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About: Inconel is a(n) research topic. Over the lifetime, 4935 publication(s) have been published within this topic receiving 75447 citation(s). more

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Journal ArticleDOI
Krista Amato1, Sara M. Gaytan1, Lawrence E Murr1, E. Martinez1  +4 moreInstitutions (1)
01 Mar 2012-Acta Materialia
Abstract: In this study Inconel 718 cylinders were fabricated by selective laser melting in either argon or nitrogen gas from a pre-alloyed powder. As-fabricated cylinders oriented in the build direction (z-axis) and perpendicular to the build direction (x-axis) exhibited columnar grains and arrays of γ″ (body-centered tetragonal) Ni3Nb oblate ellipsoidal precipitates oriented in a strong [2 0 0] texture determined by combined optical metallography, transmission electron microscopy, and X-ray diffraction analysis. Fabricated and hot isostatic pressed (HIP) components exhibited a more pronounced [2 0 0] columnar γ″ phase precipitate architecture parallel to the laser beam or build direction (spaced at ∼0.8 μm), and a partially recrystallized fcc grain structure. Fabricated and annealed (1160 °C for 4 h) components were ∼50% recrystallized and the recrystallized regions contained spheroidal γ′ precipitates distributed in a dense field of fine γ″ precipitates. The γ″ precipitates were always observed to be coincident with {1 0 0} planes of the γ-fcc NiCr matrix. Some δ phase precipitates in the unrecrystallized/recrystallized interfaces and recrystallized grain boundaries were also observed in the annealed samples. The microindentation (Vickers) hardness was 3.9 GPa for the as-fabricated materials, 5.7 GPa for the HIP material, and 4.6 GPa for the annealed material. Corresponding tensile properties were comparable with wrought Inconel 718 alloy. more

677 citations

Journal ArticleDOI
Qingbo Jia1, Dongdong Gu1Institutions (1)
Abstract: This paper presented a comprehensive study of densification behavior, microstructural features, microhardness, wear performance and high-temperature oxidation properties of Inconel 718 parts fabricated by selective laser melting (SLM), a typical additive manufacturing process. The relationship of processing conditions, microstructures and material properties was established. The occurrence of balling phenomenon at a lower laser energy density input reduced the relative density of the formed parts. A reasonable increase in laser energy density yielded a near-full densification. The typical microstructures of SLM-processed Inconel 718 parts experienced successive morphological changes on increasing the applied laser energy density: coarsened columnar dendrites – clustered dendrites – slender and uniformly distributed columnar dendrites. The optimally prepared fully dense Inconel 718 parts had a uniform microhardness distribution with a mean value of 395.8 HV 0.2 , a considerably low friction coefficient of 0.36 and a reduced wear rate of 4.64 × 10 −4 mm 3 /N m in sliding wear tests. The formation of an adherent tribolayer on the worn surface contributed to the improvement of wear performance. The high-temperature oxidation resistance was enhanced as the applied laser energy density increased and the elevated high-temperature oxidation property was primarily attributed to the formation of refined microstructural architectures of SLM-processed parts. more

501 citations

Journal ArticleDOI
Abstract: Nickel-base super alloys (Inconel) are generally known to be one of the most difficult materials to machine because of their high hardness, high strength at high temperature, affinity to react with the tool materials, and low thermal diffusivity. This paper presents a general review of their material characteristics and properties together with their machinability assessment when using different cutting tools. The advantages and disadvantages of different tool materials with regard to the machining Inconel are highlighted. more

476 citations

Journal ArticleDOI
01 Jan 1997-Wear
Abstract: The present paper deals with the high-speed machining of Inconel 718 and Ti6Al6V2Sn alloys from a thermal point of view. Temperature and wear of cutting tools are investigated by means of cutting experiments and numerical analysis up to a cutting speed of around 600 m min−1. For Inconel 718, severe wear of ceramic tools, particularly highly developed boundary notch wear, is correlated with variation of the chip formation mechanism from continuous,to discontinuous, which is accompanied by large side flow of the chip and plastic burrs of the workpiece. This indicates that the wear is developed by an abrasive process rather than by a thermally activated mechanism. A TlC-added alumina tool is superior to silicon nitride across a speed range from 250 to 500 m min−1, where the cutting temperature exceeds 1200°C. In end milling of the titanium alloy, high-speed machining up to a cutting speed of 628 m min−1 (20 000 r.p.m.) is possible for sintered carbide tools. Measurements of cutting temperature during intermittent turning of a titanium disk, which is modelled on milling, reveal that the feasibility of high-speed end milling depends on a transient temperature rise or ‘time-lag’, owing to a short cut distance of the tool edge per single revolution, the existence of the helix angle, and a temperature drop through the use of a coolant. These factors contribute to the reduction of tool temperature. Finally, a numerical model is proposed to validate the temperature measurement. more

460 citations

Journal ArticleDOI
Abstract: The microstructural and mechanical properties of Inconel 718 were determined on the specimens manufactured by selective laser melting (SLM) of prealloyed powder. High- density (99.8%) cylindrical specimens were built with four orientations (0°, 45°, 45°×45° and 90°) in relation to the building and scanning directions. Because of directional, dendritic-cellular grain growth, microstructure of the as-built specimens was characterized by columnar grains of supersaturated solid solution with internal microsegregation of Nb and Mo, demonstrated by fractions of Laves eutectic or its divorced form in interdendritic regions. Such a heterogeneous microstructure is unsuitable for direct post-process aging and makes the alloy sensitive to subsolidus liquation during rapid heating to the homogenizing temperature. In homogenized and aged condition, the alloy received a very good set of mechanical properties in comparison with the wrought material. In heat-treated condition, like in as-built condition, weak anisotropy of properties was found, manifested by lower Young's modulus, yield strength and tensile strength of the specimens extended along the build direction in comparison to the values for the other variants of the specimens. This is attributed to the fact that the grains maintained their geometric and crystallographic texture obtained during solidification. more

359 citations

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Topic's top 5 most impactful authors

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