In the present paper, to investigate the effect of vacancy diffusion and concentration on creep crack initiation and growth process for weldments, the numerical analyses of diffusion and concentration of vacancy around a notch tip of C(T) specimen in the heat affected zone (HAZ) were conducted based on the proposed 𝛼 multiplication and FEM-FDM methods. As an analytical result, the vacancy diffusion and concentration behavior around a notch tip of C(T) specimen in the heat affected zone for P92 steel was found to be dominated by the distribution of multi-axiality of the stress caused by inhomogeneous property of regions of fine and coarse grains in HAZ. It is also found to be closely related to the creep damage formation and the initial direction of creep crack growth.
MasuyamaF., Creep degradation in welds of Mod.9Cr-1Mo steel, International Journal of Pressure Vessels and Piping83 (2006), 819–825.
2.
FalatL.VyrostkovaA.HomolovaV. and SvobodaM., Creep deformation and failure of E911 E911 and P92 P92 similar weld-joints, Engineering Failure Analysis16 (2009), 2114–2120.
3.
TabuchiM.HongoH.LiY.WatanabeT. and TakahashiY., Evaluation of microstructures and creep damages in the HAZ of P91 steel weldment, Transactions of the ASME Journal of Pressure Vessel Technology131 (2009), 021406.
4.
ZhaoL.JingH.XuL.HanY. and XiuJ., Experimental study on creep damage evolution process of type IV cracking in 9Cr-0.5Mo-1.8W-VNb steel welded joint, Engineering Failure Analysis19 (2012), 22–31.
5.
YamadaS.YaguchiM. and OgataT., Microstructural change of a 9Cr steel longitudinal welded tube under internal pressure creep loading, Materials Science and Engineering A560 (2013), 450–457.
6.
LiY.HongoH.TabuchiM.TakahashiY. and MonmaY., Evaluation of creep damage in heat affected zone of thick welded joint for Mod.9Cr-1Mo steel, International Journal of Pressure Vessels and Piping86(9) (2009), 585–592.
7.
YaguchiM.OgataT. and SakaiT., Creep strength of high chromium steels welded parts under multiaxial stress conditions, International Journal of Pressure Vessels and Piping87(6) (2010), 357–364.
8.
Yokobori JrA.T.SugiuraR.TabuchiM.YatomiM.KobayashiK. and NikbinK., Definition and estimation method of incubation time of creep crack growth for high Cr steels and their weldments (creep crack initiation), Strength Fracture and Complexity7(3) (2011), 315–320.
9.
YokoboriT. and IchikawaM., A kinetic theory of fatigue crack growth growth based on vacancy condensation mechanism, Rep Res Inst Strength and Fracture Tohoku Univ6 (1970), 75–86.
10.
LeeuwenH.P., The kinetics of hydrogen embrittlement: A quantitative diffusion model, Eng. Fract. Mech.6 (1974), 141–161.
11.
Yokobori JrA.T.NemotoT.SatohK. and YamadaT., Numerical analysis on hydrogen diffusion and concentration in solid with emission around the crack tip, Eng. Fract. Mech.55(1) (1996), 47–60.
12.
Yokobori JrA.T.OhmiT.MurakawaT.NemotoT.UesugiT. and SugiuraR., The application of the analysis of potential driven particle diffusion to the strength of materials, Strength, Fracture Complexity7(2) (2011), 215–233.
13.
Yokobori JrA.T.UesugiT.SendohM. and ShibataM., The effect of stress wave form on corrosion fatigue crack growth rate on the basis of hydrogen diffusion theory, Strength, Fracture Complexity1(4) (2003), 187–204.
14.
OhmiT.Yokobori JrA.T. and TakeiK., Flow controllability of hydrogen diffusion driven by local stress field for steel under cyclic loading condition, Defect and Diffusion Forum626 (2012), 326–328.
15.
Yokobori JrA.T.AbeK.TsukidateH.OhmiT.SugiuraR. and IshikawaH., Micro mechanics based on vacancy diffusion coupled with damage mechanics related to creep deformation and prediction of creep fracture life, Materials at High Temperatures28 (2011), 126–136.
16.
Yokobori, JrA.T.SugiuraR.OhmiT. and AinsworthR., A review of a time-dependent fracture life law (or Model) based on a proposed multi-scale analysis, Strength, Fracture and Complexity8 (2013/2014), 205–218.
17.
Yokobori JrA.T. and OhmiT., The significance of 𝛼 multiplication method for numerical analysis of potential induced particle diffusion, Strength, Fracture and Complexity8 (2013/2014), 117–124.
18.
SugiuraR.Yokobori JrA.T.SatoK.TabuchiM.YatomiM.KobayashiK. and NikbinK., Creep crack initiation and growth characteristics in weldment for P92 based on C*, dδ/dt and Q* parameters, Strength, Fracture and Complexity6(4) (2011), 177–189.
19.
TabuchiM.YokoboriA.T.Jr.SugiuraR.YatomiM.FujiA.KobayashiK. and YokoboriT., VAMAS TWA31 ANNUAL MEETING ’08. Document May 19th., London, UK, 2008.
20.
PatankarS. V., Numerical heat transfer and fluid flow, Taylor & Francis, 1980.
