Additive Manufacturing of Nickel Superalloys: Opportunities for Innovation and Challenges Related to Qualification

Babu, S. S.; Raghavan, Narendran; Raplee, J.; Foster, Samuel; Frederick, Clayton; Haines, M.; Dinwiddie, Ralph B.; Kirka, M. K.; Plotkowski, Alex; Lee, Yousub; Dehoff, Ryan R.

doi:10.1007/s11661-018-4702-4

Cited by 160 publications

(62 citation statements)

References 93 publications

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“…The ultimate tensile strength (UTS) and elongation at failure was high with both Z samples with the tensile axis oriented along the build direction (EBM, SLM) and XY samples with the tensile axis oriented normal to the build direction (SLM), demonstrating good properties both parallel and transverse to the axis of the columnar microstructure. In spite of their high UTS after significant strain-hardening during plastic flow, tensile ductilities in excess of 32% are observed for EBM SB-CoNi-10, which is higher compared to the standard precipitation strengthened Nibase alloy CM 247 Ⓡ (CM 247 Ⓡ is a registered trademark of Cannon-Muskegon Corporation) fabricated by EBM 33 . For the SLM SB-CoNi-10 specimens, tensile ductilities in excess of 13% are observed, which is again greater than the standard precipitation strengthened Ni-base alloy IN738LC manufactured by SLM 57 .…”

Section: Discussionmentioning

confidence: 95%

A defect-resistant Co–Ni superalloy for 3D printing

et al. 2020

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Additive manufacturing promises a major transformation of the production of high economic value metallic materials, enabling innovative, geometrically complex designs with minimal material waste. The overarching challenge is to design alloys that are compatible with the unique additive processing conditions while maintaining material properties sufficient for the challenging environments encountered in energy, space, and nuclear applications. Here we describe a class of high strength, defect-resistant 3D printable superalloys containing approximately equal parts of Co and Ni along with Al, Cr, Ta and W that possess strengths in excess of 1.1 GPa in as-printed and post-processed forms and tensile ductilities of greater than 13% at room temperature. These alloys are amenable to crack-free 3D printing via electron beam melting (EBM) with preheat as well as selective laser melting (SLM) with limited preheat. Alloy design principles are described along with the structure and properties of EBM and SLM CoNi-base materials.

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Section: Discussionmentioning

confidence: 95%

A defect-resistant Co–Ni superalloy for 3D printing

et al. 2020

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“…In recent years, compared with conventional manufacturing methods, additive manufacturing (AM) of nickel-based super Alloy 718 s has attracted considerable attention in aerospace and power generation applications [1] . In AM, a certain part is manufactured using a layer-bylayer approach using a 3D-digital model of the part.…”

Section: Introductionmentioning

confidence: 99%

Toward a Better Understanding of Phase Transformations in Additive Manufacturing of Alloy 718

et al. 2020

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This paper presents a discussion on the phase-transformation aspects of additively manufactured Alloy 718 during the additive manufacturing (AM) process and subsequent commonly used post-heat treatments. To this end, fundamental theoretical principles, thermodynamic and kinetics modeling, and existing literature data are employed. Two different AM processes, namely, laser-directed energy deposition and electron-beam powder-bed fusion are considered. The general aspects of phase formation during solidification and solid state in Alloy 718 are first examined, followed by a detailed discussion on phase transformations during the two processes and subsequent standard post heat-treatments. The effect of cooling rates, thermal gradients, and thermal cycling on the phase transformation in Alloy 718 during the AM processes are considered. Special attention is given to illustrate how the segregated composition during the solidification could affect the phase transformations in the Alloy 718. The information provided in this study will contribute to a better understanding of the overall process-structure-property relationship in the AM of Alloy 718 718.

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“…The versatile 3D‐printing technique emerging in recent years appears to be a powerful route toward this goal 3. Via “epitaxial” deposition of the alloy, one layer at a time, additive manufacturing can preserve the crystallographic orientation of the substrate single crystal 4–11.…”

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confidence: 99%

Rafting‐Enabled Recovery Avoids Recrystallization in 3D‐Printing‐Repaired Single‐Crystal Superalloys

Chen

Huang

et al. 2020

Advanced Materials

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The repair of damaged Ni‐based superalloy single‐crystal turbine blades has been a long‐standing challenge. Additive manufacturing by an electron beam is promising to this end, but there is a formidable obstacle: either the residual stress and γ/γ ′ microstructure in the single‐crystalline fusion zone after e‐beam melting are unacceptable (e.g., prone to cracking), or, after solutionizing heat treatment, recrystallization occurs, bringing forth new grains that degrade the high‐temperature creep properties. Here, a post‐3D printing recovery protocol is designed that eliminates the driving force for recrystallization, namely, the stored energy associated with the high retained dislocation density, prior to standard solution treatment and aging. The post‐electron‐beam‐melting, pre‐solutionizing recovery via sub‐solvus annealing is rendered possible by the rafting (i.e., directional coarsening) of γ ′ particles that facilitates dislocation rearrangement and annihilation. The rafted microstructure is removed in subsequent solution treatment, leaving behind a damage‐free and residual‐stress‐free single crystal with uniform γ ′ precipitates indistinguishable from the rest of the turbine blade. This discovery offers a practical means to keep 3D‐printed single crystals from cracking due to unrelieved residual stress, or stress‐relieved but recrystallizing into a polycrystalline microstructure, paving the way for additive manufacturing to repair, restore, and reshape any superalloy single‐crystal product.

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Additive Manufacturing of Nickel Superalloys: Opportunities for Innovation and Challenges Related to Qualification

Cited by 160 publications

References 93 publications

A defect-resistant Co–Ni superalloy for 3D printing

A defect-resistant Co–Ni superalloy for 3D printing

Toward a Better Understanding of Phase Transformations in Additive Manufacturing of Alloy 718

Rafting‐Enabled Recovery Avoids Recrystallization in 3D‐Printing‐Repaired Single‐Crystal Superalloys

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