Bimodal grain structures and tensile properties of a biomedical Co–20Cr–15W–10Ni alloy with different pre-strains

Li, Cheng Lin; Choi, Sunwoong; Oh, Jeong Mok; Hong, Jae‐Keun; Yeom, Jong‐Taek; Kang, Joo‐Hee; Mei, Q.S.; Park, Chan Hee

doi:10.1007/s12598-020-01566-3

Cited by 19 publications

(7 citation statements)

References 48 publications

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“…Thickness losses of treated samples calculated from Equation (1) versus immersion time are shown in Figure 5. The thickness loss of the untreated sample approximately follows a linear law with immersion time, which is consistent to the results reported by Tang et al [11,12] that the thickness loss of bare Co-Cr-Mo alloy is mainly controlled by the dissolution of the (Co, Cr, Mo)2Al9 intermetallic layer into molten Al. In contrast, the thicknesses of treated samples remained constant for a given period.…”

Section: Resultssupporting

confidence: 91%

“…Figure 7a-c display the typical interfacial structures for the untreated sample immersed for 3 min and the 24 h-treated sample immersed 3 h (stage II) and 5 h (stage III), respectively. For the untreated sample, two layers of reactants were observed: an intermetallic layer ① of (Co, Cr, Mo)2Al9 attached closely to the alloy matrix, and a multiphase layer ② between the intermetallic layer and Al [11,12]. The intermetallic layer possessed a clear and smooth interface with the alloy matrix but an uneven interface with the multiphase layer.…”

Section: Resultsmentioning

confidence: 99%

“…Although the reaction is significantly less severe compared to that of tool steels, bare Co-29Cr-6Mo (Co-Cr-Mo) alloy is still gradually corroded under molten Al, leading to the local failure of the alloy due to the formation of intermetallic compounds between the matrix and molten Al [9][10][11][12][13]. In light of this, various methods-including nitriding [14], oxidation treatment [10], and alloying Si [9,15], Al, Ti, and Zr [16]-have been adopted to improve the corrosion resistance of Co-Cr-Mo alloy to molten Al.…”

Section: Introductionmentioning

confidence: 99%

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Enhanced Anti-Corrosion Performance of Co-Cr-Mo Alloy in Molten Al by Prior Oxidation Treatment

Shang,

Yang,

2023

Materials

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Co-based alloys are promising alternatives to replace the currently used tool steels in aluminum die-casting molds for producing sophisticated products. Although the reaction is significantly less severe compared to that of tool steels, bare Co-29Cr-6Mo (CCM) alloy is still gradually corroded under molten Al, leading to the local failure of the alloy due to the formation of intermetallic compounds between the matrix and molten Al. This study indicated that prior oxidation treatment at 750 °C on CCM alloy is beneficial in enhancing the corrosion resistance of the alloy to molten Al. The is more pronounced in the alloy after a longer oxidation treatment. However, after oxidation for longer than 24 h, the protectiveness of the film cannot be enhanced anymore. In addition, even after the full failure of the oxide film, the thickness loss rate of a sample with prior oxidation treatment is much lower than that of a bare sample. This can be attributed to the fact that network-aligned oxide particles of the cone structure boundary inhibit both the outwards movements of alloying elements and the dissolution of the intermetallic layer.

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Section: Resultssupporting

confidence: 91%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Enhanced Anti-Corrosion Performance of Co-Cr-Mo Alloy in Molten Al by Prior Oxidation Treatment

Shang,

Yang,

2023

Materials

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“…Because microstructural evolution such as grain size change, [2,7,8] precipitate formation, [5,[9][10][11][12][13] and phase transformation [14][15][16] occur in CCWN alloys during thermomechanical treatment, it is essential to understand the role of microstructural evolution in improving the mechanical properties of the alloys through microstructural control. [15,[17][18][19][20][21][22][23][24] Ueki et al [17] designed alloys that can achieve high ductility by low-temperature heat treatment (LTHT) at 873 K in addition to high strength by grain refinement via static recrystallization. Improvement of ductility by LTHT has also been reported in biomedical Co-27Cr-6Mo alloys (mass pct).…”

