ASTM E208-95a(2000)e1
(Test Method)Standard Test Method for Conducting Drop-Weight Test to Determine Nil-Ductility Transition Temperature of Ferritic Steels
Standard Test Method for Conducting Drop-Weight Test to Determine Nil-Ductility Transition Temperature of Ferritic Steels
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 the standard.
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 and health practices and determine the applicability of regulatory limitations prior to use.
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Designation:E208–95a(Reapproved 2000)
Standard Test Method for
Conducting Drop-Weight Test to Determine Nil-Ductility
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.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the Department of Defense.
e NOTE—Adjunct references were corrected editorially in April 2006.
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.
1. Scope 3.1.1 ferritic—the word ferritic as used hereafter refers to
all a-Fe steels. This includes martensitic, pearlitic, and all
1.1 This test method covers the determination of the nil-
5 other nonaustenitic steels.
ductility transition (NDT) temperature of ferritic steels, ⁄8 in.
3.1.2 nil-ductility transition (NDT) temperature—themaxi-
(15.9 mm) and thicker.
mum temperature where a standard drop-weight specimen
1.2 This test method may be used whenever the inquiry,
breaks when tested according to the provisions of this method.
contract,order,orspecificationstatesthatthesteelsaresubject
to fracture toughness requirements as determined by the
4. Summary of Test Method
drop-weight test.
4.1 The drop-weight test employs simple beam specimens
1.3 Thevaluesstatedininch-poundunitsaretoberegarded
specially prepared to create a material crack in their tensile
as the standard.
surfaces at an early time interval of the test. The test is
1.4 This standard does not purport to address all of the
conducted by subjecting each of a series (generally four to
safety concerns, if any, associated with its use. It is the
eight) of specimens of a given material to a single impact load
responsibility of the user of this standard to establish appro-
at a sequence of selected temperatures to determine the
priate safety and health practices and determine the applica-
maximumtemperatureatwhichaspecimenbreaks.Theimpact
bility of regulatory limitations prior to use.
loadisprovidedbyaguided,free-fallingweightwithanenergy
2. Referenced Documents of 250 to 1200 ft-lbf (340 to 1630 J) depending on the yield
strength of the steel to be tested. The specimens are prevented
2.1 ASTM Adjuncts:
by a stop from deflecting more than a few tenths of an inch.
Drop Weight Machine
4.2 The usual test sequence is as follows: After the prepa-
3. Terminology
rationandtemperatureconditioningofthespecimen,theinitial
drop-weighttestisconductedatatesttemperatureestimatedto
3.1 Definitions:
be near the NDT temperature. Depending upon the results of
the first test, tests of the other specimens are conducted at
This test method is under the jurisdiction of the ASTM Committee E28 on
suitable temperature intervals to establish the limits within
Mechanical Testing and is the direct responsibility of Subcommittee E28.07 on
10°F (5°C) for break and no-break performance. A duplicate
Impact Testing.
Current edition approved Aug. 15, 1995. Published October 1995. Originally
test at the lowest no-break temperature of the series is
published as E208–63T. Last previous edition E208–95.
conducted to confirm no-break performance at this tempera-
Detail drawings for the construction of this machine are available fromASTM
ture.
Headquarters. Order ADJE0208. Original adjunct produced in 2002.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
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E208–95a (2000)
4.3 In 1984, the method of applying the crack-starter weld 6.2 Arail, or rails, rigidly held in a vertical position and in
bead was changed from a two-pass technique to the current a fixed relationship to the base shall be provided to guide the
single-passprocedure,andthepracticeofrepair-weldingofthe weight. The weight shall be provided with suitable devices
crack-starter weld bead was prohibited. For steels whose which engage the rail, or rails, and ensure that it will drop
properties are influenced by tempering or are susceptible to
freely in a single, vertical plane. The weight may be raised by
temper embrittlement, the nil-ductility transition (NDT) tem- any convenient means.Aweight-release mechanism, function-
peratureobtainedusingthesingle-passcrack-starterweldbead
ing similarly to that shown in Fig. 2( b), shall be provided to
may not agree with that obtained using the previous two-pass release the weight quickly without affecting its free fall. The
crack-starter weld bead, or when the crack-starter bead was
weightshallbemadeinonepiece,orifmadeofseveralpieces,
repaired. its construction shall be rigid to ensure that it acts as a unit
when it strikes the specimen. The striking tup of the weight
5. Significance and Use
shall be a steel cylindrical surface with a radius of 1 in. (25.4
5.1 Thefracture-strengthtransitionsofferriticsteelsusedin
mm) and a minimum hardness of HRC 50 throughout the
the notched condition are markedly affected by temperature.
