ASTM E208-20e1

Standard Test Method for Conducting Drop-Weight Test to Determine Nil-Ductility Transition Temperature of Ferritic Steels

SIGNIFICANCE AND USE
5.1 The fracture-strength transitions of ferritic steels used in the notched condition are markedly affected by temperature. For a given “low” temperature, the size and acuity of the flaw (notch) determines the stress level required for initiation of brittle fracture. The significance of this test method is related to establishing that temperature, defined herein as the NDT temperature, at which the “small flaw” initiation curve, Fig. 1, falls to nominal yield strength stress levels with decreasing temperature, that is, the point marked NDT in Fig. 1.
FIG. 1 Generalized Fracture Analysis Diagram Indicating the Approximate Range of Flaw Sizes Required for Fracture Initiation at Various Levels of Nominal Stress, as Referenced by the NDT Temperature3 , 4  
CAT (crack arrest temperature)–the temperature of arrest of a propagating brittle fracture. CAT curve is thus a stress versus temperature curve as related to crack arrest.
FTE (fracture transition elastic) temperature–the crack arrest temperature for a stress level equal to the yield strength thus marks the highest temperature of fracture propagation for purely elastic loads.
FTP (fracture transition plastic) temperature–the temperature above which fractures are entirely shear, that is, show no center regions of cleavage fracture, and the stress required for fracture approximates the tensile strength of the steel.  
5.2 Interpretations to other conditions required for fracture initiation may be made by the use of the generalized flaw-size, stress-temperature diagram shown in Fig. 1. The diagram was derived from a wide variety of tests, both fracture-initiation and fracture-arrest tests, as correlated with the NDT temperature established by the drop-weight test. Validation of the NDT temperature has been documented by correlations with numerous service failures encountered in ship, pressure vessel, machinery component, forged, and cast steel applications.  
5.3 Lists of Selected References Relating to Develop...
SCOPE
1.1 This test method covers the determination of the nil-ductility transition (NDT) temperature of ferritic steels, 5/8 in. (15.9 mm) and thicker.  
1.2 This test method may be used whenever the inquiry, contract, order, or specification states that the steels are subject to fracture toughness requirements as determined by the drop-weight test.  
1.3 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.  
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 30-Jun-2020
• ICS: 77.040.10 - Mechanical testing of metals
• Technical Committee: E28 - Mechanical Testing
• Drafting Committee: E28.07 - Impact Testing

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
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Designation: E208 − 20
Standard Test Method for
Conducting Drop-Weight Test to Determine Nil-Ductility
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Transition Temperature of Ferritic Steels
This standard is issued under the fixed designation E208; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the U.S. Department of Defense.
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ε NOTE—Footnote 2 was editorially corrected in February 2023.
INTRODUCTION
This drop-weight test was developed at the Naval Research Laboratory in 1952 and has been used
extensively to investigate the conditions required for initiation of brittle fractures in structural steels.
Drop-weight test facilities have been established at several Naval activities, research institutions, and
industrial organizations in this country and abroad. The method is used for specification purposes by
industrial organizations and is referenced in several ASTM specifications and the ASME Boiler and
Pressure Vessel Code. This procedure was prepared to ensure that tests conducted at all locations
would have a common meaning. This test method was originally published as Department of the Navy
document NAVSHIPS-250-634-3.
1. Scope* mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee.
1.1 This test method covers the determination of the nil-
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ductility transition (NDT) temperature of ferritic steels, ⁄8 in.
2. Referenced Documents
(15.9 mm) and thicker.
2.1 ASTM Adjuncts:
1.2 This test method may be used whenever the inquiry,
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Drop-Weight Test Machine
contract, order, or specification states that the steels are subject
to fracture toughness requirements as determined by the
3. Terminology
drop-weight test.
3.1 Definitions of Terms Specific to This Standard:
1.3 The values stated in inch-pound units are to be regarded
3.1.1 ferritic—the word ferritic as used hereafter refers to all
as standard. The values given in parentheses are mathematical
α-Fe steels, including martensitic, pearlitic, and all other
conversions to SI units that are provided for information only
nonaustenitic steels.
and are not considered standard.
3.1.2 nil-ductility transition (NDT) temperature— the maxi-
1.4 This standard does not purport to address all of the
mum temperature where a standard drop-weight specimen
safety concerns, if any, associated with its use. It is the
breaks when tested according to the provisions of this method.
responsibility of the user of this standard to establish appro-
priate safety, health, and environmental practices and deter-
4. Summary of Test Method
mine the applicability of regulatory limitations prior to use.
4.1 The drop-weight test employs simple beam specimens
1.5 This international standard was developed in accor-
specially prepared to create a material crack in their tensile
dance with internationally recognized principles on standard-
surfaces at an early time interval of the test. The test is
ization established in the Decision on Principles for the
conducted by subjecting each of a series (generally four to
Development of International Standards, Guides and Recom-
eight) of specimens of a given material to a single impact load
at a sequence of selected temperatures to determine the
maximum temperature at which a specimen breaks. The impact
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This test method is under the jurisdiction of the ASTM Committee E28 on
load is provided by a guided, free-falling weight with an energy
Mechanical Testing and is the direct responsibility of Subcommittee E28.07 on
Impact Testing.
Current edition approved July 1, 2020. Published July 2020. Originally approved
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in 1963. Last previous edition approved in 2019 as E208 – 19. DOI: 10.1520/ Detail drawings for the construction of this machine are available from ASTM
E0208-20E01. Headquarters. Order ADJE0208-E-PDF. Original adjunct produced in 2002.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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E208 − 20
of 250 to 1400 ft·lbf (340 to 1900 J) depending on the yield derived from a wide variety of tests, both fracture-initiation
strength of the steel to be tested. The specimens are prevented and fracture-arrest tests, as correlated with the NDT tempera-
by a stop from deflecting more than a few tenths of an inch. ture established by the drop-weight test. V
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