A series of single-edge notched tension (SENT or SE(T)) and single-edge notched bend (SENB or SE(B)) testing was carried out at −15 °C using B × B specimens machined from two API X70 large diameter pipeline girth welds. An initial notch was placed either on the heat-affected zone (HAZ) or the weld metal center from the outer diameter side of pipe to simulate a circumferential surface flaw. SE(T) and SE(B) tests were performed according to the CANMET procedure and ASTM E1820, respectively. For all HAZ SE(B) specimens machined from one pipe, ductile cracks initially propagated away from the fusion line and toward the base metal side due to asymmetric deformation, and then pop-in (i.e., the initiation and arrest of a brittle crack) occurred after ductile crack growth of approximately 1 mm, where the crack reached around the intercritical heat-affected zone. HAZ SE(T) specimens also showed that the ductile crack propagation deviated toward the base metal side, but an unstable brittle crack extension was not observed from any SE(T) specimens as opposed to SE(B) specimens. None of the weld metal SE(T) and SE(B) specimens showed pop-in or brittle fracture at −15 °C or room temperature. The difference in test results, for the same material, is associated with the different constraint levels in the two loading modes, taking into account that pop-ins were triggered in high-constraint SE(B) tests, while it was not the case for low-constraint SE(T) tests.

References

References
1.
CSA
,
2011
, “
Oil & Gas Pipeline Systems
,”
CSA Group
, Toronto, ON, Canada, Standard No. CSA Z662-11.
2.
API
,
2013
, “
Welding of Pipelines and Related Facilities
,” American Petroleum Institute, Washington, DC,
API Standard No. 1104
.
3.
BS
,
2013
, “
Guide to Methods for Assessing the Acceptability of Flaws in Metallic Structures
,” British Standard Institution, London, UK,
Standard No. BS 7910:2013
.
4.
ASTM
,
2011
, “
Standard Test Method for Measurement of Fracture Toughness
,”
ASTM International
, West Conshohocken, PA, Standard No. ASTM E1820-11.
5.
Shen
,
G.
,
Bouchard
,
R.
,
Gianetto
,
J. A.
, and
Tyson
,
W. R.
,
2008
, “
Fracture Toughness Evaluation of High Strength Steel Pipe
,”
ASME
Paper No. PVP2008-61100.
6.
Rivera
,
S.
,
Lezcano
,
R.
,
Rodriguez
,
C.
,
Belzunce
,
F. J.
, and
Betegon
,
C.
,
2012
, “
Effect of Constraint on the Fracture Behaviour of a Simulated Heat-Affected Zone of an X-70 Steel Used in Pipelines
,”
Strain
,
48
(
2
), pp.
157
161
.
7.
Park
,
D. Y.
,
Tyson
,
W. R.
,
Gianetto
,
J. A.
,
Shen
,
G.
, and
Eagleson
,
R. S.
,
2010
, “
Evaluation of Fracture Toughness of ×100 Pipe Steel Using se(b) and Clamped se(t) Single Specimens
,”
ASME
Paper No. IPC2010-31282.
8.
Shen
,
G.
,
Gianetto
,
J. A.
, and
Tyson
,
W. R.
,
2008
, “
Development of Procedure for Low-Constraint Toughness Testing Using a Single-Specimen Technique
,” CANMET Materials Technology Laboratory, Technical Report No. 2008-18 (TR).
9.
Tang
,
H.
,
Macia
,
M.
,
Minnaar
,
K.
,
Gioielli
,
P.
,
Kibey
,
S.
, and
Fairchild
,
D.
,
2010
, “
Development of the SENT Test of Strain-Based Design of Welded Pipelines
,” 8th International Pipeline Conference (IPC 2010), Calgary, AB, Canada, Sept. 27–Oct. 1.
10.
Park
,
D. Y.
,
Gravel
,
J. P.
,
Arafin
,
M.
,
Liang
,
J.
, and
Simha
,
C. H. M.
,
2015
, “
Evaluation of Two Low-Constraint Toughness Test Methods in a Single Specimen
,”
ASME J. Eng. Mater. Technol.
,
137
(
1
), pp.
011003-1
011003-9
.
11.
Park
,
D. Y.
,
Gravel
,
J. P.
,
Simha
,
C. H. M.
,
Liang
,
J.
, and
Duan
,
D. M.
,
2014
, “
Fracture Toughness of X70 Pipe Girth Welds Using Clamped SE(T) and SE(B) Single-Specimens
,”
ASME
Paper No. IPC2014-33233.
12.
Park
,
D. Y.
,
Gravel
,
J. P.
,
Simha
,
C. H. M.
,
Liang
,
J.
, and
Duan
,
D. M.
,
2014
, “
Low-Constraint Toughness Testing of Two SE(T) Methods in a Single Specimen
,”
ASME
Paper No. PVP2014-28415.
13.
BS
,
2014
, “
Method of Test for Determination of Fracture Toughness in Metallic Materials Using Single Edge Notched Tension (SENT) Specimens
,” British Standards Institution, London, UK, Standard No. BS 8571:2014.
14.
Park
,
D. Y.
, and
Gravel
,
J. P.
,
2015
, “
Fracture Toughness Measurements Using Two Single-Edge Notched Bend Test Methods in a Single Specimen
,”
Eng. Fract. Mech.
,
144
, pp.
78
88
.
15.
Anderson
,
T. L.
,
2005
,
Fracture Mechanics—Fundamentals and Applications
,
Taylor & Francis Group LLC
, Boca Raton, FL.
16.
Xu
,
S.
,
Eagleson
,
R.
,
Tyson
,
W. R.
, and
Park
,
D. Y.
,
2011
, “
Crack Tunnelling and Crack Tip Opening Angle in Drop-Weight Tear Test Specimens
,”
Int. J. Fract.
,
172
(
1
), pp.
105
112
.
17.
Alé
,
R. M.
,
Rebello
,
J. M. A.
, and
Charlier
,
J.
,
1996
, “
A Metallographic Technique for Detecting Martensite-Austenite Constituents in the Weld Heat-Affected Zone of a Micro-Alloyed Steel
,”
Mater. Charact.
,
37
(2–3), pp.
89
93
.
18.
Andia
,
J. L. M.
,
de Souza
,
L. F. G.
, and
Bott
,
I. S.
,
2013
, “
HAZ Physical Simulation of API 5L X80 Pipeline Steel
,”
8th Pipeline Technology Conference
, Hannover, Germany, Mar. 18–20.
19.
Bhadeshia
,
H. K. D. H.
,
2013
, “
About Calculating the Characteristics of the Martensite-Austenite Constituent
,”
International Seminar on Welding of High Strength Pipeline Steels
,
CBMM and TMS
, Araxa, Brazil, Nov. 28–30, pp.
99
106
.
20.
Mohseni
,
P.
,
Solberg
,
J. K.
,
Karlsen
,
M.
,
Akselsen
,
O. M.
, and
Østby
,
E.
,
2012
, “
Investigation of Mechanism of Cleavage Fracture Initiation in Intercritically Coarse Grained Heat Affected Zone of HSLA Steel
,”
Mater. Sci. Technol. (U. K.)
,
28
(
11
), pp.
1261
1268
.
21.
Shin
,
S.
,
Hwang
,
B.
,
Kim
,
S.
, and
Lee
,
S.
,
2006
, “
Fracture Toughness Analysis in Transition Temperature Region of API X70 Pipeline Steels
,”
Mater. Sci. Eng.: A
,
429
(1–2), pp.
196
204
.
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