In ultra-supercritical power plants, Ni-base alloys are candidate materials for long-term, high-temperature applications, operating at temperatures and pressures as high as 750°C and 35 MPa. Alloy IN740 and its modification, alloy IN740H, are considered for such applications. Their microstructural evolution, at 750°C for times ranging between 3000 and 5000 hours, has been investigated by means of scanning electron microscopy, electron back-scattered diffraction, energy dispersive X-ray analysis and phase quantification. All phases were identified and quantified allowing comparison between the two microstructures, their evolution and stability. Particular attention was paid to γ′, η and G phases. The results are used within a broader investigation aimed at improving and further developing a predictive creep model based on continuous damage mechanics.
ViswanathanR. and BakkerW.: ‘Materials for ultrasupercritical coal power plants-boiler materials’, Part 1. J. Mater. Eng. Perform., 2001, 10, 81–95. doi: 10.1361/105994901770345394
2.
GibbonsT. B.: ‘Superalloys in modern power generation applications’, Mater. Sci. Technol., 2009, 25, 129–135. doi: 10.1179/174328408X355433
3.
SharmaA., BuhreB. J. J. P., RichardsonS., SperoC. and WallT.: ‘Fired Supercritical Boilers Operational Issues and Coal Quality Impacts’, Technical Note 20. CCSD (Cooperative Research Centre for Coal in Sustainable Development) Report, 2002.
4.
ViswanathanR., HenryJ. F., TanzosJ., StankoG., ShingledeckerJ., VitalisB. and PurgertR.: ‘U.S. Program on materials technology for ultra-supercritical coal power plants’, J. Mater. Eng. Perform., 2005, 14, 281–292. doi: 10.1361/10599490524039
5.
ReedR. C.: ‘The superalloy fundamentals and applications’, 2006, Cambridge, Cambridge University Press.
6.
ShingledeckerJ. P., SwindemanR. W., WuQ. and VasudevanV. K.: ‘Creep strength of high temperature alloys for ultra-supercritical steam boilers’, 4th EPRI Conference on Advances in Materials Technology for Fossil Power Plants, 2007.
7.
DonachieM. J. and DonachieS. J.: ‘Superalloys a technical guide’, 2002, Materials Park, OH, ASM International.
8.
EvansN. D., MaziaszP. J., SwindemanR. W. and SmithG. D.: ‘Microstructure and phase stability in INCONEL alloy 740 during creep’, Scr. Mater., 2004, 51, 503–507. doi: 10.1016/j.scriptamat.2004.05.047
9.
ShingledeckerJ. P., EvansN. D. and PharrG. M.: ‘Influences of composition and grain size on creep-rupture behaviour of Inconel alloy 740’, Mater. Sci. Eng., A, 2013, 578, 277–286. doi: 10.1016/j.msea.2013.04.087
10.
ZhaoS., XieX., SmithD. G. and PatelS. J.: ‘Research and improvement on structure stability and corrosion resistance of nickel-base superalloy INCONEL alloy 740’, Mater. Des., 2006, 27, 1120–1127. doi: 10.1016/j.matdes.2005.03.015
11.
CowenC. J., DanielsonP. E. and JablonskiP. D.: ‘The microstructural evolution of Inconel alloy 740 during solution treatment, aging, and Exposure at 760°C’, J. Mater. Eng. Perform., 2011, 20, 1078–1083. doi: 10.1007/s11665-010-9731-0
12.
OhJ.-H., ChoiI-.C., KimY.-J., YooB.-G. and JangJ.-I.: ‘Variations in overall- and phase-hardness of a new Ni-based superalloy during isothermal ageing’, Mater. Sci. Eng., A, 2011, 528, 6121–6127. doi: 10.1016/j.msea.2011.03.115
13.
PatelS. J., deBarbadilloJ. J., BakerB. A. and GollihueR. D.: ‘Nickel base superalloys for next generation coal fired AUSC power plants’, Procedia Eng., 2013, 55, 246–252. doi: 10.1016/j.proeng.2013.03.250
14.
YanC., ZhengdongL., GodfreyA., WeiL. and YuqingW.: ‘Microstructure evolution and mechanical properties of Inconel 740H during aging at 750°C’, Mater. Sci. Eng., A, 2014, 589, 153–164. doi: 10.1016/j.msea.2013.09.076
15.
WangJ., DonhJ., ZhangM. and XieX.: ‘Hot working characteristics of nickel-base superalloy 740H during compression’, Mater. Sci. Eng., A, 2013, 566, 61–70. doi: 10.1016/j.msea.2012.12.077
16.
FaulknerR. G., VujicS., Di MartinoF. and HoggS. C.: ‘Modelling of creep and fracture properties of nickel based alloys 740 and 740H’, submitted for publication.
17.
YinY. F. and FaulknerR. G.: ‘Continuum damage mechanics modelling based on simulation of microstructural evolution kinetics’, Mater. Sci. Technol., 2006, 22, (8), 929–936. doi: 10.1179/174328406X102426
18.
DysonB.: ‘Use of CDM in marerials modelling and component creep life prediction’, J. Pressure Vessel Technol., 2000, 122, 281–296. doi: 10.1115/1.556185
19.
Di MartinoS. F., FaulknerR. G. and HoggS. C.: ‘Characterisation of microstructure and creep predictions of alloy IN740 for ultrasupercritical power plants’, Mater. Sci. Technol., 2014, 31, (1), 48–58. doi: 10.1179/1743284714Y.0000000567
