Effects of unimodal secondary γ′ size and grain orientation on fatigue crack initiation and early crack propagation at room temperature have been investigated in RR1000 alloy. Fatigue tests show cracks mainly initiated at slip bands and/or pores followed by crystallographic facet formation while more diffuse strain localisation is observed around the pores by SEM-DIC analysis. Fatigue lifetime is linked to the number of crack initiations and consequent crack coalescence, which accelerates crack propagation. Slip trace analysis with EBSD mapping shows cracks are likely to propagate along the primary active slip system with a relatively high Schmid Factor. In the tests conducted here, the stochasticity of crack initiation events has more control on the overall lifetime than variations in secondary γ′ size.
ReedRC.Superalloys: fundamentals and applications. Cambridge: Cambridge University Press; 2006.
2.
GuedouJYLautridouJCHonnoratY.N18, powder metallurgy superalloy for disks: development and applications. J Mater Eng Perform. 1993; 2(4):551–556. DOI:10.1007/BF02661740
3.
AntolovichSD.Microstructural aspects of fatigue in Ni-base superalloys. Philos Trans R Soc A Math Phys Eng Sci. 2015; 373:1–36. DOI:10.1098/rsta.2014.0128
4.
JiangRKarpasitisNGaoNEffects of microstructures on fatigue crack initiation and short crack propagation at room temperature in an advanced disc superalloy. Mater Sci Eng A. 2015; 641:148–159. DOI:10.1016/j.msea.2015.05.065
5.
JiangRSongYDReedPA.Fatigue crack growth mechanisms in powder metallurgy Ni-based superalloys—a review. Int J Fatigue. 2020; 141:105887. DOI:10.1016/j.ijfatigue.2020.105887
6.
ReedPAS.Fatigue crack growth mechanisms in superalloys: overview. Mater Sci Technol. 2009; 25(2):258–270. DOI:10.1179/174328408X361463
7.
LiHYSunJFHardyMCEffects of microstructure on high temperature dwell fatigue crack growth in a coarse grain PM nickel based superalloy. Acta Mater. 2015; 90:355–369. DOI:10.1016/j.actamat.2015.02.023
8.
GaydaJGabbTPKantzosPT.The effect of dual microstructure heat treatment on an advanced nickel-base disk alloy. Superalloys. 2004; 2004:323–329. DOI:10.7449/2004/Superalloys_2004_323_329
9.
GabbTPKantzosPTTelesmanJFatigue resistance of the grain size transition zone in a dual microstructure superalloy disk. Int J Fatigue. 2011; 33(3):414–426. DOI:10.1016/j.ijfatigue.2010.09.022
10.
SarmaVSSundararamanMPadmanabhanKA.Effect of γ′ size on room temperature low cycle fatigue behaviour of a nickel base superalloy. Mater Sci Technol. 1998; 14(7):669–675. DOI:10.1179/mst.1998.14.7.669
11.
TelesmanJGabbTCargAEffect of microstructure on time dependent fatigue crack growth behavior In a P/M turbine disk alloy. Superalloys. 2008; 2008:807–816. DOI:10.7449/2008/Superalloys_2008_807_816
12.
KnowlesDMHuntDW.The influence of microstructure and environment on the crack growth behavior of powder metallurgy nickel superalloy RR1000. Metall Mater Trans A Phys Metall Mater Sci. 2002; 33(10):3165–3172. DOI:10.1007/s11661-002-0302-3
13.
StoltzREPineauAG.Dislocation-precipitate interaction and cyclic stress-strain behavior of a γ′ strengthened superalloy. Mater Sci Eng. 1978; 34(3):275–284.
14.
LerchBAJayaramanNAntolovichSD.A study of fatigue damage mechanisms in Waspaloy from 25 to 800°C. Mater Sci Eng. 1984; 66(2):151–166.
15.
PangHTReedPAS.Fatigue crack initiation and short crack growth in nickel-base turbine disc alloys – the effects of microstructure and operating parameters. Int J Fatigue. 2003; 25(9–11):1089–1099. DOI:10.1016/S0142-1123(03)00146-4
16.
LairdCFinneyJMKuhlmann-WilsdorfD.Dislocation behavior in fatigue VI: variation in the localization of strain in persistent slip bands. Mater Sci Eng. 1981; 50(1):127–136. DOI:10.1016/0025-5416(81)90093-8
17.
