ASTM E208-06(2012)
(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
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
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 concept has been documented by correlations with numerous service failures encountered in ship, pressure vessel, machinery component, forged, and cast steel applications.
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.
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 and health practices and determine the applicability of regulatory limitations prior to use.
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Designation: E208 − 06 (Reapproved 2012)
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 (´) 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.
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
wouldhaveacommonmeaning.ThistestmethodwasoriginallypublishedasDepartmentoftheNavy
document NAVSHIPS-250-634-3.
1. Scope* 3.1.1 ferritic—thewordferriticasusedhereafterreferstoall
α-Fe steels. This includes martensitic, pearlitic, and all other
1.1 This test method covers the determination of the nil-
nonaustenitic steels.
ductility transition (NDT) temperature of ferritic steels, ⁄8 in.
(15.9 mm) and thicker.
3.1.2 nil-ductility transition (NDT) temperature—the maxi-
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.
1.3 The values stated in inch-pound units are to be regarded 4.1 The drop-weight test employs simple beam specimens
as the standard. specially prepared to create a material crack in their tensile
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
2.1 ASTM Adjuncts: strength of the steel to be tested. The specimens are prevented
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
3.1 Definitions:
drop-weighttestisconductedatatesttemperatureestimatedto
be near the NDT temperature. Depending upon the results of
This test method is under the jurisdiction of the ASTM Committee E28 on
the first test, tests of the other specimens are conducted at
Mechanical Testing and is the direct responsibility of Subcommittee E28.07 on
suitable temperature intervals to establish the limits within
Impact Testing.
Current edition approved Nov. 1, 2012. Published December 2012. Originally
10°F (5°C) for break and no-break performance. A duplicate
approved in 1963. Last previous edition approved in 2006 as E208–06. DOI:
test at the lowest no-break temperature of the series is
10.1520/E0208-06R12.
2 conducted to confirm no-break performance at this tempera-
Detail drawings for the construction of this machine are available fromASTM
Headquarters. Order ADJE0208. Original adjunct produced in 2002. ture.
*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
E208 − 06 (2012)
4.3 In 1984, the method of applying the crack-starter weld simple beam under the falling weight. Fig. 2(a) illustrates a
bead was changed from a two-pass technique to the current typical drop-weight machine built of standard structural
single-passprocedure,andthepracticeofrepair-weldingofthe shapes.
crack-starter weld bead was prohibited. For steels whose
6.2 Arail, or rails, rigidly held in a vertical position and in
properties are influenced by tempering or are susceptible to
a fixed relationship to the base shall be provided to guide the
temper embrittlement, the nil-ductility transition (NDT) tem-
weight. The weight shall be provided with suitable devices
perature obtained using the single-pass crack-starter weld bead
which engage the rail, or rails, and ensure that it will drop
may not agree with that obtained using the previous two-pass
freely in a single, vertical plane. The weight may be raised by
crack-starter weld bead, or when the crack-starter bead was
any convenient means.Aweight-release mechanism, function-
repaired.
ing similarly to that shown in Fig. 2(b), shall be provided to
release the weight quickly without affecting its free fall. The
5. Significance and Use
weightshallbemadeinonepiece,orifmadeofseveralpieces,
5.1 Thefracture-strengthtransitionsofferriticsteelsusedin
its construction shall be rigid to ensure that it acts as a unit
the notched condition are markedly affected by temperature.
when it strikes the specimen. The striking tup of the weight
For a given “low” temperature, the size and acuity of the flaw
shall be a steel cylindrical surface with a radius of 1 in. (25.4
(notch) determines the stress level required for initiation of
mm) and a minimum hardness of HRC 50 throughout the
brittlefracture.Thesignificanceofthistestmethodisrelatedto
section. The weight shall be between 50 and 300 lb (22.7 and
establishing that temperature, defined herein as the NDT
136 kg). The rails and hoisting device shall permit raising the
temperature, at which the “small flaw” initiation curve, Fig. 1,
weight various fixed distances to obtain potential energies of
falls to nominal yield strength stress levels with decreasing
250 to 1200 ft-lbf (340 to 1630 J).
temperature, that is, the point marked NDT in Fig. 1.
6.3 Ahorizontal base, located under the guide rails, shall be
5.2 Interpretations to other conditions required for fracture
provided to hold and position precisely the several styles of
initiation may be made by the use of the generalized flaw-size,
anvils required for the standard specimens. The anvil guides
stress-temperature diagram shown in Fig. 1. The diagram was
shall position the anvil with the center-line of the deflection
derived from a wide variety of tests, both fracture-initiation
stops under the center-line of the striking tup of the weight. In
and fracture-arrest tests, as correlated with the NDT tempera-
general,thebasewillalsosupporttheguiderails,butthisisnot
tureestablishedbythedrop-weighttest.ValidationoftheNDT
a requirement. The base shall rest on the rigid foundation. The
concept has been documented by correlations with numerous
base-foundation system shall be sufficiently rigid to allow the
servicefailuresencounteredinship,pressurevessel,machinery
normal drop-weight energy (Table 1) to deflect a standard
component, forged, and cast steel applications.
specimen to the stop at temperatures above the NDT.The base
shall not jump or shift during the test, and shall be secured to
6. Apparatus
the foundation if necessary to prevent motion.
