Short-term creep behavior of an additive manufactured non-weldable Nickel-base superalloy evaluated by slow strain rate testing

Xu, Jinghao; Gruber, Hans; Deng, Dewei; Peng, Ru Lin; Moverare, Johan

doi:10.1016/j.actamat.2019.08.034

Cited by 90 publications

(15 citation statements)

References 66 publications

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“…Generally, the static recrystallization temperature of the nickel-base superalloy is in the range of 1000-1100 °C and under this temperature range, recrystallization will gradually take place [83]. However, according to extensive investigations, for example, Kunze et al [25] reported that the as-laser deposited IN738LC superalloy retains the strong cubic texture although it went through a super-solvus hot isostatic pressing (HIP) at 1180 °C for 4 h. Similarly, in the previous study on LPBF IN738LC superalloy [84], a combination of thermal treatments including 1210 °C HIP for 4 h plus 2-h solutioning at 1120 °C and 24-h aging at 850 °C failed to bring a fully recrystallized microstructure. Moreover, to eliminate the crystallographic texture induced by LPBF in IN738LC, Geiger et al [85] applied a full heat treatment including a super-solvus heat treatment at 1250 °C for 3 h followed by a 1200 °C HIP for 4 h, and 1120 °C solution treatment for 2 h, and a 20 h aging at 850 °C.…”

Section: Sluggish Recrystallizationmentioning

confidence: 88%

“…In this work, the Scheil solidification model was used, where no diffusion was assumed in the formed solid phases while the diffusion was assumed to be infinitely fast in the remaining liquid phases. Taken the IN738LC superalloy as an example, the Scheil solidification freezing range is determined by thermodynamic calculation (ThermoCalc, TTNI8 database) to be 239 K [84]. Therefore, the localized solidification process is supposed to be accomplished within 3×10 -4 s, thus, is estimated to be 3×10 -4 s. For the major elements in IN738LC superalloy, the Nb shows fast diffusion rate [158].…”

Section: Segregation Behavior In Lpbfmentioning

confidence: 99%

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Alloy Design and Characterization of γ′ Strengthened Nickel-based Superalloys for Additive Manufacturing

2021

Linköping Studies in Science and Technology. Licentiate Thesis

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Nickel-based superalloys, an alloy system bases on nickel as the matrix element with the addition of up to 10 more alloying elements including chromium, aluminum, cobalt, tungsten, molybdenum, titanium, and so on. Through the development and improvement of nickel-based superalloys in the past century, they are well proved to show excellent performance at the elevated service temperature. Owing to the combination of extraordinary high-temperature mechanical properties, such as monotonic and cyclic deformation resistance, fatigue crack propagation resistance; and high-temperature chemical properties, such as corrosion and oxidation resistance, phase stability, nickel-based superalloys are widely used in the critical hot-section components in aerospace and energy generation industries. The success of nickel-based superalloy systems attributes to both the well-tailored microstructures with the assistance of carefully doped alloying elements, and the intently developed manufacturing processes. The microstructure of the modern nickel-based superalloys consists of a two-phase configuration: the intermetallic precipitates (Ni,Co)3(Al,Ti,Ta) known as γ′ phase dispersed into the austenite γ matrix, which is firstly introduced in the 1940s. The recently developed additive manufacturing (AM) techniques, acting as the disruptive manufacturing process, offers a new avenue for producing the nickel-based superalloy components with complicated geometries. However, γ′ strengthened nickel-based superalloys always suffer from the micro-cracking during the AM process, which is barely eliminated by the process optimization. On this basis, the new compositions of γ′ strengthened nickel-based superalloy adapted to the AM process are of great interest and significance. This study sought to design novel γ′ strengthened nickel-based superalloys readily for AM process with limited cracking susceptibility, based on the understanding of the cracking mechanisms. A two-parameter model is developed to predict the additive manufacturability for any given composition of a nickel-based superalloy. One materials index is derived from the comparison of the deformation-resistant capacity between dendritic and interdendritic regions, while another index is derived from the difference of heat resistant capacity of these two spaces. By plotting the additive manufacturability diagram, the superalloys family can be categorized into the easy-to-weld, fairly-weldable, and non-weldable regime with the good agreement of the existed knowledge. To design a novel superalloy, a Cr-Co-MoW -Al-Ti-Ta-Nb-Fe-Ni alloy family is proposed containing 921,600 composition recipes in total. Through the examination of additive manufacturability, undesired phase formation propensity, and the precipitation fraction, one composition of superalloy, MAD542, out of the 921,600 candidates is selected. Validation of additive manufacturability of MAD542 is carried out by laser powder bed fusion (LPBF). By optimizing the LPBF process parameters, the crack-free MAD542 part is achieved. I...

