Notch-related weakening and strengthening behavior under creep–fatigue conditions was studied in terms of the elastic–viscoplasticity finite-element method (FEM). A coupled damage analysis, i.e., the skeletal point method for creep damage evaluation coupled with the equivalent strain range method for fatigue damage, was employed in the notch effect evaluation. The results revealed that, under the short holding time condition, a weakening behavior was observed for the notch, while a strengthening effect was detected with the increase of holding time. The difference could be ascribed to the creep damage contribution in the holding stage. The influence of stress concentration factor (SCF), stress ratio, and the maximum stress was strongly dependent on the competition of creep and fatigue mechanism.

References

References
1.
Goyal
,
S.
,
Laha
,
K.
,
Das
,
C. R.
,
Panneerselvi
,
S.
, and
Mathew
,
M. D.
,
2014
, “
Effect of Constraint on Creep Behavior of 9Cr-1Mo Steel
,”
Metall. Mater. Trans. A
,
45A
(
2
), pp.
619
632
.
2.
Isobe
,
N.
,
Yashirodai
,
K.
, and
Murata
,
K.
,
2014
, “
Creep Damage Assessment for Notched Bar Specimens of a Low Alloy Steel Considering Stress Multiaxiality
,”
Eng. Fract. Mech.
,
123
, pp.
211
222
.
3.
Yu
,
Q. M.
,
Wang
,
Y. L.
,
Wen
,
Z. X.
, and
Yue
,
Z. F.
,
2009
, “
Notch Effect and Its Mechanism During Creep Rupture of Nickel-Base Single Crystal Superalloys
,”
Mater. Sci. Eng. A
,
520
(1–2), pp.
1
10
.
4.
Hyde
,
T. H.
,
Becker
,
A. A.
,
Song
,
Y.
, and
Sun
,
W.
,
2006
, “
Failure Estimation of TIG Butt-Welded Inco718 Sheets at 620 °C Under Creep and Plasticity Conditions
,”
Comput. Mater. Sci.
,
35
(
1
), pp.
35
41
.
5.
Goyal
,
S.
, and
Laha
,
K.
,
2014
, “
Creep Life Prediction of 9Cr-1Mo Steel Under Multiaxial State of Stress
,”
Mater. Sci. Eng. A
,
615
, pp.
348
360
.
6.
Shi
,
D. Q.
,
Hu
,
X. A.
,
Wang
,
J. K.
, and
Huang
,
J.
,
2013
, “
Effect of Notch on Fatigue Behaviour of a Directionally Solidified Superalloy at High Temperature
,”
Fatigue Fract. Eng. Mater. Struct.
,
36
(
12
), pp.
1288
1297
.
7.
Chen
,
Q.
,
Kawagoishi
,
N.
, and
Nisitani
,
H.
,
1999
, “
Evaluation of Notched Fatigue Strength at Elevated Temperature by Linear Notch Mechanics
,”
Int. J. Fatigue
,
21
(
9
), pp.
925
931
.
8.
Bubphachot
,
B.
,
Watanabe
,
O.
,
Kawasaki
,
N.
, and
Kasahara
,
N.
,
2011
, “
Crack Initiation Process for Semicircular Notched Plate in Fatigue Test at Elevated Temperature
,”
ASME J. Pressure Vessel Technol.
,
133
(
3
), p.
031403
.
9.
Berto
,
F.
,
Gallo
,
P.
, and
Lazzarin
,
P.
,
2014
, “
High Temperature Fatigue Tests of Un-Notched and Notched Specimens Made of 40CrMoV13.9 Steel
,”
Mater. Des.
,
63
, pp.
609
619
.
10.
Sakane
,
M.
,
Ohnami
,
M.
,
Awaya
,
T.
, and
Shirafuji
,
N.
,
1989
, “
Frequency and Hold-Time Effects on Low Cycle Fatigue Life of Notched Specimens at Elevated Temperature
,”
ASME J. Eng. Mater. Technol.
,
111
(
1
), pp.
54
60
.
11.
Huang
,
J.
,
Yang
,
X.
,
Shi
,
D.
,
Yu
,
H.
,
Dong
,
C.
, and
Hu
,
X.
,
2014
, “
Systematic Methodology for High Temperature LCF Life Prediction of Smooth and Notched Ni-Based Superalloy With and Without Dwells
,”
Comput. Mater. Sci.
