Julio Cesar Costa Leite. Notch sensitivity in environmentally assisted cracking (EAC): methodologies and specimens analyses. Dissertação de Mestrado

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1 Julio Cesar Costa Leite Notch sensitivity in environmentally assisted cracking (EAC): methodologies and specimens analyses Dissertação de Mestrado Thesis presented to the Programa de Pós-graduação em Engenharia Mecânica of the Departamento de Engenharia Mecânica do Centro Técnico Científico da PUC-Rio, as partial fulfillment of the requirements for the degree of Mestre. Advisor: Prof. Jaime Tupiassú Pinho de Castro Rio de Janeiro March 20, 2014

2 Julio Cesar Costa Leite Notch sensitivity in environmentally assisted cracking (EAC): methodologies and specimens analyses Thesis presented to the Programa de Pós-graduação em Engenharia Mecânica of the Departamento de Engenharia Mecânica do Centro Técnico Científico da PUC-Rio, as partial fulfillment of the requirements for the degree of Mestre. Approved by the following commission: Prof. Jaime Tupiassú Pinho de Castro Advisor Departamento de Engenharia Mecânica PUC-Rio Prof. Marco Antônio Meggiolaro Departamento de Engenharia Mecânica PUC-Rio Prof. Arthur Martins Barbosa Braga Departamento de Engenharia Mecânica PUC-Rio Prof. Antônio Carlos de Oliveira Miranda Departamento de Engenharia Civil UNB-DF Prof. José Eugênio Leal Coordinator of the Centro Técnico Científico PUC-Rio Rio de Janeiro March 20, 2014

3 All rights reserved. It is forbidden partial or complete reproduction without previous authorization of the university, the author and the advisor. Julio Cesar Costa Leite Graduated in Telecommunications Engineering from Universidade Federal Fluminense (Niterói, Brazil) in 2005 and post-graduated in Petroleum Engineering from Universidade Federal da Bahia (Salvador, Brazil) in Currently works as a petroleum engineer in the well completions service unit of Petrobras. Bibliographic Data Leite, Julio Cesar Costa Notch sensitivity in environmentally assisted cracking (EAC): methodologies and specimens analyses / Julio Cesar Costa Leite; advisor: Jaime Tupiassú Pinho de Castro f. : il. (color.) ; 30 cm Dissertação(mestrado) Pontifícia Universidade Católica do Rio de Janeiro, Departamento de Engenharia Mecânica, Inclui bibliografia 1. Engenharia Mecânica Teses. 2. Trincas curtas. 3. Trincas não propagantes. 4. Efeitos de meio-ambiente. 5. Sensibilidade ao entalhe. I. Castro, Jaime Tupiassú Pinho de. II. Pontifícia Universidade Católica do Rio de Janeiro. Departamento de Engenharia Mecânica. III. Título. CDD: 621

4 To my parents, for my character-building.

5 Acknowledgments The author is very grateful to PETROBRAS S.A. for the investments in his academic education and to Dr. Jaime Tupiassú Pinho de Castro for his dedication and continued support.

6 Abstract Leite, Julio Cesar Costa; Castro, Jaime Tupiassú Pinho de. Notch sensitivity in environmentally assisted cracking (EAC): methodologies and specimens analyses. Rio de Janeiro, p. MSc Dissertation Departamento de Engenharia Mecânica, Pontifícia Universidade Católica do Rio de Janeiro. Semi-empirical notch sensitivity factors q have been used for a long time to quantify notch effects in fatigue design. This old concept has been recently modeled using sound mechanical principles to properly quantify the influence of the stress gradient around the notch tip on the fatigue behavior of mechanically short cracks. This model predictions have been validated by proper tests, and based on this experimental evidence a criterion to accept tolerable short cracks has been proposed. In this work the mechanical principles that support this criterion are extended, in an unprecedented way, to account for notch effects in environmentally assisted cracking problems using two methodologies to calculate q values from the basic EAC materials strength, its EAC resistance to crack initiation and its EAC crack propagation threshold, considering all the characteristics of the notch geometry and of the loading applied on four common specimens on the standards. Keywords sensitivity. Short cracks; Non-propagating cracks; Environmental effects; Notch

