ASTM E208-95a(2000)
(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.
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:E208–95a(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.
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. Summary of Test Method
1.1 This test method covers the determination of the nil- 3.1 The drop-weight test employs simple beam specimens
ductility transition (NDT) temperature of ferritic steels, ⁄8 in. specially prepared to create a material crack in their tensile
(15.9 mm) and thicker. surfaces at an early time interval of the test. The test is
1.2 This test method may be used whenever the inquiry, conducted by subjecting each of a series (generally four to
contract,order,orspecificationstatesthatthesteelsaresubject eight) of specimens of a given material to a single impact load
to fracture toughness requirements as determined by the at a sequence of selected temperatures to determine the
drop-weight test. maximumtemperatureatwhichaspecimenbreaks.Theimpact
1.3 Thevaluesstatedininch-poundunitsaretoberegarded loadisprovidedbyaguided,free-fallingweightwithanenergy
as the standard. of 250 to 1200 ft-lbf (340 to 1630 J) depending on the yield
1.4 This standard does not purport to address all of the strength of the steel to be tested. The specimens are prevented
safety concerns, if any, associated with its use. It is the by a stop from deflecting more than a few tenths of an inch.
responsibility of the user of this standard to establish appro- 3.2 The usual test sequence is as follows: After the prepa-
priate safety and health practices and determine the applica- rationandtemperatureconditioningofthespecimen,theinitial
bility of regulatory limitations prior to use. drop-weighttestisconductedatatesttemperatureestimatedto
be near the NDT temperature. Depending upon the results of
2. Terminology
the first test, tests of the other specimens are conducted at
2.1 Definitions: suitable temperature intervals to establish the limits within
2.1.1 ferritic—the word ferritic as used hereafter refers to 10°F (5°C) for break and no-break performance. A duplicate
all a-Fe steels. This includes martensitic, pearlitic, and all
test at the lowest no-break temperature of the series is
other nonaustenitic steels. conducted to confirm no-break performance at this tempera-
2.1.2 nil-ductility transition (NDT) temperature—themaxi-
ture.
mum temperature where a standard drop-weight specimen 3.3 In 1984, the method of applying the crack-starter weld
breaks when tested according to the provisions of this method.
bead was changed from a two-pass technique to the current
single-passprocedure,andthepracticeofrepair-weldingofthe
crack-starter weld bead was prohibited. For steels whose
This test method is under the jurisdiction of the ASTM Committee E28 on
properties are influenced by tempering or are susceptible to
Mechanical Testing and is the direct responsibility of Subcommittee E28.07 on
temper embrittlement, the nil-ductility transition (NDT) tem-
Impact Testing.
Current edition approved Aug. 15, 1995. Published October 1995. Originally peratureobtainedusingthesingle-passcrack-starterweldbead
published as E208–63T. Last previous edition E208–95.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
E208–95a (2000)
may not agree with that obtained using the previous two-pass weight. The weight shall be provided with suitable devices
crack-starter weld bead, or when the crack-starter bead was which engage the rail, or rails, and ensure that it will drop
repaired. freely in a single, vertical plane. The weight may be raised by
any convenient means.Aweight-release mechanism, function-
4. Significance and Use
ing similarly to that shown in Fig. 2( b), shall be provided to
4.1 Thefracture-strengthtransitionsofferriticsteelsusedin
release the weight quickly without affecting its free fall. The
the notched condition are markedly affected by temperature. weightshallbemadeinonepiece,orifmadeofseveralpieces,
For a given “low” temperature, the size and acuity of the flaw
its construction shall be rigid to ensure that it acts as a unit
(notch) determines the stress level required for initiation of when it strikes the specimen. The striking tup of the weight
brittlefracture.Thesignificanceofthistestmethodisrelatedto
shall be a steel cylindrical surface with a radius of 1 in. (25.4
establishing that temperature, defined herein as the NDT mm) and a minimum hardness of HRC 50 throughout the
temperature, at which the “small flaw” initiation curve, 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 Temperature
falls to nominal yield strength stress levels with decreasing section. The weight shall be between 50 and 300 lb (22.7 and
temperature, that is, the point marked NDT in Fig. 1. 136 kg). The rails and hoisting device shall permit raising the
4.2 Interpretations to other conditions required for fracture weight various fixed distances to obtain potential energies of
initiation may be made by the use of the generalized flaw-size, 250 to 1200 ft-lbf (340 to 1630 J).
stress-temperature diagram shown in Fig. 1. The diagram was 5.3 Ahorizontalbase,locatedundertheguiderails,shallbe
derived from a wide variety of tests, both fracture-initiation
provided to hold and position precisely the several styles of
and fracture-arrest tests, as correlated with the NDT tempera- anvils required for the standard specimens. The anvil guides
tureestablishedbythedrop-weighttest.ValidationoftheNDT
shall position the anvil with the center-line of the deflection
concept has been documented by correlations with numerous stops under the center-line of the striking tup of the weight. In
servicefailuresencounteredinship,pressurevessel,machinery
general,thebasewillalsosupporttheguiderails,butthisisnot
component, forged, and cast steel applications.
