On the mechanism of serrated grain boundary formation in Ni-based superalloys

Koul, A. K.; Gessinger, Gernot H.

doi:10.1016/0001-6160(83)90202-x

Cited by 105 publications

(62 citation statements)

References 7 publications

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“…It was hoped that the fine gamma prime particle distribution resulting from the rapid quench from above γ' solvus would enable strength-dependent properties required in the bore. 9,10 The time-dependent properties required of the disk rim would be enabled by a coarse grain microstructure with serrated grain boundary morphology. 11,12 Attempts were made to address notch sensitivity in the blade attachment slot by subjecting all materials to a stabilization heat treatment at 871°C for 4 hrs.…”

Section: Introductionmentioning

confidence: 99%

P/M Alloy 10: A 700�C Capable Nickel-Based Superalloy for Turbine Disk Applications

Rice¹,

Kantzos²,

Hann³

et al. 2008

Superalloys 2008 (Eleventh International Symposium)

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The Versatile Affordable Advanced Turbine Engine (VAATE) program has been supporting the development of Alloy 10, a gasatomized powder metal (PM) superalloy. Funding for the program was provided by U.S. Air Force Research Laboratory (AFRL).Honeywell International, Rolls Royce -Allison Advanced Development Company (AADC), and Williams International have been jointly developing Alloy 10 for small and large gas turbine engine applications. Alloy 10 is a demonstrated industry leader in high temperature creep resistance, and has been produced using production-scale equipment for high pressure turbine disk applications. To address cost issues, the VAATE Alloy 10 project evaluated the relative differences between material densified by hot isostatic pressing (as-HIP) and material produced by extrusion followed by isothermal forging. The program was completed as a series of four tasks: (i) chemistry optimization, (ii) as-HIP compaction, (iii) HIP compaction plus isothermal forging for small engine applications, and (iv) extrusion plus isothermal forging for large engine applications. This report provides the status of the program, microstructures typical of the various Alloy 10 product forms, and a summary of initial mechanical properties data.

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Section: Introductionmentioning

confidence: 99%

P/M Alloy 10: A 700�C Capable Nickel-Based Superalloy for Turbine Disk Applications

Rice¹,

Kantzos²,

Hann³

et al. 2008

Superalloys 2008 (Eleventh International Symposium)

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“…Grain boundary serrations have been studied not only in nickel base superalloys but also in steels and cobalt base alloys (2,3,4). Several investigations were performed to improve, through this particular grain boundary geometry, the crack propagation resistance of disc alloys, especially in INC0718 alloy (5).…”

Section: Introductionmentioning

confidence: 99%

“…The models to date are qualitative and discribe the phenomena by an interaction between the grain boundary and precipitates, in order to explain the modification in the grain-boundary geometry (3). The precipitates that are responsible for the serrations include the y ' phase in nickel base superalloys or M23C6 type carbides in austenitic stainless steels (6).…”

Section: Introductionmentioning

confidence: 99%

Formation of Serrated Grain Boundaries and Their Effect on the Mechanical Properties in a P/M Nickel Base Superalloy

Danflou¹,

Marty²,

Walder³

1992

Superalloys 1992 (Seventh International Symposium)

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To improve the crack propagation resistance of disk alloys, a study of the influence of the different heat treament parameters, which control the grain boundary geometry, was performed on Astroloy fabricated by a powder metallurgy process. Grain boundary serrations, associated with the precipitation of adjacent coarse y ' precipitates, were obtained by heat treating above the solvus for the alloy followed by slow cooling. The size of these coarse y ' precipitates can be controlled by the heat treatment parameters which include: homogenizing temperature, cooling rate and cooling range.The presence of grain boundary precipitates creates serrations by discontinuous precipitation of the y ' phase in the grain boundary region. The precipitates responsible for serrations were uniformly distributed on both sides of the boundaries. The amplitude of the serrations increase with the misorientation between grains. Tensile tests at 750°C showed no real difference between the microstructures, with and without serrations; however the creep fatigue crack growth rate in the alloy with serrated boundaries was found to be significantly slower than that observed in the unserrated material.

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“…Larson [26] suggested that the serrated grain boundary formation is associated with the heterogeneous nucleation of γ' at the grain boundaries, and the migration of grain boundary sections between the primary γ' particles. Koul [27] proposed that the net strain energy difference between the matrix side and the boundary side of the particle matrix interface provided a driving force for the movement of primary γ' particles in the direction of the boundary. On the other hand, Yoo [24] suggested that the serrated grain boundary formation is related with asymmetric growth of precipitates.…”

Section: ) Effect Of Serrated Grain Boundarymentioning

confidence: 99%

Effects of Grain Boundary Morphologies on Stress Corrosion Cracking of Alloy 600

Kim

Choi

Kim

et al. 2017

Archives of Metallurgy and Materials

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Effects of grain boundary morphologies on stress corrosion cracking (SCC) of Alloy 600 have been studied in 40% NaOH at 315°C using C-ring specimens. The configuration of the grain boundary and the intergranular carbide density were controlled by heat treatment. SCC tests were performed at +150 mV above the corrosion potential. The specimen with a serrated grain boundary showed higher SCC resistance than that with a straight grain boundary. This appears to be caused by the fact that the specimen with the serrated grain boundary has longer SCC path. SCC resistance also increased with intergranular carbide density probably due to enhanced relaxation of stress at intergranular carbide.

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On the mechanism of serrated grain boundary formation in Ni-based superalloys

Cited by 105 publications

References 7 publications

P/M Alloy 10: A 700�C Capable Nickel-Based Superalloy for Turbine Disk Applications

P/M Alloy 10: A 700�C Capable Nickel-Based Superalloy for Turbine Disk Applications

Formation of Serrated Grain Boundaries and Their Effect on the Mechanical Properties in a P/M Nickel Base Superalloy

Effects of Grain Boundary Morphologies on Stress Corrosion Cracking of Alloy 600

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