6.1 The drop-weight machine is of simple design based on
the use of readily available structural steel products. The 6.4 A guard screen, similar to that shown in Fig. 2(c), is
principalcomponentsofadrop-weightmachineareavertically recommended to stop broken specimen halves of the very
guided,free-fallingweight,andarigidlysupportedanvilwhich brittle steels which break into two pieces with both halves
provides for the loading of a rectangular plate specimen as a being ejected forcefully from the machine.
FIG. 1 Generalized Fracture Analysis Diagram Indicating the Approximate Range of Flaw Sizes Required for Fracture Initiation at Vari-
3, 4
ous Levels of Nominal Stress, as Referenced by the NDT Temperature
E208 − 06 (2012)
(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
Specimen Size, Deflection Stop, Yield Strength Level, A
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.
E208 − 06 (2012)
6.5 The general characteristics of two of the anvils required tions or the use of nonstandard specimens shall not be allowed
areillustratedinFig.3.Theanvilsshallbemadeinaccordance for specification purposes.
with the dimensions shown in Fig. 4. The anvil supports and
7.3 This test method employs a small weld bead deposited
deflectionstopsshallbesteel-hardenedtoaminimumhardness
on the specimen surface, whose sole purpose is to provide a
of HRC 50 throughout their cross section. The space between
brittlematerialfortheinitiationofasmall,cleavagecrack-flaw
thetwostopsisprovidedasclearanceforthecrack-starterweld
in the specimen base material during the test. Anomalous
on the specimen. The deflection stops may be made in two
behaviormaybeexpectedformaterialswheretheheat-affected
separate pieces, if desired. The anvil-base system shall be
zone created by deposition of the crack-starter weld is made
sufficiently rigid to allow the normal drop-weight energy
morefractureresistantthantheunaffectedplate.Thiscondition
(Table 1) to deflect the specimen to the stop at temperatures
is developed for quenched and tempered steels of high hard-
well above the NDT.
ness obtained by tempering at low temperatures. The problem
6.6 Ameasuring system shall be provided to assure that the
may be avoided by placing the crack-starter weld on these
weight is released from the desired height for each test, within
steels before conducting the quenching and tempering heat
the limits of+10, −0%.
treatment. Except for other cases which may be readily
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
initiation characteristics of ⁄8-in. (15.9-mm) and thicker struc-
8.1 Identification of Material—All sample material and
tural materials. This test is not recommended for steels less
specimens removed from a given plate, shape, forging, or
than ⁄8-in. thick.
casting product shall be marked to identify their particular
7.2 This test method establishes standard specimens and
source(heatnumber,slabnumber,etc.).Asimpleidentification
conditions to determine the NDT temperature of a given steel. system shall be used which can be employed in conjunction
The use of standard specimens with nonstandard test condi- with an itemized table to obtain all the pertinent information.
FIG. 3 General Appearance of the Anvils Required for Drop-Weight NDT Tests
E208 − 06 (2012)
Specimen Type
Anvil Dimension Units Tolerance
P-1 P-2 P-3
S, Span in. 12.0 4.0 4.0 ±0.05
mm 305 100 100 ±1.5
D, Deflection stop in. 0.30 0.060 0.075 ±0.002
mm 7.60 1.50 1.90 ±0.05
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 ±1
mm 50 50 50 ±25
R, Support radius in. 0.075 0.075 0.075 ±0.025
mm 1.0 1.0 1.0 ±0.1
H, Stop width in. 3.5 min 2.0 min 2.0 min ±2
mm 90 min 50 min 50 min ±50
I, Weld clearance in. 0.9 0.9 0.9 ±0.1
mm 22 22 22 ±3
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
8.2 Orientation—The drop-weight test is insensitive to 8.4.1 Drop-weight specimens cast or forged separately to
specimen orientation with respect to rolling or forging direc- thedimensionsrequiredfortestingshallbeallowedonlywhere
tion. However, unless otherwise agreed to, all specimens
the product dimensions are equivalent and the purchaser
specified by the purchaser shall be of the same orientation and agrees.
it shall be noted in the test report.
8.4.2 Specimens may be taken from a separately produced
test-material coupon if the supplier can demonstrate that it is
8.3 Relation to Other Specimens—Unless otherwise speci-
fiedbythepurchaser,thespecimensshallberemovedfromthe equivalenttotheproductwithrespecttochemicalcomposition,
material at positions adjacent to the location of other type test
soundness, and metallurgical
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