a requirement. The base shall rest on the rigid foundation. The
base-foundation system shall be sufficiently rigid to allow the
5. Apparatus
normal drop-weight energy (Table 1) to deflect a standard
5.1 The drop-weight machine is of simple design based on
specimen to the stop at temperatures above the NDT.The base
the use of readily available structural steel products. The
shall not jump or shift during the test, and shall be secured to
principalcomponentsofadrop-weightmachineareavertically
the foundation if necessary to prevent motion.
guided,free-fallingweight,andarigidlysupportedanvilwhich
5.4 A guard screen, similar to that shown in Fig. 2(c), is
provides for the loading of a rectangular plate specimen as a
recommended to stop broken specimen halves of the very
simple beam under the falling weight. Fig. 2(a) illustrates a
brittle steels which break into two pieces with both halves
typical drop-weight machine built of standard structural
being ejected forcefully from the machine.
shapes.
5.5 The general characteristics of two of the anvils required
5.2 Arail, or rails, rigidly held in a vertical position and in
areillustratedinFig.3.Theanvilsshallbemadeinaccordance
a fixed relationship to the base shall be provided to guide the
with the dimensions shown in Fig. 4. The anvil supports and
deflectionstopsshallbesteel-hardenedtoaminimumhardness
of HRC 50 throughout their cross section. The space between
Detail drawings for the construction of this machine are available fromASTM
Headquarters. Order PCN 12-502080-00. thetwostopsisprovidedasclearanceforthecrack-starterweld
E208–95a (2000)
(a) Left—Complete Assembly
(b) Upper Right—Quick Release Mechanism
(c) Lower Right—Guard Screen
FIG. 2 Drop-Weight Test Apparatus
on the specimen. The deflection stops may be made in two 6.2 This test method establishes standard specimens and
separate pieces, if desired. The anvil-base system shall be conditions to determine the NDT temperature of a given steel.
sufficiently rigid to allow the normal drop-weight energy The use of standard specimens with nonstandard test condi-
(Table 1) to deflect the specimen to the stop at temperatures
tions or the use of nonstandard specimens shall not be allowed
well above the NDT.
for specification purposes.
5.6 Ameasuring system shall be provided to assure that the
6.3 This test method employs a small weld bead deposited
weight is released from the desired height for each test, within
on the specimen surface, whose sole purpose is to provide a
the limits of+10, −0%.
brittlematerialfortheinitiationofasmall,cleavagecrack-flaw
5.7 Modifications of the equipment or assembly details of
in the specimen base material during the test. Anomalous
the drop-weight machine shown in Fig. 2 are permitted
behaviormaybeexpectedformaterialswheretheheat-affected
provided that the modified machine is functionally equivalent.
zone created by deposition of the crack-starter weld is made
Fig. 5 illustrates a portable machine design used by an
morefractureresistantthantheunaffectedplate.Thiscondition
industrial concern for drop-weight tests of materials used for
is developed for quenched and tempered steels of high hard-
pressure vessel components at different fabrication sites.
ness obtained by tempering at low temperatures. The problem
6. Precautions
may be avoided by placing the crack-starter weld on these
steels before conducting the quenching and tempering heat
6.1 Thedrop-weighttestwasdevisedformeasuringfracture
initiation characteristics of ⁄8-in. (15.9-mm) and thicker struc- treatment. Except for other cases which may be readily
rationalized in metallurgical terms (for example, it is possible
tural materials. This test is not recommended for steels less
than ⁄8-in. thick. to recrystallize heavily cold-worked steels in the heat-affected
E208–95a (2000)
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.
FIG. 3 General Appearance of the Anvils Required for Drop-Weight NDT Tests
zone and to develop a region of improved ductility), the system shall be used which can be employed in conjunction
heat-affected zone problem is not encountered with conven- with an itemized table to obtain all the pertinent information.
tional structural grade steels of a pearlitic microstructure or
7.2 Orientation—The drop-weight test is insensitive to
quenchedandtemperedsteelstemperedathightemperaturesto
specimen orientation with respect to rolling or forging direc-
develop maximum fracture toughness.
tion. However, unless otherwise agreed to, all specimens
specified by the purchaser shall be of the same orientation and
7. Test Specimens
it shall be noted in the test report.
7.1 Identification of Material—All sample material and
7.3 Relation to Other Specimens—Unless otherwise speci-
specimens removed from a given plate, shape, forging, or
fiedbythepurchaser,thespecimensshallberemovedfromthe
casting product shall be marked to identify their particular
material at positions adjacent to the location of other type test
source(heatnumber,slabnumber,etc.).Asimpleidentification
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
7.4 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 coupon shall be in proportion to the
agreed to in advance by the purchaser. If the design of the
thickness, T, in the cast product, where T is diameter of the
casting or forging doe
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