ASTM材料与实验标准.E208_动视

ASTM材料与实验标准.E208

2025-10-03 15:07:04 责编:小OO

Designation:E208–95a(Reapproved2000)

Standard Test Method for

Conducting Drop-Weight Test to Determine Nil-Ductility Transition Temperature of Ferritic Steels1

This standard is issued under theﬁxed 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(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 in1952and 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

1.1This test method covers the determination of the nil-ductility transition(NDT)temperature of ferritic steels,5⁄8in.

(15.9mm)and thicker.

1.2This 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.

1.3The values stated in inch-pound units are to be regarded as the standard.

1.4This 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 appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.

2.Terminology

2.1Deﬁnitions:

2.1.1ferritic—the word ferritic as used hereafter refers to all a-Fe steels.This includes martensitic,pearlitic,and all other nonaustenitic steels.

2.1.2nil-ductility transition(NDT)temperature—the maxi-mum temperature where a standard drop-weight specimen breaks when tested according to the provisions of this method.

3.Summary of Test Method

3.1The drop-weight test employs simple beam specimens specially prepared to create a material crack in their tensile surfaces at an early time interval of the test.The test is conducted by subjecting each of a series(generally four to 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 load is provided by a guided,free-falling weight with an energy of250to1200ft-lbf(340to1630J)depending on the yield strength of the steel to be tested.The specimens are prevented by a stop from deﬂecting more than a few tenths of an inch.

3.2The usual test sequence is as follows:After the prepa-ration and temperature conditioning of the specimen,the initial drop-weight test is conducted at a test temperature estimated to be near the NDT temperature.Depending upon the results of theﬁrst test,tests of the other specimens are conducted at suitable temperature intervals to establish the limits within 10°F(5°C)for break and no-break performance.A duplicate test at the lowest no-break temperature of the series is conducted to conﬁrm no-break performance at this tempera-ture.

3.3In1984,the method of applying the crack-starter weld bead was changed from a two-pass technique to the current single-pass procedure,and the practice of repair-welding of the crack-starter weld bead was prohibited.For steels whose properties are inﬂuenced by tempering or are susceptible to temper embrittlement,the nil-ductility transition(NDT)tem-perature obtained using the single-pass crack-starter weld bead

1This test method is under the jurisdiction of the ASTM Committee E28on

Mechanical Testing and is the direct responsibility of Subcommittee E28.07on

Impact Testing.

Current edition approved Aug.15,1995.Published October1995.Originally

published as E208–63T.Last previous edition E208–95.

may not agree with that obtained using the previous two-pass crack-starter weld bead,or when the crack-starter bead was repaired.

4.Signiﬁcance and Use

4.1The 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.

4.2Interpretations 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 tempera-ture 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.

5.Apparatus

5.1The drop-weight machine is of simple design based on the use of readily available structural steel products.2The principal components of a drop-weight machine are a vertically guided,free-falling weight,and a rigidly supported anvil which provides for the loading of a rectangular plate specimen as a simple beam under the falling weight.Fig.2(a )illustrates a typical drop-weight machine built of standard structural shapes.

5.2A rail,or rails,rigidly held in a vertical position and in a ﬁxed relationship to the base shall be provided to guide the

weight.The weight shall be provided with suitable devices which engage the rail,or rails,and ensure that it will drop freely in a single,vertical plane.The weight may be raised by any convenient means.A weight-release mechanism,function-ing similarly to that shown in Fig.2(b ),shall be provided to release the weight quickly without affecting its free fall.The weight shall be made in one piece,or if made of several pieces,its construction shall be rigid to ensure that it acts as a unit when it strikes the specimen.The striking tup of the weight shall be a steel cylindrical surface with a radius of 1in.(25.4mm)and a minimum hardness of HRC 50throughout the

section.The weight shall be between 50and 300lb (22.7and 136kg).The rails and hoisting device shall permit raising the weight various ﬁxed distances to obtain potential energies of 250to 1200ft-lbf (340to 1630J).

5.3A horizontal base,located under the guide rails,shall be provided to hold and position precisely the several styles of anvils required for the standard specimens.The anvil guides shall position the anvil with the center-line of the deﬂection stops under the center-line of the striking tup of the weight.In general,the base will also support the guide rails,but this is not a requirement.The base shall rest on the rigid foundation.The base-foundation system shall be sufficiently rigid to allow the normal drop-weight energy (Table 1)to deﬂect a standard specimen to the stop at temperatures above the NDT.The base shall not jump or shift during the test,and shall be secured to the foundation if necessary to prevent motion.