7 Resumo Leite, Julio Cesar Costa; Castro, Jaime Tupiassú Pinho de. Sensibilidade ao entalhe em corrosão assistida pelo ambiente: metodologias e análise de corpos de prova. Rio de Janeiro, p. Dissertação de Mestrado Departamento de Engenharia Mecânica, Pontifícia Universidade Católica do Rio de Janeiro. O fator semi-empírico de sensibilidade ao entalhe q vem sendo utilizado ao longo dos anos para quantificar os efeitos de entalhes em projetos de fadiga. Este conceito antigo tem sido modelado recentemente com base em princípios mecânicos sólidos para quantificar de maneira apropriada a influência do gradiente de tensão, na proximidade da raiz do entalhe, no comportamento de trincas de fadiga consideradas mecanicamente como curtas. As previsões propostas por este modelo foram validadas por testes apropriados, e baseando-se nestas evidências experimentais pode ser proposto um critério de tolerância a trincas curtas de fadiga. Neste trabalho tanto os princípios mecânicos como o critério de tolerância são estendidos, de forma inédita, para a análise de trincas curtas provenientes de ambientes corrosivos. Duas metodologias distintas para o cálculo de q são propostas utilizando a resistência à iniciação de trinca e a resistência à propagação de trinca, ambas em condições de EAC, e aplicadas em quatro corpos de prova comumente encontrados nas normas, a fim de avaliar os efeitos da geometria e das cargas aplicadas nestes espécimes. Palavras chave Trincas Curtas; Trincas não propagantes; Efeitos de Meio-Ambiente; Sensibilidade ao entalhe.

8 Contents List of Figures 10 List of Tables 17 List of Symbols 20 List of Acronyms 23 1 Introduction Problem Description Objectives 30 2 Notch Sensitivity Short cracks influence on the fatigue limit of structural components Engineering estimates for notch effects on the FCG behavior of short cracks Analysis of notch sensitivity effects in fatigue Experimental verification of the notch sensitivity predictions Notch sensitivity effects on environmentally assisted cracking 62 3 EAC Notch Sensitivity Analysis on Common Specimens Finite Element Methodology for the Stress Intensity Factor KI Mixed Methodology for the Stress Intensity Factor KI 93 4 Results Finite Elements Methodology Results Stress Concentration Factor (Kt) & Stop Crack Size (ast). 107

9 Threshold Nominal Stress on Notch Tip (SLntc), Stress Concentration Factor under EAC (KtEAC) and Notch Sensitivity under EAC (qeac) Mixed Methodolgy and Results Comparison of Methodologies Conclusions Bibliography 126

10 List of Figures Figure 1 - Pitting Corrosion on 13Cr Tubing. 27 Figure 2 - Tubing collar (Material: API P-110) cracked on service on an oil producer reservoir containing H2S. (Courtesy of PETROBRAS Research Center CENPES) 28 Figure 3 - Stress ranges σ(a) required to propagate cracks of size a under R = 0 in a HT80 steel plate with K0 = 11.2MPa m and S0=575MPa: long cracks, with a >> a0, stop when σ K0/ πa, while very short cracks, with a 0, stop when σ S0. The ETS mode l predicts that any crack should stop when σ K0/ [π(a+a0)]. 33 Figure 4 - The additional parameter γ in ΔK0(a)/ΔK0=[1 + (a0/a) γ/2 ] -1/γ may allow a better fitting of the short crack FCG thresholds measured experimentally. 36 Figure 5 - Influence of γ in the fatigue limit curves σ0(a) predicted by equation (9): the larger the γ value is, the faster σ0(a) tends to the bilinear limit defined by σ0 = K0/ (πa), the FCG threshold under pulsating loads for long cracks with size a >> a0, and to σ0 = S0, the fatigue limit under pulsating stresses for very small cracks with a << a0. 37 Figure 6 - Larger stress ranges tolerable under several R ratios in function of the edge crack size a, for W = 3.4mm, η= 1.12, K0=6MPa m, a0 = 59µm, γ = 6, and φf = Figure 7 - The ratio K1.2 = σy(x/b = 1.2, 0)/σn at the point that is just b/5 ahead the tip of any elliptical hole is almost independent of its Kt (in the LE case). 43 Figure 8 - KI 1.12 σn (πa) f1(kt, a) estimate for small cracks a b/5 that start from the tip of an Inglis hole with b = 10mm. 43

