Mechanical response of HVOF-coated workpieces is important for the life assessment of coating adherence, particularly for the coated surfaces being exposed to high-temperature environments prior to mechanical tests. In the present study, fatigue tests are carried out for Ti-6Al-4V workpieces coated via HVOF spraying of AMDRY 995 (CoNiCrAlY) powders. In order to simulate the effect of high temperature on the fatigue response of coating, workpieces were heat treated at the annealing temperature of the alloy for 1 h. Surface morphology prior to and after fatigue testing is carried out using scanning electron microscopy (SEM) and optical microscopy, while energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) are carried out for metallurgical examinations. It is found that heat treatment results in early fatigue failure of the workpieces owing to thermally induced stresses developed at the coating-substrate interface. The metallurgical changes in the substrate material, and formation of brittle oxygen compounds and alumina particles left over from grit blasting at the coating-substrate material interface are responsible for the coating failure.
BrandtO. C.Mechanical properties of HVOF coatings. J. Thermal Spray Technol., 1995, 4(2), 147–152.
2.
Natali SoraI.MorF.La VecchiaG. M.ZocchiM.Structural changes in high velocity oxyfuel sprayed Cr2C2/NiCr 75/25 coatings after annealing treatments. Mater. Sci. Forum, 1998, 278-281. 520–525.
3.
De PaloS.MohantyM.Marc-CharlesH.DorfmanM.Fracture toughness of HVOF sprayed WC-Co coatings. Thermal spray: Surface engineering via applied research. In Proceedings of the 1st International Thermal Spray Conference, Montreal, Canada (Ed. BerndtC. C.), 2000, pp. 245–250.
4.
HernándezL.OliveiraF.Berr osJ. A.VillalobosC.PertuzA.Puchi CabreraE. S.Fatigue properties of a 4340 steel coated with a Colmonoy 88 deposit applied by high-velocity oxygen fuel. Surf. Coatings Technol., 2000, 133-134. 68–77.
5.
GassotH.JunqueraT.JiV.JeandinM.GuipontV.CoddetC.VerdyC.GrandsireL.Comparative study of mechanical properties and residual stress distributions of copper coatings obtained by difference thermal spray processes. Surf. Engng., 2001, 17(4), 317–322.
6.
Higuera HidalgoV.Belzunce VarelaJ.Carriles MenendezA.Poveda MartinezS.Experimental study effects of thermal spray procedure and thermal fatigue on microstructure and properties of NiCrAlMoFe coating. Surf. Engng., 2001, 17(6), 512–517.
7.
PadillaK.VelsquezA.BerraosJ. A.Puchi CabreraE. S.Fatigue behavior of a 4140 steel coated with a NiMoAl deposit applied by HVOF thermal spray. Surf. Coatings Technol., 2002, 150, 151–162.
BurkleG.BanhartF.SagelA.WankeC.CorrpnickG.FechtH. J.Determination of the mechanical properties of nanocrystalline Fe-Cr-based thermal spray coatings. Mater. Sci. Forum, 2002, 386(3), 571–576.
10.
LiH.KhorK. A.CheangP.Young's modulus and fracture toughness determination of high-velocity oxy-fuel-sprayed bioceramic coatings. Surf. Coatings Technol., 2002, 155(1), 21–32.
11.
HamataniH.IchiyamaY.KobayashiJ.Mechanical and thermal properties of HVOF sprayed Ni-based alloys with carbide. Sci. Technol. Adv. Mater., 2002, 3(4), 319–326.
12.
TotemeierT. C.WrightR. N.SwankW. D.Mechanical and physical properties of high-velocity oxy-fuel-sprayed iron aluminide coatings. Phys. Metall. Mater. Sci. Trans. Metall. Mater., 2003, 34A(10), 2223–2231.
13.
PejrydL.WigrenJ.GrevingD. J.ShadleyJ. R.RybickiE. F.Residual stresses as a factor in the selection of tungsten carbide coatings for a jet engine application. J. Thermal Spray Technol., 1995, 4, 268–274.
14.
McGrannR. T. R.GrevingD. J.ShadleyJ. R.RybickiE. F.BodgerB. E.SomervilleD. A.Effect of residual stress in HVOF tungsten carbide coatings on the fatigue life in bending of thermal spray coated aluminum. J. Thermal Spray Technol., 1998, 7(4), 546–552.
15.
IbrahimA.BerndtC. C.The effect of HFPD thermally sprayed WC-Co coatings on the fatigue behavior and deformation of Al 2024-T4. In Proceedings of the International thermal spray conference, Montreal, Canada, 2000, pp. 1297–1301. (ASM International, Materials Park, Ohio).
16.
McGrannR. T. R.ShadleyJ. R.RybickiE. F.BodgerB. E.EmeryW. A.SomervilleD. A.GrevingD. J.Evaluation of residual stresses and fatigue life of tungsten carbide thermal spray coated aircraft landing gear materials. In Proceedings of the International thermal spray conference, Montreal, Canada, 1998, Vol. 1, pp. 557–562. (ASM International, Materials Park, Ohio).
17.
Al-FadhliH. Y.StokesJ.HashmiM. S. J.YilbasB. S.HVOF coating of welded surfaces: Fatigue and corrosion behavior of stainless steel coated with Inconel-625 alloy. Surf. Coatings Technol., 2006, 200 (16-17), 4904–4908.
18.
RinaldiC.FerravanteL.Uberti PaciF.BianchiP.Extensive characterization of dense and corrosion resistant coatings produced by improved shrouded techniques. In Proceedings of the International thermal spray conference, Montreal, Canada, 2001, pp. 1185–1193. (ASM International, Materials Park, Ohio).
19.
Al-FadhliH. Y.Performance evaluation of (HVOF) thermal spray coating using INCONEL-625 powder. MSc Thesis, Mechanical Engineering Department, King Fahd University of Petroleum and Minerals, Saudi Arabia, 2003.
20.
OhJ.KimN. J.LeeS.EuiL. W.Correlation of fatigue properties and microstructure in investment cast Ti-6Al-4V welds. Mater. Sci. Engng, 2003, A340, 232–242.
21.
WatanabeS.TajiriT.SakodaN.AmanoJ.Fatigue cracks in HVOF thermally sprayed WC-Co coatings. J. Thermal Spray Technol., 1998, 7(1), 93–96.
22.
BaeslackW. A.IIIBaeslackW. A.Evaluation of triplex post-weld heat treatments for alpha-beta titanium alloys. Welding J., 1982, 61(6), 197.
23.
EylonD.HallJ.A fatigue behavior of beta processed titanium alloys IMI 685. Metall. Trans. A, 1977, 8A(6), 981–990.
24.
Keshava MurthyK.PotluriN. B.SundaresanS.Fusion zone microstructure and fatigue crack growth behaviour in Ti-6Al-4V alloy weldments. Mater. Sci. Technol., 1997, 13(6), 503.