5.4A guard screen,similar to that shown in Fig.2(c ),is recommended to stop broken specimen halves of the very brittle steels which break into two pieces with both halves being ejected forcefully from the machine.

5.5The general characteristics of two of the anvils required are illustrated in Fig.3.The anvils shall be made in accordance with the dimensions shown in Fig.4.The anvil supports and deﬂection stops shall be steel-hardened to a minimum hardness of HRC 50throughout their cross section.The space between the two stops is provided as clearance for the crack-starter weld

2Detail drawings for the construction of this machine are available from ASTM Headquarters.Order PCN

12-502080-00.

FIG.1Generalized 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

on the specimen.The deﬂection stops may be made in two separate pieces,if desired.The anvil-base system shall be sufficiently rigid to allow the normal drop-weight energy (Table 1)to deﬂect the specimen to the stop at temperatures well above the NDT.

5.6A measuring system shall be provided to assure that the weight is released from the desired height for each test,within the limits of +10,−0%.

5.7Modiﬁcations of the equipment or assembly details of the drop-weight machine shown in Fig.2are permitted provided that the modiﬁed machine is functionally equivalent.Fig.5illustrates a portable machine design used by an industrial concern for drop-weight tests of materials used for pressure vessel components at different fabrication sites.

6.Precautions

6.1The drop-weight test was devised for measuring fracture initiation characteristics of 5⁄8-in.(15.9-mm)and thicker struc-tural materials.This test is not recommended for steels less than 5⁄8-in.thick. 6.2This test method establishes standard specimens and conditions to determine the NDT temperature of a given steel.The use of standard specimens with nonstandard test condi-tions or the use of nonstandard specimens shall not be allowed for speciﬁcation purposes.

6.3This test method employs a small weld bead deposited on the specimen surface,whose sole purpose is to provide a brittle material for the initiation of a small,cleavage crack-ﬂaw in the specimen base material during the test.Anomalous behavior may be expected for materials where the heat-affected zone created by deposition of the crack-starter weld is made more fracture resistant than the unaffected plate.This condition is developed for quenched and tempered steels of high hard-ness obtained by tempering at low temperatures.The problem may be avoided by placing the crack-starter weld on these steels before conducting the quenching and tempering heat treatment.Except for other cases which may be readily rationalized in metallurgical terms (for example,it is possible to recrystallize heavily cold-worked steels in the

heat-affected

(a )Left —Complete Assembly

(b )Upper Right —Quick Release Mechanism (c )Lower Right —Guard Screen

FIG.2Drop-Weight Test

Apparatus

zone and to develop a region of improved ductility),the heat-affected zone problem is not encountered with conven-tional structural grade steels of a pearlitic microstructure or quenched and tempered steels tempered at high temperatures to develop maximum fracture toughness.

7.Test Specimens

7.1Identiﬁcation of Material —All sample material and specimens removed from a given plate,shape,forging,or casting product shall be marked to identify their particular source (heat number,slab number,etc.).A simple identiﬁcation

system shall be used which can be employed in conjunction with an itemized table to obtain all the pertinent information.7.2Orientation —The drop-weight test is insensitive to specimen orientation with respect to rolling or forging direc-tion.However,unless otherwise agreed to,all specimens speciﬁed by the purchaser shall be of the same orientation and it shall be noted in the test report.

7.3Relation to Other Specimens —Unless otherwise speci-ﬁed by the purchaser,the specimens shall be removed from the material at positions adjacent to the location of other type test

TABLE 1Standard Drop-Weight Test Conditions

Type of Specimen

Specimen Size,

in.(mm)Span,in.(mm)

Deﬂection Stop,

in.(mm)

Yield Strength Level,

ksi (MPa)Drop-Weight Energy for Given

Yield Strength Level A

ft-lbf J P-1

1by 31⁄2by 14

(25.4by by 356)

12.0(305)

0.3(7.6)

30to 50(210to 340)50to 70(340to 480)70to 90(480to 620)90to 110(620to 760)60080010001200800110013501650P-2

3⁄4by 2by 5

(19by 51by 127)

4.0(102)0.06(1.5)

30to 60(210to 410)60to 90(410to 620)90to 120(620to 830)120to 150(830to 1030)250300350400350400450550P-3

5⁄8by 2by 5

(15.9by 51by 127)

4.0(102)0.075(1.9)

30to 60(210to 410)60to 90(410to 620)90to 120(620to 830)120to 150(830to 1030)

250300350400

350400450550

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.3General Appearance of the Anvils Required for Drop-Weight NDT

Tests

specimens (for example,mechanical test specimens)required

for evaluation of other material properties.