11 Figure 9 - A crack does not start at the circular hole (that tolerates cracks a < 1.5mm), while the crack that begins at the elliptical hole stops at ast 0.33mm. 45 Figure 10 - Cracks that can start from the border of a (small) Kirsch hole may propagate by fatigue and then stop if their ϕ/g < 1 (ρ 1.40 a0, κ = 1.5, and γ = 6 in this figure). 48 Figure 11 - After leaving the region affected by the Kirsch hole, the cracks SIF steadily grow as their size a increases (as usual for far field loaded cracks), thus even small stress ranges σ can propagate them by fatigue when they are sufficiently long. 49 Figure 12 - Fatigue behavior under fixed pulsating loads of short crack that depart from a larger Kirsch hole border with κ=η (πa0/ρ)=0.3 ρ 7 a0, for γ = 6: almost all cracks that start under σ do not arrest their propagation, thus this hole has q Figure 13 - SIF for cracks that depart from semi-elliptical notches with c b. 52 Figure 14 - Notch sensitivity q(1/κ) estimated for a (circular) Kirsch hole. 52 Figure 15 - Notch sensitivity q for Kirsch holes, estimated using mean ΔK0 and ΔS0 values from 450 steels and Al alloys, supposing γ=6. Note that q = 0 means that it is easier to initiate a crack from a free surface than from the border of very small holes. 55 Figure 16 - Notch sensitivity q in function of the tip radius ρ of semielliptical notches in Al alloys, estimated using a0=(1/π) ( K0/1.12SL) 2 = 264µm, SU = 225MPa, and γ= Figure 17 - Notch sensitivity q in function of the tip radii ρ of semielliptical notches predicted for steels with SU= 800MPa, SL=400MPa, K0 = 8MPa m, a0 102µm, and γ = 6. 56

12 Figure 18 - TS used to test the stop-hole size effect on their efficiency as a crack repair method, and typical results obtained with them. 58 Figure 19 - Fatigue crack re-initiation lives for the stop-hole root with radius ρ = 3.0mm, measured and predicted using the resulting semielliptical notch Kt. 60 Figure 20 - Fatigue crack re-initiation lives for the stop-hole root with radius ρ = 1.0mm, measured and predicted using the resulting semielliptical notch Kt. 60 Figure 21 - Fatigue crack re-initiation lives for the stop-hole root with radius ρ = 3.0mm, measured and predicted using the resulting semielliptical notch Kf. 61 Figure 22 - Fatigue crack re-initiation lives for the stop-hole root with radius ρ = 1.0mm, measured and predicted using the resulting semielliptical notch Kf. 62 Figure 23 - A Kitagawa-Takahashi-like diagram proposed to describe the environmentally assisted cracking behavior of short and deep flaws for structural design purposes. 65 Figure 24 - Modified Kitagawa diagram including fatigue and EAC limiting conditions for crack growth, showing the contribution of mechanical residual stresses and of equivalent chemical stresses involved in corrosion-fatigue problems. 67 Figure 25 - TS used for measuring SEAC according to ASTM E1681 standard procedures. 68 Figure 26 - TS used for measuring KIEAC according to ISO 7579 standard procedures. 69 Figure 27 - Notched TS after being tested under σmax > 2 SEAC. 70 Figure 28 - Modified C(T) sample based on ASTM E647-13e1. 71 Figure 29 - Modified M(T) sample based on ASTM E647-13e1. 72 Figure 30 - Modified SEN(B) sample based on ASTM E e2. 72

13 Figure 31 - Modified SEN(T) sample based on Rabbe et al. 73 Figure 32 - SEN(T) specimen: The threshold crack propagation KIth (green); KI considering the notch tip stress σntc =80 MPa (Blue ); KI (red) considering the nominal stress at the notch tip σn = SLntc which leads to σntc = Kt SLntc = 136.8MPa. 75 Figure 33 - Geometric parameters of modified C(T) sample and its nominal stress applied at the notch tip. 76 Figure 34 - Geometric parameters of modified M(T) sample and its nominal stress applied at the notch tip. 77 Figure 35 - Geometric parameters of modified SEN(B) sample and its nominal stress applied at the notch tip. 77 Figure 36 - Geometric parameters of modified SEN(T) sample and its nominal stress applied at the notch tip. 78 Figure 37 - Length reference, used on the proposed model, for the cracks that depart from the notch tip. 79 Figure 38 - Cartesian chart and Excell spreadsheet showing KIth(a)xa, for the Aluminum 2024 under liquid Gallium attack: SEAC=45 MPa ; KIEAC=8.5 MPa m; a0=9.05mm. 80 Figure 39 - Quebra2D: (a) Stress Analysis on a non-cracked C (T) specimen, (b) Detail of the stress distribution on the vicinity of the notch tip of a non-cracked C (T) specimen, (c) Detail of the stress distribution on a propagating crack initiated at the notch tip of C(T) specimen. 82 Figure 40 - C(T) specimen based on ASTM E647-13e1 modeled on Quebra2D with the following parameters : W=50mm, b=20mm, ρ=2mm, t=6mm, E=70 GPA, ν=0, Figure 41 - Loads and constraints applied on the specimens. C(T) and SEN(B) specimens are constrained only on y-direction. SEN(T) and M(T) specimens are constrained on x-direction and y-direction. 83