section. The weight shall be between 50 and 300 lb (22.7 and
For a given “low” temperature, the size and acuity of the flaw
136 kg). The rails and hoisting device shall permit raising the
(notch) determines the stress level required for initiation of
weight various fixed distances to obtain potential energies of
brittlefracture.Thesignificanceofthistestmethodisrelatedto
250 to 1200 ft-lbf (340 to 1630 J).
establishing that temperature, defined herein as the NDT
6.3 Ahorizontalbase,locatedundertheguiderails,shallbe
temperature, at which the “small flaw” initiation curve, Fig. 1,
provided to hold and position precisely the several styles of
falls to nominal yield strength stress levels with decreasing
anvils required for the standard specimens. The anvil guides
temperature, that is, the point marked NDT in Fig. 1.
shall position the anvil with the center-line of the deflection
5.2 Interpretations to other conditions required for fracture
stops under the center-line of the striking tup of the weight. In
initiation may be made by the use of the generalized flaw-size,
general,thebasewillalsosupporttheguiderails,butthisisnot
stress-temperature diagram shown in Fig. 1. The diagram was
a requirement. The base shall rest on the rigid foundation. The
derived from a wide variety of tests, both fracture-initiation
base-foundation system shall be sufficiently rigid to allow the
and fracture-arrest tests, as correlated with the NDT tempera-
normal drop-weight energy (Table 1) to deflect a standard
tureestablishedbythedrop-weighttest.ValidationoftheNDT
specimen to the stop at temperatures above the NDT.The base
concept has been documented by correlations with numerous
shall not jump or shift during the test, and shall be secured to
servicefailuresencounteredinship,pressurevessel,machinery
the foundation if necessary to prevent motion.
component, forged, and cast steel applications.
6.4 A guard screen, similar to that shown in Fig. 2(c), is
6. Apparatus
recommended to stop broken specimen halves of the very
brittle steels which break into two pieces with both halves
6.1 The drop-weight machine is of simple design based on
being ejected forcefully from the machine.
the use of readily available structural steel products. The
principalcomponentsofadrop-weightmachineareavertically 6.5 The general characteristics of two of the anvils required
guided,free-fallingweight,andarigidlysupportedanvilwhich areillustratedinFig.3.Theanvilsshallbemadeinaccordance
provides for the loading of a rectangular plate specimen as a with the dimensions shown in Fig. 4. The anvil supports and
simple beam under the falling weight. Fig. 2(a) illustrates a deflectionstopsshallbesteel-hardenedtoaminimumhardness
typical drop-weight machine built of standard structural of HRC 50 throughout their cross section. The space between
shapes. thetwostopsisprovidedasclearanceforthecrack-starterweld
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 Temperature
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E208–95a (2000)
(a) Left—Complete Assembly
(b) Upper Right—Quick Release Mechanism
(c) Lower Right—Guard Screen
FIG. 2 Drop-Weight Test Apparatus
TABLE 1 Standard Drop-Weight Test Conditions
Drop-Weight Energy for Given
A
Specimen Size, Deflection Stop, Yield Strength Level,
Yield Strength Level
Type of Specimen Span, in. (mm)
in. (mm) in. (mm) ksi (MPa)
ft-lbf J
P-1 1 by 3 ⁄2 by 14 12.0 0.3 30 to 50 (210 to 340) 600 800
(25.4 by 89 by 356) (305) (7.6) 50 to 70 (340 to 480) 800 1100
70 to 90 (480 to 620) 1000 1350
90 to 110 (620 to 760) 1200 1650
P-2 ⁄4 by2by5 4.0 0.06 30 to 60 (210 to 410) 250 350
(19 by 51 by 127) (102) (1.5) 60 to 90 (410 to 620) 300 400
90 to 120 (620 to 830) 350 450
120 to 150 (830 to 1030) 400 550
P-3 ⁄8 by2by5 4.0 0.075 30 to 60 (210 to 410) 250 350
(15.9 by 51 by 127) (102) (1.9) 60 to 90 (410 to 620) 300 400
90 to 120 (620 to 830) 350 450
120 to 150 (830 to 1030) 400 550
A
Initial tests of a given strength level steel shall be conducted with the drop-weight energy stated in this column. In the event that insufficient deflection is developed
(no-test performance) an increased drop-weight energy shall be employed for other specimens of the given steel.
