Defect-based characterization of the fatigue behavior of additively manufactured titanium aluminides

Teschke, Mirko; Moritz, Juliane; Tenkamp, Jochen; Marquardt, Axel; Leyens, Christoph; Walther, Frank

doi:10.1016/j.ijfatigue.2022.107047

Cited by 17 publications

(19 citation statements)

References 61 publications

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“…The Shiozawa diagram is corrected for the defect size; therefore, it was able to decrease the scattering in the Woehler diagram that was generated from the different defect sizes. This can be observed where the coefficient of determination improved for AlSi10Mg from R 2 = 0.66 in the (Tenkamp et al, 2022), 316L (Kotzem et al, 2021), and TNM-B1 (Teschke et al, 2022) Woehler curve to R 2 = 0.81 in the Shiozawa curve. R 2 improved to 0.94 and 0.72 for 316L and TNM-B1, respectively.…”

Section: Fatigue Testing Resultsmentioning

confidence: 84%

“…It is also obtained from the specific Woehler curve that the lightweight potential for TNM-B1 has the highest value, followed by 316L and AlSi10Mg. Comparing Woehler and Shiozawa curves, it is concluded that the defect size (a i ) introduced by Murakami is particularly suitable for the geometric description of the (Tenkamp et al, 2022), 316L (Kotzem et al, 2021;Stern et al, 2022), and TNM-B1 (Teschke et al, 2022) defect as an initial defect or crack size, while the model presented by Shiozawa takes this influence into account and enables a "defect-based" representation of the fatigue behavior. Therefore, the Shiozawa diagram improves the fatigue assessment of defective materials as it enables a fatigue defect or tolerant assessment.…”

Section: Discussionmentioning

confidence: 99%

“…This allowed the investigation of two microstructurally comparable states with a variation in defect type and size. Detailed information about the manufacturing process can be found in the studies by Moritz et al, (2021); Teschke et al, (2022). AlSi10Mg specimens were manufactured vertically, parallel to the building direction.…”

Section: Methodsmentioning

confidence: 99%

“…All specimens were tested at room temperature (RT). More detailed information about the micro-structure and tensile testing results can be found in the studies by Kotzem et al, (2021); Tenkamp et al, (2022); Teschke et al, (2022).…”

Section: Methodsmentioning

confidence: 99%

“…FIGURE 1 | (A) Vickers hardness. (B) Fractographic analyses for AlSi10Mg(Tenkamp et al, 2022), 316L(Kotzem et al, 2021), and TNM-B1(Teschke et al, 2022) …”

mentioning

confidence: 99%

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Assessing the Lightweight Potential of Additively Manufactured Metals by Density-Specific Woehler and Shiozawa Diagrams

et al. 2022

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Additive manufacturing (AM) using the powder bed fusion (PBF) process is building up the components layer by layer, which enables the fabrication of complex 3D structures with unprecedented degrees of freedom. Due to the high cooling rates of the AM process, fine microstructures are generated. This leads to an improvement in quasistatic properties such as tensile strength, whereas the fatigue strength is comparable to that of conventionally manufactured metal or even reduced. This is due to the presence of process-induced defects formulated during the manufacturing process in combination with the increased notch stress sensitivity of high-strength metals. In this work, the fatigue damage assessment using different approaches like those of Murakami and Shiozawa for three AM alloys (AlSi10Mg, 316L, and TNM-B1) containing defects is studied for better understanding of capability and mechanisms. Moreover, the effect of the lightweight potential is investigated, and how the specific material density can be considered when the fatigue damage tolerance is characterized.

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Section: Fatigue Testing Resultsmentioning

confidence: 84%

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

“…FIGURE 1 | (A) Vickers hardness. (B) Fractographic analyses for AlSi10Mg(Tenkamp et al, 2022), 316L(Kotzem et al, 2021), and TNM-B1(Teschke et al, 2022) …”

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confidence: 99%

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Assessing the Lightweight Potential of Additively Manufactured Metals by Density-Specific Woehler and Shiozawa Diagrams

et al. 2022

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Locally Adapted Microstructures in an Additively Manufactured Titanium Aluminide Alloy Through Process Parameter Variation and Heat Treatment

et al. 2022

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Electron beam powder bed fusion (PBF-EB/M) has been attracting great research interest as a promising technology for additive manufacturing of titanium aluminide alloys. However, challenges often arise from the processinduced evaporation of aluminum, which is linked to the PBF-EB/M process parameters. This study applies different volumetric energy densities during PBF-EB/M processing to deliberately adjust the aluminum contents in additively manufactured Ti-43.5Al-4Nb-1Mo-0.1B (TNM-B1) samples. The specimens are subsequently subjected to hot isostatic pressing (HIP) and a two-step heat treatment. The influence of process parameter variation and heat treatments on microstructure and defect distribution are investigated using optical and scanning electron microscopy, as well as X-ray computed tomography (CT). Depending on the aluminum content, shifts in the phase transition temperatures can be identified via differential scanning calorimetry (DSC). It is confirmed that the microstructure after heat treatment is strongly linked to the PBF-EB/M parameters and the associated aluminum evaporation. The feasibility of producing locally adapted microstructures within one component through process parameter variation and subsequent heat treatment can be demonstrated. Thus, fully lamellar and nearly lamellar microstructures in two adjacent component areas can be adjusted, respectively.

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Influence of Two‐Step Heat Treatments on Microstructure and Mechanical Properties of a β‐Solidifying Titanium Aluminide Alloy Fabricated via Electron Beam Powder Bed Fusion

et al. 2022

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Additive manufacturing technologies, particularly electron beam powder bed fusion (PBF‐EB/M), are becoming increasingly important for the processing of intermetallic titanium aluminides. This study presents the effects of hot isostatic pressing (HIP) and subsequent two‐step heat treatments on the microstructure and mechanical properties of the TNM‐B1 alloy (Ti–43.5Al–4Nb–1Mo–0.1B) fabricated via PBF‐EB/M. Adequate solution heat treatment temperatures allow the adjustment of fully lamellar (FL) and nearly lamellar (NL‐β) microstructures. The specimens are characterized by optical microscopy and scanning electron microscopy (SEM), X‐ray computed tomography (CT), X‐ray diffraction (XRD), and electron backscatter diffraction (EBSD). The mechanical properties at ambient temperatures are evaluated via tensile testing and subsequent fractography. While lack‐of‐fusion defects are the main causes of failure in the as‐built condition, the mechanical properties in the heat‐treated conditions are predominantly controlled by the microstructure. The highest ultimate tensile strength is achieved after HIP due to the elimination of lack‐of‐fusion defects. The results reveal challenges originating from the PBF‐EB/M process, for example, local variations in chemical composition due to aluminum evaporation, which in turn affect the microstructures after heat treatment. For designing suitable heat treatment strategies, particular attention should therefore be paid to the microstructural characteristics associated with additive manufacturing.

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Defect-based characterization of the fatigue behavior of additively manufactured titanium aluminides

Cited by 17 publications

References 61 publications

Assessing the Lightweight Potential of Additively Manufactured Metals by Density-Specific Woehler and Shiozawa Diagrams

Assessing the Lightweight Potential of Additively Manufactured Metals by Density-Specific Woehler and Shiozawa Diagrams

Locally Adapted Microstructures in an Additively Manufactured Titanium Aluminide Alloy Through Process Parameter Variation and Heat Treatment

Influence of Two‐Step Heat Treatments on Microstructure and Mechanical Properties of a β‐Solidifying Titanium Aluminide Alloy Fabricated via Electron Beam Powder Bed Fusion

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