,
89
, pp.
65
74
.
12.
Ponter
,
A. R. S.
,
Chen
,
H.
,
Willis
,
M. R.
, and
Evans
,
W. J.
,
2004
, “
Fatigue-Creep and Plastic Collapse of Notched Bars
,”
Fatigue Fract. Eng. Mater. Struct.
,
27
(
4
), pp.
305
318
.
13.
Feng
,
L.
, and
Xuan
,
F. Z.
,
2015
, “
Release and Redistribution of Residual Stress in the Welded Turbine Rotor Under Service-Type Loadings
,”
Nucl. Eng. Des.
,
295
, pp.
500
510
.
14.
ASME
,
2015
, “
ASME Boiler and Pressure Vessel Code, III-NH, Class 1 Components in Elevated Temperature Service
,” American Society of Mechanical Engineers, New York.
15.
Jiang
,
Y. P.
,
Guo
,
W. L.
,
Yue
,
Z. F.
, and
Wang
,
J.
,
2006
, “
On the Study of the Effects of Notch Shape on Creep Damage Development Under Constant Loading
,”
Mater. Sci. Eng. A
,
437
(
2
), pp.
340
347
.
16.
Jiang
,
Y. P.
,
Guo
,
W. L.
, and
Yue
,
Z, F.
,
2007
, “
On the Study of the Creep Damage Development in Circumferential Notch Specimens
,”
Comput. Mater. Sci.
,
38
(
4
), pp.
653
659
.
17.
Xu
,
X.
,
Wang
,
G. Z.
,
Xuan
,
F. Z.
, and
Tu
,
S. T.
,
2016
, “
Effects of Creep Ductility and Notch Constraint on Creep Fracture Behavior in Notched Bar Specimens
,”
Mater. High Temp.
,
33
(
2
), pp.
198
207
.
18.
Telesman
,
J.
,
Gabb
,
T. P.
,
Ghosn
,
L. J.
, and
Gayda
,
J.
,
2016
, “
Effect of Notches on Creep-Fatigue Behavior of a P/M Nickel-Based Superalloy
,”
Int. J. Fatigue
,
87
, pp.
311
325
.
19.
Nix
,
W. D.
,
Earthman
,
J. C.
,
Eggeler
,
G.
, and
IIschner
,
B.
,
1989
, “
The Principal Facet Stress as a Parameter for Predicting Creep Rupture Under Multiaxial Stresses
,”
Acta Metall.
,
37
(
4
), pp.
1067
1077
.
20.
Webster
,
G. A.
,
Holdsworth
,
S. R.
,
Loveday
,
M. S.
,
Nikbin
,
K.
,
Perrin
, I
. J.
,
Purper
,
H.
,
Skelton
,
R. P.
, and
Spindler
,
M. W.
,
2004
, “
A Code of Practice for Conducting Notched Bar Creep Tests and for Interpreting the Data
,”
Fatigue Fract. Eng. Mater. Struct.
,
27
(
4
), pp.
319
342
.
21.
Hayhurst
,
D. R.
,
1972
, “
Creep Rupture Under Multi-Axial States of Stress
,”
J. Mech. Phys. Solids
,
20
(
6
), pp.
381
382
.
22.
Cane
,
B. J.
,
1981
, “
Creep Damage Accumulation and Fracture Under Multiaxial Stresses
,”
ICF5
, Cannes, France, pp.
1285
1293
.
23.
Dassault Systems
,
2011
, Abaqus 6.11 User's
Manual, Dassault Systems SIMULIA
,
Providence, RI
.
24.
Wu
,
D. L.
,
Zhao
,
P.
,
Wang
,
Q. Q.
, and
Xuan
,
F. Z.
,
2015
, “
Cyclic Behavior of 9–12% Cr Steel Under Different Control Modes in Low Cycle Regime: A Comparative Study
,”
Int. J. Fatigue
,
70
, pp.
114
122
.
25.
Wu
,
D. L.
,
Xuan
,
F. Z.
,
Guo
,
S. J.
, and
Zhao
,
P.
,
2016
, “
Uniaxial Mean Stress Relaxation of 9–12% Cr Steel at High Temperature: Experiments and Viscoplastic Constitutive Modeling
,”
Int. J. Plast.
,
77
, pp.
156
173
.
You do not currently have access to this content.