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E208–95a (2000)
FIG. 3 General Appearance of the Anvils Required for Drop-Weight NDT Tests
on the specimen. The deflection stops may be made in two zone created by deposition of the crack-starter weld is made
separate pieces, if desired. The anvil-base system shall be morefractureresistantthantheunaffectedplate.Thiscondition
sufficiently rigid to allow the normal drop-weight energy is developed for quenched and tempered steels of high hard-
(Table 1) to deflect the specimen to the stop at temperatures ness obtained by tempering at low temperatures. The problem
well above the NDT. may be avoided by placing the crack-starter weld on these
6.6 Ameasuring system shall be provided to assure that the steels before conducting the quenching and tempering heat
weight is released from the desired height for each test, within treatment. Except for other cases which may be readily
the limits of+10, −0%. rationalized in metallurgical terms (for example, it is possible
6.7 Modifications of the equipment or assembly details of to recrystallize heavily cold-worked steels in the heat-affected
the drop-weight machine shown in Fig. 2 are permitted zone and to develop a region of improved ductility), the
provided that the modified machine is functionally equivalent. heat-affected zone problem is not encountered with conven-
Fig. 5 illustrates a portable machine design used by an tional structural grade steels of a pearlitic microstructure or
industrial concern for drop-weight tests of materials used for quenchedandtemperedsteelstemperedathightemperaturesto
pressure vessel components at different fabrication sites. develop maximum fracture toughness.
7. Precautions 8. Test Specimens
7.1 Thedrop-weighttestwasdevisedformeasuringfracture 8.1 Identification of Material—All sample material and
initiation characteristics of ⁄8-in. (15.9-mm) and thicker struc- specimens removed from a given plate, shape, forging, or
tural materials. This test is not recommended for steels less casting product shall be marked to identify their particular
than ⁄8-in. thick. source(heatnumber,slabnumber,etc.).Asimpleidentification
7.2 This test method establishes standard specimens and system shall be used which can be employed in conjunction
conditions to determine the NDT temperature of a given steel. with an itemized table to obtain all the pertinent information.
The use of standard specimens with nonstandard test condi- 8.2 Orientation—The drop-weight test is insensitive to
tions or the use of nonstandard specimens shall not be allowed specimen orientation with respect to rolling or forging direc-
for specification purposes. tion. However, unless otherwise agreed to, all specimens
7.3 This test method employs a small weld bead deposited specified by the purchaser shall be of the same orientation and
on the specimen surface, whose sole purpose is to provide a it shall be noted in the test report.
brittlematerialfortheinitiationofasmall,cleavagecrack-flaw 8.3 Relation to Other Specimens—Unless otherwise speci-
in the specimen base material during the test. Anomalous fiedbythepurchaser,thespecimensshallberemovedfromthe
behaviormaybeexpectedformaterialswheretheheat-affected material at positions adjacent to the location of other type test
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E208–95a (2000)
Specimen Type
Anvil Dimension Units Tolerance
P-1 P-2 P-3
S, Span in. 12.0 4.0 4.0 60.05
mm 305 100 100 61.5
D, Deflection stop in. 0.30 0.060 0.075 60.002
mm 7.60 1.50 1.90 60.05
A, Anvil length ←——————––not critical––——————→
B, Anvil width ←——————––not critical––——————→
C, Anvil thickness in. 1.5 min 1.5 min 1.5 min
mm 38 min 38 min 38 min
E, Support length in. 3.5 min 2.0 min 2.0 min
mm 90 min 50 min 50 min
F, Support width ←——————not less than G——————→
G, Support height in. 2.0 2.0 2.0 61
mm 50 50 50 625
R, Support radius in. 0.075 0.075 0.075 60.025
mm 1.0 1.0 1.0 60.1
H, Stop width in. 3.5 min 2.0 min 2.0 min 62
mm 90 min 50 min 50 min 650
I, Weld clearance in. 0.9 0.9 0.9 60.1
mm 22 22 22 63
J, Weld clearance depth in. 0.4 min 0.4 min 0.4 min
mm 10 min 10 min 10 min
FIG. 4 Anvil Dimensions
specimens (for example, mechanical test specimens) required
for evaluation of other material properties.
FIG. 5 Portable Drop-Weight Test Machine Used for Tests at
8.4 Special Conditions for Forgings and Castings—Where
Different Fabrication Sites
drop-weight testing of cast or forged material is specified, the
size and location of integrally attached pad projections or
separatelybutsimultaneouslywiththeproduct.Chillsshallnot
prolongations to be used for specimen fabrication shall be
be used. The test-material coup
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