Effects of post-processing on cyclic fatigue response of a titanium alloy additively manufactured by electron beam melting

Xiaoli, Shui; Yamanaka, Kazushi; Mori, M.; Nagata, Yoshihiko; Kenya, Kurita; Chiba, Akihiko

doi:10.1016/j.msea.2016.10.059

Cited by 95 publications

(45 citation statements)

References 33 publications

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“…SLM specimens includes a stress relief at 650°C for several hours [19], which induces a complete decomposition of the martensite [18,20,21]. For both EBM and SLM parts, the presence of lack-of-fusion residual porosities can be addressed by HIP at 920°C, which results in a coarsening of the α lamellae and the β rods [15,22,23]. Stress relief and HIP have demonstrated their efficiency in increasing the ductility of AM parts [15,21,23].…”

Section: U N C O R R E C T E D P R O O Fmentioning

confidence: 99%

“…For both EBM and SLM parts, the presence of lack-of-fusion residual porosities can be addressed by HIP at 920°C, which results in a coarsening of the α lamellae and the β rods [15,22,23]. Stress relief and HIP have demonstrated their efficiency in increasing the ductility of AM parts [15,21,23]. However, they only enable a very limited control over the microstructure, which remains far from being optimized after post-processing.…”

Section: U N C O R R E C T E D P R O O Fmentioning

confidence: 99%

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Micromechanical behavior and thermal stability of a dual-phase α+α’ titanium alloy produced by additive manufacturing

et al. 2019

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In order to improve the tensile properties of additively manufactured Ti 6Al 4V parts, specific heat treatments have been developed. Previous work demonstrated that a sub-transus thermal treatment at 920°C followed by water quenching generates a dual-phase α+α′ microstructure with a high work-hardening capacity inducing a desirable increase in both strength and ductility. The present study investigates the micromechanical behavior of this α+α′ material as well as the thermal stability of the metastable α' martensite. To that end, annealing of the α+α′ microstructure is performed and the resulting microstructural evolution is analyzed, along with its impact on the tensile properties. A deeper understanding of the micromechanics of the multiphase microstructure both before and after annealing is achieved by performing in-situ tensile testing within a SEM, together with digital image correlation for full-field local strain measurements. This approach allows the strain partitioning to be quantified at a microscale and highlights a significant mechanical contrast between the two phases. In the α+α′ microstructure, the α′ phase is softer than the α phase, which is confirmed by nanoindentation measurements. Partial decomposition of the martensite during annealing induces a substantial hardening of the α′ phase, which is attributed to fine-scale precipitation and solution strengthening. A scale transition model based on the iso-work assumption and describing the macroscopic tensile behavior of the material depending on the individual mechanical behavior of each phase is also proposed. This model enables to provide insights into the underlying deformation and work-hardening mechanisms.

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Section: U N C O R R E C T E D P R O O Fmentioning

confidence: 99%

Section: U N C O R R E C T E D P R O O Fmentioning

confidence: 99%

Micromechanical behavior and thermal stability of a dual-phase α+α’ titanium alloy produced by additive manufacturing

et al. 2019

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“…Thermal treatments have no effect when it comes to resolving the issue of residual porosities in A.M. components . Hot Isostatic Pressing (HIP), that combines an increase in temperature with the application of an isostatic pressure, has long been used as a post‐processing treatment to heal porosities in parts produced by conventional powder metallurgy . Although it might induce some microstructural coarsening thus decreasing static tensile strength, HIP has already been successfully applied to improve the fatigue life of metallic A.M. parts.…”

Section: Post‐processingmentioning

confidence: 99%

Fusion‐Based Additive Manufacturing for Processing Aluminum Alloys: State‐of‐the‐Art and Challenges

2017

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The fusion-based additive manufacturing of Al alloys has been developing at an ever faster pace since early 2015, after a comparatively slow start with respect to other metallic materials. This paper reviews the recent developments with the aim of identifying challenges and opportunities for future work. Additive Al components possess strongly out-of-equilibrium microstructures resulting in potentially enhanced mechanical properties. A deeper understanding of the thermal history during fabrication, the design of new high strength alloys and the development of better adapted post-processing procedures are still needed to take full advantages of the specificities of additive manufacturing.

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“…13 It is well documented that porosity can result in fatigue crack initiation. 5,10,[14][15][16][17][18][19][20] In the work presented herein, the critical size of the pores that are prone to fatigue cracks is investigated and quantified for Inconel 718 material produced by SLM.…”

Section: Introductionmentioning

confidence: 99%

ICME Approach to Determining Critical Pore Size of IN718 Produced by Selective Laser Melting

Sangid

Ravi

Prithivirajan

et al. 2019

JOM

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A degree of porosity is expected in additively manufactured (AM) materials. To aid in the qualification of AM materials, the smallest pore size that results in a debit in the fatigue performance is quantified. In the work presented herein, crystal plasticity simulations are used to identify the stress concentration around pores of various sizes, revealing that a single 20-lm pore or two 10-lm pores (with centers spaced 15 lm apart) localize stress at the pore, as opposed to elsewhere in the microstructure. In situ microtomography and far-field high-energy x-ray diffraction microscopy were used to identify crack formation and the evolution of the grain-level micromechanical fields during cyclic loading. Eighteen cracks were observed (15 at pores, 3 at the surface) at highly stressed grains in a sample, although most did not propagate. The dominant crack was seen to originate from the free surface, which is rationalized by fracture mechanics.

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Effects of post-processing on cyclic fatigue response of a titanium alloy additively manufactured by electron beam melting

Cited by 95 publications

References 33 publications

Micromechanical behavior and thermal stability of a dual-phase α+α’ titanium alloy produced by additive manufacturing

Micromechanical behavior and thermal stability of a dual-phase α+α’ titanium alloy produced by additive manufacturing

Fusion‐Based Additive Manufacturing for Processing Aluminum Alloys: State‐of‐the‐Art and Challenges

ICME Approach to Determining Critical Pore Size of IN718 Produced by Selective Laser Melting

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