the early crack initiation from the troughs on the as-built surface, with crack propagation being the dominant failure mechanism. By treating the troughs as small cracks, the fracture mechanics approach delivered good predictions at every applied stress level. Surface machining and polishing may not always be practical or required; it depends on the applications and service load levels. This research demonstrated that the fracture mechanics approach can be used for predicting the fatigue life of WAAM titanium alloys in as-built conditions and, hence, can be a tool for decision making on the level of surface machining.

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Section: Life Prediction Methodsmentioning

confidence: 99%

Predicting the Effect of Surface Waviness on Fatigue Life of a Wire + Arc Additive Manufactured Ti-6Al-4V Alloy

et al. 2023

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“…Similarly, Appendix X3 (contained) in the fatigue test standard ASTM E647-15el [45] notes that it is not clear if a fatigue threshold exists for small naturally occurring cracks. This finding has significant implications when assessing the durability of metallic airframes since it means that the crack growth equation needed to assess the durability can differ from that associated with the closure free crack growth curve, see [19] for more details. A more detailed discussion on the state of the art can be found in [61,98,99].…”

Section: The Relationship Between Plasticity Induced Crack Closure An...mentioning

confidence: 99%

“…As a result, the DADT assessment of conventionall manufactured, AM and CSAM parts must be based on the appropriate da/dN versus ∆K curve. However, it is now known [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] that the variability in the da/dN versus ∆K curves associated with the growth of long cracks in more than one hundred and twenty independent tests performed on a range of additively manufactured (AM) materialscan often be accounted for by expressing the crack growth rate (da/dN) as a function of ∆κ, where ∆κ is the Schwalbe crack driving force [21], and by allowing for the effect of the manufacturing process on just two parameters, namely the cyclic fatigue threshold and the fracture toughness. Here ∆κ is Schwalbe's crack driving force which is defined as:…”

Section: Introductionmentioning

confidence: 99%

“…The terms ∆K thr and A in Equation ( 1) are the fatigue threshold and the apparent cyclic fracture toughness respectively. The additively manufactured materials for which this observation has been found to hold include: Ti-6Al-4V [6,7,11,12], Inconel 718 [5], Inconel 625 [5], 316L steel [6,17,20], 304L steel [20], Aermet 100 steel [6], 17-4 Ph steel [15], Scalmalloy [12], an aluminium-scandium-magnesium alloy [4], 18Ni 250 Maraging steel [8,19]. This observation also appears to hold for a range of conventionally manufactured materials [22][23][24][25][26][27][28][29], a range of CSAM materials [20] and for plasma sprayed metals and alloys [30].…”

Section: Introductionmentioning

confidence: 99%

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On the Link between Plastic Wake Induced Crack Closure and the Fatigue Threshold

Jones,

Ang,

Phan

et al. 2024

Metals

Self Cite

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This purpose of this paper is to examine the relationship between crack growth equations based on Elber’s original plastic wake induced crack closure concept and the fatigue threshold as defined by the American Society for Testing and Materials (ASTM) fatigue test standard ASTM E647-15el. It is shown that, for a number of conventionally manufactured metals, the function U(R), where R is the ratio of the minimum to maximum applied remote stress, that is used to relate the stress intensity factor ΔK to the effective stress intensity factor ΔKeff is inversely proportional to the fatigue threshold ΔKth(R). This finding also results in a simple closed form equation that relates the crack opening stress intensity factor Ko(R) to ΔK, Kmax, and the fatigue threshold terms ΔKth(R) and ΔKeff,th. It is also shown that plotting da/dN as function of ΔK/ΔKth(R) would appear to have the potential to help to identify the key fracture mechanics parameters that characterise the effect of test temperature on crack growth. As such, for conventionally manufactured metals, plotting da/dN as function of ΔK/ΔKth(R) would appear to be a useful addition to the tools available to assess the fracture mechanics parameters affecting crack growth.

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“…Additive manufacturing (AM) has been rapidly developed in the past three decades thanks to the remarkable progress in computer technology and heat source development, which has gained widespread attention due to its high flexibility, high deposition efficiency, and high material utilization [1][2][3][4]. However, limited by the heat source and deposition characteristics, the solidification microstructure of the deposition is dominated by coarse columnar dendrite with significant directional growth due to the temperature gradient [5], leading to significant anisotropy [6], residual stress, and even deformation or crack.…”

Section: Introductionmentioning

confidence: 99%

A Progress in the Effect and Mechanism of Ultrasonic Impact Treatment on Additive Manufactured Metal Fabrications

Li-hua¹,

Huang²,

Wu³

et al. 2023

Preprint

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Metal fabrications experience complex physical metallurgical processes during additive manufacturing, leading to residual stress and coarse microstructure with directional growth. It significantly affects the comprehensive performance of the fabrications, which limits the application of additive manufacturing. Ultrasonic impact treatment (UIT), as a strengthening means to assist additive manufacturing, can effectively improve the stress state and refine the microstructure and the comprehensive performance. This paper introduces the effect of UIT on AM metal fabrications on microstructure morphology, stress distribution, surface roughness, internal defects, and comprehensive performance to gain a deeper understanding of the role of UIT on additively manufactured metal fabrications, which is based on the working principle and effect of process parameters. In addition, the strengthening mechanism of UIT in additive manufacturing is described from the perspective of surface plastic deformation and substructure formation, providing support for the shape and property control of metal fabrications in the process of additive manufacturing assisted by UIT. Finally, the issues that need to be studied in depth on UIT in additive manufacturing are summarized, and an outlook on future research directions is taken.

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Computing the Durability of WAAM 18Ni-250 Maraging Steel Specimens with Surface Breaking Porosity

Cited by 10 publications

References 47 publications

Predicting the Effect of Surface Waviness on Fatigue Life of a Wire + Arc Additive Manufactured Ti-6Al-4V Alloy

Predicting the Effect of Surface Waviness on Fatigue Life of a Wire + Arc Additive Manufactured Ti-6Al-4V Alloy

On the Link between Plastic Wake Induced Crack Closure and the Fatigue Threshold

A Progress in the Effect and Mechanism of Ultrasonic Impact Treatment on Additive Manufactured Metal Fabrications

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