Design of Inconel 706 for Improved Creep Crack Growth Resistance

Rösler, Joachim; Müller, Sebastian; Genovese, D. Del; Götting, M.

doi:10.7449/2001/superalloys_2001_523_534

Cited by 12 publications

(6 citation statements)

References 1 publication

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“…The possible role of crack tip stress relaxation in hold time crack growth behavior has been postulated by others (5,6,8). The most convincing work was by done by Molins et.al.…”

Section: Effect Of Cooling On Tdcgmentioning

confidence: 86%

Microstructural Variables Controlling Time-Dependent Crack Growth in a P/M Superalloy

Telesman¹,

Kantzos²,

Gayda³

et al. 2004

Superalloys 2004 (Tenth International Symposium)

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A study was performed to determine the variables which influence hold time crack growth resistance of Alloy 10, a new powder metallurgy (P/M) superalloy. In a well controlled study, both the effect of compositional changes and variation in heat treatments were investigated. The results indicate that significant changes in the alloy's niobium, tantalum and cobalt content did not have an appreciable effect on hold time crack growth resistance. In contrast to the composition study, the heat treatments evaluated produced up to an order of magnitude changes in the crack growth resistance. Quantitative image analysis was performed to analyze the microstructural features produced by each heat treatment. It was found that the cooling precipitate size distribution is closely related to the measured hold time crack growth behavior. The larger the mean size of the cooling precipitates, the better is the resistance to hold time crack growth. It is proposed that the size and distribution of the precipitates might play an important role in determining the extent of crack tip relaxation which occurs through creep-type processes. The differences in the stress relaxation rate influence the crack driving forces and thus crack growth resistance.

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“…The possible role of crack tip stress relaxation in hold time crack growth behavior has been postulated by others (5,6,8). The most convincing work was by done by Molins et.al.…”

Section: Effect Of Cooling On Tdcgmentioning

confidence: 86%

Microstructural Variables Controlling Time-Dependent Crack Growth in a P/M Superalloy

Telesman¹,

Kantzos²,

Gayda³

et al. 2004

Superalloys 2004 (Tenth International Symposium)

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“…Heat treatment ªBº avoids this problem as cooling is stopped at a temperature were c¢/cº precipitation is still sluggish, whereas g-phase formation occurs rapidly due to its relatively high solvus temperature. [48,35,36,39] The benefit with respect to the creep crack growth resistance is impressive, as illustrated in Figure 12. It is noteworthy in the above context that grain boundary decoration also occurs in case of Waspaloy (namely by the c¢-phase and carbides) and Inconel 617 (namely by carbides).…”

Section: Reviewsmentioning

confidence: 78%

“…Intergranular g-precipitation is less pronounced in case of heat treatment ªBstº since c¢/cº-precipitation starts already upon cooling from 980 C at the cooling rates selected here. [35,36] Isolated M(C,N)-carbonitrides of the type Ti(C,N) and (Nb,Ti)C are also observed.…”

Section: Reviewsmentioning

confidence: 88%

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Wrought Ni‐Base Superalloys for Steam Turbine Applications beyond 700 °C

Rösler¹,

Götting

Genovese

et al. 2003

Adv Eng Mater

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The development of a new steam turbine generation for use in advanced coal fired power plants with prospective operating temperatures beyond 700 °C and a projected thermodynamic efficiency of about 55 % requires, amongst other innovations, the partial substitution of ferritic steels by wrought Ni‐base superalloys. Although Ni‐base alloys are already widely used in the aerospace industry, they are faced with demands regarding component size and operation temperature, which by far exceed current aero‐engine requirements. In this article, the potential of selected alloys for 700 °C steam turbine applications is discussed with respect to their manufacturability and mechanical performance. Hereby, the focus is on the steam turbine rotor, which probably is the most critical component. It is concluded that material solutions are available for operation conditions around 600 °C but not for temperatures of 700 °C and above. Based on these results, alloy development strategies are suggested in order to close this gap and two new alloys, DT 706 and DT 750, are introduced.

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“…However, the technical and economic feasibility of this development concept fundamentally relies on the application of nickel-based alloys to enable the high (700-720 • C) steam temperatures. The commercial alloy Inconel 706 was a candidate, but was found to be unstable for application at these high temperatures [1]. The experimental polycrystalline Ni-Fe-based superalloy DT706 used in the present study is derived from the commercial Inconel 706 alloy and was developed for disk application in steam turbines for use at temperatures above 700 • C. The development of DT 706 alloy was aimed at improving the microstructural stability of Inconel 706, while preserving its excellent manufacturability and good mechanical properties.…”

Section: Introductionmentioning

confidence: 99%

Microstructural characterisation of a Ni–Fe-based superalloy byin situsmall-angle neutron scattering measurements

Mukherji

Genovese

Strunz

et al. 2008

J. Phys.: Condens. Matter

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The microstructural evolution at high temperatures was studied in an experimental Ni–Fe-based superalloy DT706 by in situ small-angle neutron scattering (SANS). Modifying the alloy heat treatment to improve the microstructural stability and mechanical properties in Inconel 706 type superalloys has been a significant research goal for many years. The earlier studies of phase transformation relied mostly on optical and electron microscopy investigations of samples that were cooled down to room temperature after the high-temperature exposure. However, the kinetics of γ′ and γ′′ precipitation is very fast and new precipitation does occur during the cooling phase. So it is unlikely that the high-temperature microstructure is retained at room temperature. In this presentation, we followed the phase transformation in DT706 alloy by studying the microstructural changes occurring at elevated temperatures. The results of in situ SANS measurements are presented. Microstructure examination on differently heat-treated samples by electron microscopy gives complementary information on the phase transformation sequences. The formation and evolution of precipitates are strongly influenced by the cooling rate from the solution to the η stabilization temperature. The microstructure of DT706 alloy can be tuned using the in situ SANS results.

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Design of Inconel 706 for Improved Creep Crack Growth Resistance

Cited by 12 publications

References 1 publication

Microstructural Variables Controlling Time-Dependent Crack Growth in a P/M Superalloy

Microstructural Variables Controlling Time-Dependent Crack Growth in a P/M Superalloy

Wrought Ni‐Base Superalloys for Steam Turbine Applications beyond 700 °C

Microstructural characterisation of a Ni–Fe-based superalloy byin situsmall-angle neutron scattering measurements

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