HealyJCGrabowskiLBeeversCJ.Short fatigue crack growth in a nickel base superalloy at room and elevated temperature. Int J Fatigue. 1991; 2:1183–1196.
18.
GotoMKnowlesDM.Initiation and propagation behaviour of microcracks in Ni-base superalloy Udimet 720 LI. Eng Fract Mech. 1998; 60(1):1–18. DOI:10.1016/S0013-7944(98)00003-4
19.
MiaoJPollockTMWayne JonesJ.Microstructural extremes and the transition from fatigue crack initiation to small crack growth in a polycrystalline nickel-base superalloy. Acta Mater. 2012; 60(6–7):2840–2854. DOI:10.1016/j.actamat.2012.01.049
20.
JiangRPierronFOctavianiSCharacterisation of strain localisation processes during fatigue crack initiation and early crack propagation by SEM-DIC in an advanced disc alloy. Mater Sci Eng A. 2017; 699:128–144. DOI:10.1016/j.msea.2017.05.091
21.
PangHTReedPAS.Effects of microstructure on room temperature fatigue crack initiation and short crack propagation in Udimet 720Li Ni-base superalloy. Int J Fatigue. 2008; 30(10–11):2009–2020. DOI:10.1016/j.ijfatigue.2008.01.001
22.
BlankenshipCPJr, HornbogenEStarkeEAJr. Predicting slip behavior in alloys containing shearable and strong particles. Mater Sci Eng A. 1993; 169(1–2):33–41.
23.
LawlessBAntolovichSDBathiasCThe effect of microstructure on the fatigue crack propagation and overload behavior of Waspaloy at room temperature. In: WellsJMLandesJD, editors. Fracture, interaction of microstructure, mechanisms, mechanics. Warrendale (PA): TMSAIME; 1985. p. 285–301.
24.
bin MaWquan LiuGfu HuBEffect of Hf on carbides of FGH4096 superalloy produced by hot isostatic pressing. Mater Sci Eng A. 2013; 587:313–319. DOI:10.1016/j.msea.2013.05.015
25.
HouJDongJXYaoZHPPB affect zone, grain boundary and phase boundary on crack propagation path for a P/M superalloy FGH4096. Mater Sci Eng A. 2018; 724:17–28. DOI:10.1016/j.msea.2018.03.066
26.
KimDJiangREvangelouAEffects of γ′ size and carbide distribution on fatigue crack growth mechanisms at 650°C in an advanced Ni-based superalloy. Int J Fatigue. 2021; 145. DOI:10.1016/j.ijfatigue.2020.106086
27.
ScottPMThorpeTW.A critical review of crack tip stress intensity factors for semi elliptical cracks. Fatigue Eng Marter Strukt. 1981; 4(4):291–309.
28.
AbuzaidWZSangidMDCarrollJDSlip transfer and plastic strain accumulation across grain boundaries in Hastelloy X. J Mech Phys Solids. 2012; 60(6):1201–1220. DOI:10.1016/j.jmps.2012.02.001
29.
VillechaisePSabatierLGirardJC.On slip band features and crack initiation in fatigued 316L austenitic stainless steel: part 1: analysis by electron back-scattered diffraction and atomic force microscopy. Mater Sci Eng A. 2002; 323(1–2):377–385. DOI:10.1016/S0921-5093(01)01381-8
30.
HarteAAtkinsonMSmithAThe effect of solid solution and gamma prime on the deformation modes in Ni-based superalloys. Acta Mater. 2020; 194:257–275. DOI:10.1016/j.actamat.2020.04.004
31.
SureshS.Fatigue of materials. 2nd ed.Cambridge: Cambridge University Press; 1998.
32.
GaoYStölkenJSKumarMHigh-cycle fatigue of nickel-base superalloy René 104 (ME3): interaction of microstructurally small cracks with grain boundaries of known character. Acta Mater. 2007; 55(9):3155–3167. DOI:10.1016/j.actamat.2007.01.033
33.
MiaoJPollockTMWayne JonesJ.Crystallographic fatigue crack initiation in nickel-based superalloy René 88DT at elevated temperature. Acta Mater. 2009; 57(20):5964–5974. DOI:10.1016/j.actamat.2009.08.022
34.
StephensRRGrabowskiLHoeppnerDW.The effect of temperature on the behaviour of short fatigue cracks in Waspaloy using an in situ SEM fatigue apparatus. Int J Fatigue. 1993; 15(4):273–282. DOI:10.1016/0142-1123(93)90376-2