14 Figure 42 - Quebra2D mesh refinement process: (a)first mesh generated with the default numbers of nodes/edge (5); (b)the first mesh refinement, increasing the number of nodes all around the model; (c)last mesh refinement increasing the number of nodes on the notch tip; (d)notch detail showing the mesh refinement. 86 Figure 43 - Kt result for a C(T) specimen with the following parameters: W=50mm, b=20mm, ρ=2mm, t=6mm, E=70 GPA, ν=0.33: (a)stress distribution on y-direction (σy); (b)detail indicating higher stresses values and higher stress gradient around the notch tip; (c)kt obtained by the analytical value of nominal stress on y-direction (σn) and the stress at the notch tip (σntc) on y-direction obtained with Quebra2D. 86 Figure 44 - (a) Stress distribution (σy) around the notch tip on a noncracked C(T) specimen; (b)tiny crack (a=0.01mm) introduced on the notch tip to provide a start to the propagation analysis; (c)mesh created considering the induced crack (with 5 nodes); (d)stress distribution (σy) due the introduction of the tiny crack. 87 Figure 45 - Quebra2D crack s propagation input parameters: (a)crack length s increment; (b)stopping criteria for the crack s propagation; (c)technique to calculate stress intensity factors; (d)techniques to calculate the crack s propagation direction. 88 Figure 46 - KIth(a) and KI(a) on a C(T) specimen: W=50mm, b=20mm, ρ=2mm, t=6mm, E=70 GPA, ν= Figure 47 - KI(a) - KIth(a) on a C(T) specimen: W=50mm, b=20mm, ρ=2mm, t=6mm, E=70 GPA, ν= Figure 48 - Refinement of KIth(a) and KI(a) on a C(T) specimen: W=50mm, b=20mm, ρ=2mm, t=6mm, E=70 GPA, ν=0.33. This analysis provides a better result for ast. 90 Figure 49 - Refinement of KI(a) - KIth(a) on a C(T) specimen: W=50mm, b=20mm, ρ=2mm, t=6mm, E=70 GPA, ν=0.33. This analysis provides a better result for ast. 90

15 Figure 50 - C(T) Specimen W=50mm, b=20mm, ρ=2mm, t=6mm, E=70 GPa, ν=0.33: KI function (Blue) with σntc=80mpa; KI function (Red) adjusted in order to obtain SLntc. 92 Figure 51 - C(T) Specimen W=50mm, b=20mm, ρ=2mm, t=6mm, E=70GPa, ν = 0.33: KI - KIth (Blue) with σntc=80mpa; KI-KIth function (Red) adjusted in order in order to obtain SLntc. 93 Figure 52 - Stress Field based on KI, obtained by Irwin and Williams, on the vicinity of the crack tip. 94 Figure 53 - Coordinates used on the model proposed by Creager and Paris. 94 Figure 54 - Coordinates used on the standards for KI evaluation. Kt is calculated considering a = b. 96 Figure 55 - KIth(a) and KIclose(a) obtained for the C(T) specimen: W=50mm, b=20mm, ρ=2mm, t=6mm, E=70GPA, ν=0.33, σntc=80mpa. 101 Figure 56 - KIclose(a) - KIth(a) for the C(T) specimen: W=50mm, b=20mm, ρ=2mm, t=6mm, E=70GPA, ν=0.33, σntc=80mpa. 101 Figure 57 - KIth(a), KIclose(a), KIfar(a) obtained for the C(T) specimen: W=50mm, b=20mm, ρ=2mm, t=6mm, E=70 GPA, ν=0.33 and σntc=80mpa. 103 Figure 58 - KIth(a), KIclose(a) and the adjusted KIfar(a) in order to obtain σn=slntc for the C(T) specimen: W=50mm, b=20mm, ρ=2mm, t=6mm, E=70 GPA, ν= Figure 59 - KIfar(a) - KIth(a) adjusted in order to obtain σn = SLntc for the C(T) specimen: W=50mm, b=20mm, ρ=2mm, t=6mm, E=70 GPA, ν=

