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Showing 1 to 17 of 17 for “"Nickel-base superalloys"”.
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Banding in nickel-base superalloys and steels
Process irregularities in remelting furnace operation have an impact on the ingot solidification structure which depends on the local thermal conditions and the alloy concerned. In this work, a laboratory investigation into the structures resulting from interruptions in solid growth is presented in …
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Fatigue life prediction on nickel base superalloys
… model has been developed to predict fatigue life based upon geometrical information from the initiating pores. A Paris law approach is used in conjunction with long crack propagation data. The model shows a good fit with experimental data and further improvements have been recommended in order to …
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Thermal-mechanical fatigue behavior of nickel-base superalloys
Thesis (Sc. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1986.
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Stability of nickel-base superalloys for turbine disc applications
… temperatures beyond the capabilities of current nickel-base superalloys. As a result, new alloy compositions for turbine disc applications are being developed. Optimising these alloy compositions requires balancing directly competing requirements. Increased Cr contents are needed to provide …
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Computer simulation of carburization corrosion of nickel-base superalloys
… used to simulate the corrosion behavior of Ni-based superalloys in carburizing atmospheres. The model is based on Crank-Nicholson finite difference solution of the diffusion equation. The code also includes the ternary cross diffusion effect due to substitutional alloying elements that are …
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Investigation of lattice mismatch in rhenium containing nickel-base superalloys
In this study, three techniques for measuring gamma/gamma prime lattice mismatch were examined on two alloys, each of which had two different ageing heat treatments, i.e. standard age and overaged. Each alloy contained a different Re content so that the effect of this element on lattice mismatch …
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Effect of oxygen on creep crack growth in nickel-base superalloys
Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1983.
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Development of Low-Cost Polycrystalline Nickel-Base Superalloys for Gas Turbine Applications
Polycrystalline nickel-base superalloys have found extensive application throughout the aerospace, petrochemical and power generation sectors, due to their exceptional balance of high temperature mechanical properties, thermal stability and oxidation resistance. Extensive alloy development has …
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Predicting microstructural heterogeneities in the laser powder bed fusion of γ′ strengthened nickel-base superalloys
… the laser powder bed fusion (LPBF) of CM247LC, a nickel-base superalloy with high γ′ content and hence, highly prone to weld-cracking. Multiple cracking mechanisms have been identified as active in the LPBF of various precipitation-strengthened superalloys. However, there is no precise …
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Pre-diffusion to improve the thermal fatigue strength of overlay coatings on nickel-base superalloys
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1989.
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Dynamic Compaction of Rapidly Solidified Nickel-Base Superalloys (Rapid Solidification, Powder Metallurgy, Hot Isostatic Pressing, Consolidation, Precipitation)
Rapid solidification of an experimental nickel-base superalloy was achieved using centrifugal atomization, chill-block melt-spinning and laser surface melting. Transmission electron microscopy was utilized to characterize the various microstructures obtained in terms of growth morphology, …
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Hot forging of the nickel-base superalloy ATI 718Plus
Nickel-base superalloys are widely applied in the hot section of aero engines due to their high temperature capabilities and excellent mechanical properties. For turbine discs, polycrystalline nickel-base superalloys are used where they experience temperatures up to 700ºC and stresses as high as …
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A microstructure based fatigue life prediction framework and its validation
… length, and grain boundary character. In nickel-base superalloys, fatigue cracks tend to initiate near twin boundaries. The factors causing fatigue crack initiation depend on the material’s microstructure, the variability of which results in the scatter observed in the fatigue life. In …
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Non-destructive Electrical Characterization of Controlled Waspaloy Microstructures
… evolution in this alloy via electrically-based ac/dc non-destructive techniques. Correlations were developed between electrical measurements and alternate characterization techniques such as Ultra Small Angle X-ray Scattering (USAXS), Scanning Electron Microscopy (SEM) and X-ray …
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Hydrogen embrittlement testing of alloy 718 for oil and gas applications
Hydrogen embrittlement of Ni-base corrosion resistant alloys (CRAs) can occur in deep sea oil wells when components are exposed to hydrogen while under stress. The effects of microstructure on hydrogen embrittlement of precipitation hardened Ni-base CRAs, such as alloy 718, are not fully …
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Understanding forgeability in highly reinforced cast-and-wrought superalloys
… forging of highly γ′-reinforced cast-and-wrought nickel-based superalloys. The theory postulates that surface cracking is controlled by the dissolution of the secondary γ′ phase and its subsequent reprecipitation as very fine precipitates upon cooling. The commercial alloy Udimet 720 is used as a …