For modern plate steels exhibiting high toughness and ductility, the conventional Charpy test is ostensibly stretched beyond its limits of applicability. Impact tests yield absorbed energy values in excess of 300–400 J, which are associated with limited material fracture and mostly derive from plastic deformation of the specimen (bending), friction, and vibrations of the swinging hammer. It would be therefore very desirable to measure the actual fracture toughness of very-high-toughness steels by means of an alternative specimen and/or methodology, entailing just a moderate increase of cost and test complexity with respect to Charpy testing. The investigation presented here was aimed at establishing a reasonable, yet cost-effective test procedure utilizing Charpy-type specimens for measuring the dynamic toughness of high-toughness steels, such as line pipe steels. Promising results have been obtained from notches cut by electrical-discharge machining (EDM) using a thin wire of 0.1 mm diameter, as compared to specimens where an actual crack was generated and propagated by fatigue at the root of the machined notch.

References

References
1.
McCowan
,
C. N.
,
Lucon
,
E.
, and
Santoyo
,
R. L.
,
2011
, “
Evaluation of the Energy Absorbed in Charpy Tests at 100 J Versus 300 J
,”
International Symposium on the Recent Developments in Plate Steels
, Winter Park, CO, June 19–22.
2.
ASTM
, 2016, “
Standard Test Methods for Notched Bar Impact Testing of Metallic Materials
,”
ASTM International
,
West Conshohocken, PA
, Standard No.
ASTM E23-16b
.
3.
ASTM
, 2017, “
Standard Test Method for Measurement of Fracture Toughness
,”
ASTM International
,
West Conshohocken, PA
, Standard No.
ASTM E1820-17
.
4.
McCowan
,
C. N.
,
Siewert
,
T. A.
, and
Vigliotti
,
D. P.
,
2003
, “
Charpy Verification Program: Reports Covering 1989-2002
,” Materials Reliability Series, National Institute of Standards and Technology, Boulder, CO, NIST Technical Note No. 1500-9.
5.
Service Steel Aerospace
,
2016
, “
Maraging—Data Sheet
,” Service Steel Aerospace Corp., Seattle, WA, accessed Jan. 30, 2017, http://www.ssa-corp.com/documents/Data%20Sheet%20Maraging.pdf
6.
API
,
2012
, “
API Specification 5 L, Specification for Line Pipe
,”
45th ed.
,
American Petroleum Institute
,
Washington, DC
.
7.
ISO
,
2015
, “
Steel—Charpy V-Notch Pendulum Impact Test—Instrumented Test Method
,” International Standards Organization, Geneva, Switzerland, Standard No.
ISO 14556
.https://www.iso.org/standard/23982.html
8.
ASTM
, 2015, “
Standard Test Method for Impact Testing of Miniaturized Charpy V-Notch Specimens
,” ASTM International, West Conshohocken, PA, Standard No.
ASTM E2248-15
.
9.
Smith
,
E.
, and
Patchett
,
B. M.
,
1975
, “
Effects of Notch Acuity and Side Grooving on Fracture Toughness—Part II: Slow Bend
,”
Weld. Res. Suppl.
, pp.
226s
233s
.http://files.aws.org/wj/supplement/WJ_1975_07_s226.pdf
10.
Zuo
,
J.
,
Deng
,
X.
,
Sutton
,
M. A.
, and
Cheng
,
C.-S.
,
2004
, “
Crack Tunneling: Effect of Stress Constraint
,”
ASME
Paper No. IMECE2004-60700.
11.
ISO,
2015
, “
Metallic Materials—Measurement of Fracture Toughness at Impact Loading Rates Using Precracked Charpy-Type Test Pieces
,” International Standards Organization, Geneva, Switzerland, Standard No. ISO
26843
.https://www.iso.org/standard/65516.html
12.
Wallin
,
K.
, and
Laukkanen
,
A.
,
2004
, “
Improved Crack Growth Corrections for J-R Curve Testing
,”
Eng. Fract. Mech.
,
71
(11), pp.
1601
1614
.
13.
Server
,
W. L.
, and
Ireland
,
D. R.
,
1974
, “
Nonstandard Test Techniques Utilizing the Instrumented Charpy and Izod Tests
,”
American Society for Testing and Materials
,
Philadelphia PA
, Standard No.
ASTM STP 563
.https://www.astm.org/DIGITAL_LIBRARY/STP/PAGES/STP32186S.htm
14.
Jolley
,
G.
,
Kilpatrick
,
I. M.
, and
Main
,
R.
,
1973
, “
Effect of Notch Acuity on the Fracture Toughness of Three Low Alloy High Yield Strength Steels
,”
Weld. Res. Suppl.
, pp.
543s
548s
.http://files.aws.org/wj/supplement/WJ_1973_12_s543.pdf
15.
Clarke
,
G. A.
,
Landes
,
J. D.
, and
Begley
,
J. A.
,
1980
, “
Results of an ASTM Cooperative Test Program on the JIc Determination of HY130 Steel
,”
J. Test. Eval.
,
8
(
5
), pp.
221
232
.
16.
Paris
,
P. C.
,
Tada
,
H.
,
Zahoor
,
A.
, and
Ernst
,
H.
,
1977
, “
A Treatment of the Subject of Tearing Instability
,” U.S. Nuclear Regulatory Commission, Washington, DC, Report No. NUREG-0311.
17.
Li
,
C.-J.
,
1999
, “
Effects of Temperature and Loading Rate on Fracture Toughness of Structural Steels
,”
Mater. Des.
,
21
(
1
), pp.
27
30
.
18.
Wiesner
,
C. S.
, and
MacGillivray
,
H.
,
1999
, “
Loading Rate Effects on Tensile Properties and Fracture Toughness of Steel
,”
TAGSI Seminar on Fracture, Plastic Flow and Structural Integrity
, Cambridge, UK, Apr. 29.https://www.twi-global.com/technical-knowledge/published-papers/loading-rate-effects-on-tensile-properties-and-fracture-toughness-of-steel-april-1999/
19.
Irwin
,
G. R.
,
1948
, “
Fracture Dynamics
,”
Fracturing of Metals
,
American Society for Metals
,
Cleveland, OH
.
20.
Miedlar
,
P. C.
,
Berens
,
A. P.
,
Gunderson
,
A.
, and
Gallagher
,
J. P.
,
2002
, “
USAF Damage Tolerant Design Handbook: Guidelines for the Analysis and Design of Damage Tolerant Aircraft Structures
,” University of Dayton Research Institute, Dayton, OH.
21.
Nguyen-Duy
,
P.
,
1981
, “
Relationship Between Critical Stretch Zone Width, Crack-Tip Opening Displacement, and Fracture-Energy Criterion: Application to SA-516-70 Steel Plates
,” American Society for Testing and Materials, Philadelphia, PA, Standard No.
ASTM STP 743
.https://www.astm.org/DIGITAL_LIBRARY/STP/PAGES/STP28817S.htm
22.
Doig
,
P.
,
Smith
,
R. F.
, and
Flewitt
,
P. E. J.
,
1984
, “
The Use of Stretch Zone Width Measurements in the Determination of Fracture Toughness of Low Strength Steels
,”
Eng. Fract. Mech.
,
19
(
4
), pp.
653
664
.
You do not currently have access to this content.