16 Figure 60 - Comparison between finite elements methodology and mixed methodology for the C(T) specimen: W=50mm, b=20mm, ρ=2mm, t=6mm, E=70 GPA, ν=0.33 and σntc=80mpa. Point (2) shows the accurate ast value using the finite element methodology. Points (1) and (3) show incorrect ast values using the mixed methodology. 105 Figure 61 - Graphical comparison showing the ast dependence of notch tip radii, using finite element methodology on a SEN(T) specimens with the following parameters: W=50mm, b=20mm, t=6mm, E=70 GPA, ν=0.33 and σntc 80 MPa. 111

17 List of Tables Table 1 - Crack re-initiation lives Nr after introducing the stop-hole at their tips. 58 Table 2 - Excell spreadsheet showing the closest values for ast based on the difference KI - KIth for a C(T) specimen: W=50mm, b=20mm, ρ=2mm, t=6mm, E=70 GPa, ν=0.33 and σntc = 80MPa. The ast value obtained is equal to 1.297mm. 91 Table 3 - C(T) Specimen s geometry (W, t, b, ρ) and the output parameters Kt, nominal stress on the notch tip σn, the stress on the notch tip σntc = σn Kt and the value of stop crack size (ast). (a) Semiaxis b constant and variable notch tip radius ρ. (b) Notch tip radius ρ constant and variable notch semi-axis b. 107 Table 4 - M(T) Specimen s geometry (W, t, b, ρ) and the output parameters Kt, nominal stress on the notch tip σn, the stress on the notch tip σntc = σn Kt and the value of stop crack size (ast). (a) Semiaxis b constant and variable notch tip radius ρ. (b) Notch tip radius ρ constant and variable notch semi-axis b. 108 Table 5 - SEN(B) Specimen s geometry (W, t, b, ρ) and the output parameters Kt, nominal stress on the notch tip σn, the stress on the notch tip σntc = σn Kt and the value of stop crack size (ast). (a) Semiaxis b constant and variable notch tip radius ρ. (b) Notch tip radius ρ constant and variable notch semi-axis b. 108 Table 6 - SEN(T) Specimen s geometry (W, t, b, ρ) and the output parameters Kt, nominal stress on the notch tip σn, the stress on the notch tip σntc = σn Kt and the value of stop crack size (ast). (a) Semiaxis b constant and variable notch tip radius ρ. (b) Notch tip radius ρ constant and variable notch semi-axis b. 109

18 Table 7 - C(T) Specimen s geometry and the output parameters KtEAC, qeac, applied load P, the threshold nominal stress on the notch tip SLntc, and the stress on the notch tip σntc = SLntc Kt, that leads to a full propagating crack. 112 Table 8 - M(T) Specimen s geometry and the output parameters KtEAC, qeac, applied load P, the threshold nominal stress on the notch tip SLntc, and the stress on the notch tip σntc = SLntc Kt, that leads to a full propagating crack. 113 Table 9 - SEN(B) Specimen s geometry and the output parameters KtEAC, qeac, applied load P, the threshold nominal stress on the notch tip SLntc, and the stress on the notch tip σntc = SLntc Kt, that leads to a full propagating crack. 113 Table 10 - SEN(T) Specimen s geometry and the output parameters KtEAC, qeac, applied load P, the threshold nominal stress on the notch tip SLntc, and the stress on the notch tip σntc = SLntc Kt, that leads to a full propagating crack. 114 Table 11 - Relationship between the output parameters of analysis (Kt, ast, SLntc, KtEAC and qeac), and the geometric variables of the notch and the specimen. 116 Table 12 - C(T) specimen output parameters (Kt, ast, SLntc, KtEAC and qeac) obtained by the mixed methodology and the percentage errors of this methodology. 118 Table 13 - M(T) specimen output parameters (Kt, ast, SLntc, KtEAC and qeac) obtained by the mixed methodology and the percentage errors of this methodology. 118 Table 14 - SEN(B) specimen output parameters (Kt, ast, SLntc, KtEAC and qeac) obtained by the mixed methodology and the percentage errors of this methodology. 119 Table 15 - SEN(T) specimen output parameters (Kt, ast, SLntc, KtEAC and qeac) obtained by the mixed methodology and the percentage errors of this methodology. 119

19 Table 16 - qeac values obtained with the mixed methodology for C(T) specimens, but considering Kt calculated by finite element method. 121 Table 17 - qeac values obtained with the mixed methodology for SEN(T) specimens, but considering Kt calculated by finite element method. 122 Table 18 - qeac values obtained with the mixed methodology for SEN(B) specimens, but considering Kt calculated by finite element method. 122 Table 19 - qeac values obtained with the mixed methodology for M(T) specimens, but considering Kt calculated by finite element method. 123

