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Displaying 1 - 25 of 66

OVERVIEW OF NIST ACTIVITIES ON SUB-SIZE AND MINIATURIZED CHARPY SPECIMENS: CORRELATIONS WITH FULL-SIZE SPECIMENS AND VERIFICATION SPECIMENS FOR SMALL-SCALE PENDULUM MACHINES

July 19, 2015
Author(s)
Enrico Lucon, Christopher N. McCowan, Raymond L. Santoyo
NIST in Boulder Colorado investigated the correlations between impact test results obtained from standard, full-size Charpy specimens (CVN) and specimens with reduced thickness (sub-size Charpy specimens, SCVN) or reduced or scaled cross-section dimensions

CTOA Testing of Pipeline Steels Using MDCB Specimens

September 1, 2013
Author(s)
Robert L. Amaro, Jeffrey W. Sowards, Elizabeth S. Drexler, Joseph D. McColskey, Christopher N. McCowan
Crack tip opening angle (CTOA) is used to rank the relative resistance to crack extension of various pipeline steels. In general, the smaller the CTOA value, the lower the resistance to crack extension. It is unclear, however, whether CTOA is a material

Ductile-Fracture Resistance in X100 Pipeline Welds Measured with CTOA

December 1, 2011
Author(s)
Elizabeth S. Drexler, Philippe P. Darcis, Christopher N. McCowan, Jeffrey W. Sowards, Joseph D. McColskey, Thomas A. Siewert
A test for evaluation of resistance to ductile fracture (crack tip opening angle, CTOA) was found to reveal changes in crack propagation through the strain and strength gradients near weld joints in X100 pipeline steels. This test provides a long ligament

Impact Testing - Yesterday and Today

November 13, 2011
Author(s)
Enrico Lucon, Christopher N. McCowan
The Charpy impact test is a standardized high strain rate mechanical test which determines the amount of energy absorbed by a material during impact fracture. This test is widely applied in industry, since it is easy to prepare and conduct, and results can

Fracture of X100 Pipeline Steel: Combined Experimental-Numerical Process

August 26, 2011
Author(s)
Mordechai Szanto, Christopher N. McCowan, Elizabeth S. Drexler, Joseph D. McColskey
Accurate characterization of material fracture properties is necessary for reliable numerical prediction of rupture in gas pipelines. In the current work the ductile fracture properties for high strength X100 pipeline steel, was evaluated, using

Evaluation of Bias for Two Charpy Impact Machines Using the Same Instrumented Striker

May 1, 2011
Author(s)
Christopher N. McCowan, Enrico Lucon, Raymond L. Santoyo
Two Charpy machines were used to test NIST verification specimens at three energy levels: low energy (≈ 15 J at -40°C), high energy (≈ 100 J at -40°C) and super-high energy (≈ 240 J at room temperature). The study evaluates the differences observed for the

United States Capitol Dome:Characterization of Cast and Wrought Materials

January 2, 2011
Author(s)
Christopher N. McCowan, Thomas A. Siewert, David Olson, Joseph D. McColskey
Restoration of the cast iron dome at the United States Capitol is needed because moisture is leaking into interior areas of the building due to corrosion damage. Microstructure, composition, and tensile properties of cast and wrought samples from the dome

MEASUREMENT OF CTOA OF PIPE STEELS USING MDCB AND DWTT SPECIMENS

September 27, 2010
Author(s)
Christopher N. McCowan, S. Xu, W. R. Tyson, R. Eagleson, Elizabeth S. Drexler, J. D. McColskey, Philippe P. Darcis
Two types of specimen for crack tip opening angle (CTOA)measurement have been investigated for pipeline applications,i.e., the modified double cantilever beam (MDCB) (at NIST)and the drop-weight tear test (DWTT) specimen (at CANMET). Results of effects of

Certification Report for SRM 2112 and 2113

July 1, 2009
Author(s)
Christopher N. McCowan
This report documents the procedures used to develop certified maximum force and absorbed energy values for SRM 2112 and SRM 2113. The report serves to provide outside observers with accurate and detailed information on how the materials were certified and

Crack tip opening angle: applications and developments in the pipeline industry

July 1, 2009
Author(s)
Elizabeth S. Drexler, Philippe Darcis, Richard J. Fields, Joseph D. McColskey, Christopher N. McCowan, Roni Reuven, Thomas A. Siewert
One of the most difficult safety problems associated with gas pipeline to be solved is the control of ductile fracture propagation. To address this issue, the crack tip opening angle (CTOA) criterion is becoming one of the more widely accepted properties

Summary of Charpy Impact Verificaiton Data: 1994-1996

March 2, 2009
Author(s)
Christopher N. McCowan, C M. Wang, D P. Vigliotti
We present a summary of Charpy impact verification test data that were evaluated by the National Institute of Standards and Tecnology (NIST) from January 1994 to December 1996. The Charpy impact machines that met the verification rule that limits the range

Instrumented Impact Test: Impact Machine Variables and Specimen Position

January 5, 2009
Author(s)
Christopher N. McCowan
An investigation has been conducted on the influence of impact machine variables and specimen positioning on characteristic forces and absorbed energies from instrumented Charpy tests. Brittle and ductile fracture behavior has been investigated by testing

Instrumented Impact Tests: Effects of Machine Variables and Specimen Position

January 1, 2009
Author(s)
Christopher N. McCowan, Enrico Lucon
An investigation has been conducted on the influence of impact machine variables and specimen positioning on characteristic forces and absorbed energies from instrumented Charpy tests. Brittle and ductile fracture behavior has been investigated by testing

CTOA Measurements of Welds in X100 Pipeline Steel

October 3, 2008
Author(s)
Elizabeth S. Drexler, Philippe P. Darcis, Christopher N. McCowan, John M. Treinen, Avigdor Shtechman, Roni Reuven, Thomas A. Siewert, Robert Smith, J. Merritt, Joseph D. McColskey
A suite of tests characterizing X100 pipeline steels was initiated at the National Institute of Standards and Technology (NIST) in Boulder. Part of the test matrix included testing the toughness of the base metal, welds, and heat-affected zones (HAZ) using

Charpy Machine Verification: Limits and Uncertainty

September 1, 2008
Author(s)
Jolene Splett, Christopher N. McCowan, Chih-Ming Wang
The purpose of this document is to clarify some issues pertaining to uncertainty statements and the ASTM E 23 limits used in the Charpy machine verification program. We explain some of the distributional subtleties associated with uncertainty and

CTOA Results for X65 and X100 Pipeline Steels:Influence of Displacement Rate

August 1, 2008
Author(s)
Roni Reuven, Christopher N. McCowan, Elizabeth S. Drexler, Avigdor Shtechman, Philippe P. Darcis, John M. Treinen, R. Smith, J. Merritt, Thomas A. Siewert, Joseph D. McColskey
The toughness and plasticity of steel generally decreases with increasing testing rate. The crack tip opening angle (CTOA) was measured on two types of commercial pipeline steels, API-X65 and API-X100 at a range of displacement rates to characterize rate