Section: Introductionmentioning

confidence: 99%

“…Improvement of ductility by LTHT has also been reported in biomedical Co-27Cr-6Mo alloys (mass pct). [25] Li et al [19][20][21][22][23] achieved high strength in CCWN alloys through the formation of a bimodal grain structure. Moreover, they reported that a bimodal grain structure can be formed by performing cold rolling and static recrystallization five times, resulting in high strength and high ductility.…”

Section: Introductionmentioning

confidence: 99%

Development of Low-Yield Stress Co–Cr–W–Ni Alloy by Adding 6 Mass Pct Mn for Balloon-Expandable Stents

Yanagihara

Ueki

Ueda

et al. 2021

Metall Mater Trans A

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This is the first report presenting the development of a Co–Cr–W–Ni–Mn alloy by adding 6 mass pct Mn to ASTM F90 Co–20Cr–15W–10Ni (CCWN, mass pct) alloy for use as balloon-expandable stents with an excellent balance of mechanical properties and corrosion resistance. The effects of Mn addition on the microstructures as well as the mechanical and corrosion properties were investigated after hot forging, solution treatment, swaging, and static recrystallization. The Mn-added alloy with a grain size of ~ 20 µm (recrystallization condition: 1523 K, 150 seconds) exhibited an ultimate tensile strength of 1131 MPa, 0.2 pct proof stress of 535 MPa, and plastic elongation of 66 pct. Additionally, it exhibited higher ductility and lower yield stress while maintaining high strength compared to the ASTM F90 CCWN alloy. The formation of intersecting stacking faults was suppressed by increasing the stacking fault energy (SFE) with Mn addition, resulting in a lower yield stress. The low-yield stress is effective in suppressing stent recoil. In addition, strain-induced martensitic transformation during plastic deformation was suppressed by increasing the SFE, thereby improving the ductility. The Mn-added alloys also exhibited good corrosion resistance, similar to the ASTM F90 CCWN alloy. Mn-added Co–Cr–W–Ni alloys are suitable for use as balloon-expandable stents.

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Tailoring Microstructure and Mechanical Properties of Additively Manufactured Inconel 625 by Remelting Strategy in Laser Powder Bed Fusion

Ledwig,

Pasiowiec,

Cichocki

et al. 2024

Metall Mater Trans A

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This study investigates the effect of laser power applied for a remelting scan in the laser powder bed fusion process on the formation of a bimodal microstructure and its impact on the mechanical properties of Ni-based Inconel 625 superalloy. Comparison of primary and remelting scans at similar surface energy densities revealed that the melt pools obtained in the remelting scan are smaller than in the primary scan. To achieve comparable remelted melt pool sizes, the 25 pct increase in energy is required. The shape and size of the remelted melt pools significantly affect the microstructure and material texture. The lower surface energy density in laser powder bed fusion favors the formation of a bimodal microstructure with large columnar grains and fine grain bands. Application of higher energy results in the formation of large columnar grains with Goss texture along build direction and separated by a large amount of low angle grain boundaries. Remelting scan also affects reduction of porosity and increasing of the area fraction of nanometric oxide inclusions. The study revealed that the samples subjected to a remelting laser scan and tensile tested along the direction of columnar grains exhibited higher ductility, which was associated with a slight decrease in the ultimate tensile strength compared to the samples that were not remelted. It was demonstrated that the remelting scan in the laser powder bed fusion process offers the possibility of improving the reliability of additively manufactured Inconel 625 superalloy by reducing porosity and tailoring its microstructure towards single-crystal-like, and thus improving the mechanical properties. Graphical Abstract

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Bimodal grain structures and tensile properties of a biomedical Co–20Cr–15W–10Ni alloy with different pre-strains

Cited by 19 publications

References 48 publications

Enhanced Anti-Corrosion Performance of Co-Cr-Mo Alloy in Molten Al by Prior Oxidation Treatment

Enhanced Anti-Corrosion Performance of Co-Cr-Mo Alloy in Molten Al by Prior Oxidation Treatment

Development of Low-Yield Stress Co–Cr–W–Ni Alloy by Adding 6 Mass Pct Mn for Balloon-Expandable Stents

Tailoring Microstructure and Mechanical Properties of Additively Manufactured Inconel 625 by Remelting Strategy in Laser Powder Bed Fusion

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