20 List of Symbols Symbol A Description Crack size a0 Short crack characteristic size at R = 0 a0eac amax Short crack characteristic size under EAC largest non-propagating crack size that can safely arise from a notch ar Short crack characteristic size at R 0 ast b C E g(a/w) Gr Gθmax κ Kf KI(a) KIclose Stop crack size Notch semi-axis Notch semi-axis Young s modulus Yu, Duquesnay and Topper geometric factor Grain size Potential energy release rate Dimensionless factor [ΔK0 / (ΔS0 ρ)] Actual value of the stress concentration factor under fatigue loads Stress intensity factor for mode I, a function of the crack size (a) Stress intensity factor on the notch vicinity KIEAC KIfar KII(a) Resistance to crack propagation under EAC conditions Stress intensity factor far away from the notch vicinity Stress intensity factor for mode II, a function of the crack size (a)

21 KIth(a) Kmáx Kmin Kt KtEAC LT NR P Q qeac R R Rl S Short crack growth threshold, a function of the crack size (a) Maximum value of the stress intensity factor Minimum value of the stress intensity factor Stress concentration factor Actual value of the stress concentration factor under EAC conditions Longitudinal-Transversal specimen cut direction Fatigue re-initiation live Applied load on the test specimens Notch sensitivity factor in fatigue Notch sensitivity factor in EAC (Kmáx / Kmin) ratio Radial coordinate Residual ligament Dimensionless factor (s = a / (a+b)] SEAC Resistance to crack initiation under EAC conditions SLntc SU Sy T Uθmax W Α Γ ΔK ΔK0(a) ΔKI Nominal stress threshold at the notch tip under EAC Ultimate Strenght Yield strength Specimen thickness Strain energy density Specimen s width Peterson s length parameter Bazant s exponent Stress Intensity range Long crack fatigue growth threshold at R = 0, a function of the crack size (a) Range of the stress intensity factor for mode I

22 ΔKth(a) Short crack fatigue threshold, a function of the crack size (a) ΔKth(R=0) = ΔK0 Long crack fatigue growth threshold ar R = 0 ΔS L(R) Range of the fatigue limit at R 0 of standard un-notched specimen and polished specimen ΔS0 Range of the fatigue limit at R = 0 ΔSL Range of the fatigue limit ΔSL(R) = ΔSR Range of the fatigue limit at R 0 Δσ Stress range Δσ0 Stress range at R = 0 Δσ0(a) Δσn Δσth(a) Ε εengu Η Ν Ρ Σ σn σntc σres σy σymáx σθmáx ϕ(a) ϕf Stress range at R = 0, a function of the crack size (a) Nominal stress range at the notch tip Stress range threshold, a function of the crack size (a) Strain Ultimate engineering strength Free surface factor Poisson s ratio Notch tip radius Stress Nominal stress at the notch tip Normal stress at the notch tip Residual stress Stress on y-direction ahead of the notch tip Maximum tensile stress on y-direction Maximum tangential tensile stress Quantification factor of the stress gradient near the notch tip Safety factor

23 List of Acronyms Acronym 1D 2D 3D API ASM ASTM C(T) CRA DCT EAC EDI ETS FCG FE FEM H2S ISO LE LEFM M(T) MCC Morrow EL NACE SIA Description One-Dimensional Two-Dimensional Three-Dimensional American Petroleum Institute American Society for Metals American Society for Testing and Materials Compact Tension specimen Corrosion Resistant Alloy Displacement Correlation Technique Environmentally Assisted Cracking Equivalent Domain Integral El Haddad-Topper-Smith Fatigue Crack Growth Finite Element Finite Element Method Hydrogen Sulfide International Organization for Standarlization Linear Elastic Linear Elastic Fracture Mechanics Middle Notch under Tension specimen Modified Crack-Closure integral Morrow Elastic εn average load effects model National Association of Corrosion Engineers Structural Integrity Assessment

24 SCC SCF SEN(B) SEN(T) SG SIF SMSS SWT TCD TS VAC Stress Corrosion Cracking Stress Concentration Factor Single Edge Notch under Bending specimen Single Edge Notch under Tension specimen Stress Gradient Stress Intensity Factor Super Martensitic Stainless Steel Smith-Watson-Topper εn average load effects model Theory of Critical Distances Test Specimen Subscript denoting Vacuum conditions