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Section: Sluggish Recrystallizationmentioning

confidence: 88%

Section: Segregation Behavior In Lpbfmentioning

confidence: 99%

Alloy Design and Characterization of γ′ Strengthened Nickel-based Superalloys for Additive Manufacturing

2021

Linköping Studies in Science and Technology. Licentiate Thesis

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“…In general, the mechanisms for GB-mediated plasticity are GB sliding and grain rotation [65] . Indeed, in our previous study [66] , GB sliding could substitute as the dominant deformation accommodation mechanism in L -PBF IN738LC superalloys at the elevated temperature and under slow strain rate conditions. However, it has been proposed that the GB-mediated plasticity at relatively low temperature requires that the grain size is reduced to a critical value, e.g.…”

Section: On the Conflicting Nature Of Strengthening And Ductility Reductionmentioning

confidence: 83%

On the Strengthening and Embrittlement Mechanisms of an Additively Manufactured Nickel-Base Superalloy

Gruber

Boyd

et al. 2020

SSRN Journal

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The ′ phase strengthened Nickel-base superalloy is one of the most significant dual-phase alloy systems for hightemperature engineering applications. The tensile properties of laser powder-bed-fused IN738LC superalloy in the as-built state have been shown to have both good strength and ductility compared with its post-thermal treated state. A microstructural hierarchy composed of weak texture, sub-micron cellular structures and dislocation cellular walls was promoted in the as-built sample. After post-thermal treatment, the secondary phase ′ precipitated with various size and fraction depending on heat treatment process. For room-temperature tensile tests, the dominated deformation mechanism is planar slip of dislocations in the as-built sample while dislocations bypassing the precipitates via Orowan looping in the ′ strengthened samples. The extraordinary strengthening effect due to the dislocation substructure in the as-built sample provides an addition of 372 MPa in yield strength. The results of our calculation are in agreement with experimental yield strength for all the three different conditions investigated. Strikingly, the ′ strengthened samples have higher work hardening rate than as-built sample but encounter premature failure. Experimental evidence shows that the embrittlement mechanism in the ′ strengthened samples is caused by the high dislocation hardening of the grain interior region, which reduces the ability to accommodate further plastic strain and leads to premature intergranular cracking. On the basis of these results, the strengthening micromechanism and double-edge effect of strength and ductility of Nickel-base superalloy is discussed in detail.

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“…Although there are many potential benefits to this manufacturing process, many questions still exist regarding its use for high temperature applications. Most recent research has focused on the room temperature and high temperature time independent mechanical properties, with limited research on time-dependent properties [5][6][7]. The focus of this study was to evaluate the microstructural and high temperature time dependent mechanical properties of an additively manufactured nickel base super alloy.…”

Section: Introductionmentioning

confidence: 99%

Metallurgical Evaluation of an Additively Manufactured Nickel-Base Superalloy for Gas Turbine Guide Vanes

Bridges

Shingledecker

Torkaman³

et al. 2020

Volume 8: Industrial and Cogeneration; Manufacturing Materials and Metallurgy; Marine; Microturbines, Turbochargers, and Small

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In this paper, AM produced test samples of a IN939 derivative nickel-based alloy were tested for tensile, fatigue and creep properties at temperatures up to 871°C and compared to the traditional cast material. Initial results showed improved tensile and fatigue strength, but a reduction in both long-term creep rupture strength and creep ductility in the AM produced material compared to the cast baseline. Microstructural observations in the AM produced material showed a significant difference in the overall metallurgical characteristics beyond grain size compared to the castings. In addition to the laboratory studies and to provide a direct comparison between AM and traditional castings, both AM and cast components were tested in live engine trials exceeding 4,000 hours. Detailed scanning electron microscopy techniques were used to evaluate the evolution of grain size, gamma-prime, MC carbide and secondary M23C6 carbide size and distribution throughout a 5-step heat treatment process. Post-test evaluations for creep rupture specimens of the AM material showed creep cavitation near grain boundaries. The results from the AM produced material are discussed in comparison to expected properties and characteristics from traditional casting methods. Results have shown that material production and short-term metallurgical properties are sufficient to produce quality high temperature stationary guide vanes, but additional research and development is needed to optimize the AM process to achieve high-temperature creep behavior comparable to castings.

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Short-term creep behavior of an additive manufactured non-weldable Nickel-base superalloy evaluated by slow strain rate testing

Cited by 90 publications

References 66 publications

Alloy Design and Characterization of γ′ Strengthened Nickel-based Superalloys for Additive Manufacturing

Alloy Design and Characterization of γ′ Strengthened Nickel-based Superalloys for Additive Manufacturing

On the Strengthening and Embrittlement Mechanisms of an Additively Manufactured Nickel-Base Superalloy

Metallurgical Evaluation of an Additively Manufactured Nickel-Base Superalloy for Gas Turbine Guide Vanes

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