7.4Special Conditions for Forgings and Castings —Where drop-weight testing of cast or forged material is speciﬁed,the size and location of integrally attached pad projections or prolongations to be used for specimen fabrication shall be agreed to in advance by the purchaser.If the design of the casting or forging does not allow an attached test-material coupon,the following requirements shall apply:

7.4.1Drop-weight specimens cast or forged separately to the dimensions required for testing shall be allowed only where the product dimensions are equivalent and the purchaser agrees.

7.4.2Specimens may be taken from a separately produced test-material coupon if the supplier can demonstrate that it is equivalent to the product with respect to chemical composition,soundness,and metallurgical conditions.The material shall be from the same heat and shall have been fabricated under identical conditions as the product.The specimens shall be machine-cut from locations agreed to in advance by the purchaser.

7.4.3Speciﬁcally,in the case of casting requiring X-ray quality standard,the separate test-material coupon shall be cast

separately but simultaneously with the product.Chills shall not be used.The test-material coupon shall be in proportion to the thickness,T,in the cast product,where T is diameter of the largest circle that can be inscribed in any cross section of the casting,or where T is deﬁned in advance by the purchaser as the nominal design thickness,as follows:

Thickness,T ,in.(mm)Separately Cast,Nonchilled,Test-Coupon Size 1⁄2

(12.7)and less None required

5⁄8to 2(15.9to 50.8)

When several small castings are poured from one heat,one casting shall be used to provide test specimens,if adaptable

5⁄8to 1(15.9to 25.4)

T by 2by 5in.(127mm)for irregularly shaped cast-ings

>1to 3(25.4to 76.2)>3to 5(76.2to 127)T by 4.5T by 4.5T T by 3T by 3T

Over 5(127)T by 3T by 3T for castings that are representative of cast plates

Over 5(127)

T by T by 6=T for castings that are representative of cast plates

7.4.4Specimens showing casting or metallurgical faults on broken fracture surfaces shall be

“No-Test.”

Anvil Dimension Units

Specimen Type Tolerance

P-1

P-2

P-3

S ,Span

in.mm 12.0305 4.0100 4.010060.0561.5D ,Deﬂection stop in.mm 0.307.600.0601.500.0751.9060.00260.05A ,Anvil length ←——————––not critical––——————→B ,Anvil width ←——————––not critical––——————→C ,Anvil thickness in.mm 1.5min 38min 1.5min 38min 1.5min 38min E ,Support length in.mm 3.5min 90min 2.0min 50min 2.0min 50min

F ,Support width ←——————not less than

G ——————→G ,Support height in.mm 2.050 2.050 2.05061625R ,Support radius in.mm 0.0751.00.0751.00.0751.060.02560.1

H ,Stop width in.mm 3.5min 90min 2.0min 50min 2.0min 50min 62650

I ,Weld clearance in.mm 0.9220.9220.92260.163

J ,Weld clearance depth

in.mm 0.4min 10min 0.4min 10min 0.4min 10min

FIG.4Anvil

Dimensions

FIG.5Portable Drop-Weight Test Machine Used for Tests at

Different Fabrication

Sites

7.5Size of Blank —Dimensions of the blank size required for standard test specimens are shown in Fig. 6.Equally signiﬁcant NDT temperatures,within 610°F (65°C),are determined for a given steel with tests using any of the standard specimens.As may be convenient for the particular thickness of material,any of the standard specimens shown in Fig.6and prepared as described in Section 7may be chosen for this method.The results obtained with standard test conditions shall comply with the requirements of this method for deter-mining the NDT temperature.

7.6Specimen Cutting —The specimen sample material and the specimen ends may be ﬂame-cut.The specimen sides shall be saw-cut or machined,using adequate coolant to prevent specimen overheating,and shall be a minimum of 1in.from any ﬂame-cut surface.Products thicker than the standard specimen thickness shall be machine-cut to standard thickness from one side,preserving an as-fabricated surface unless otherwise speciﬁed,or agreed to,in advance by the purchaser.The as-fabricated surface so preserved shall be the welded (tension)surface of the specimen during testing.

7.7Crack-Starter Weld —The crack-starter weld,which is a centrally located weld bead,approximately 2in.(50mm)long

(WL of Fig.6)and 1⁄2in.(12.7mm)wide,shall be deposited on the as-fabricated tension surface of the drop-weight speci-men in a single pass.3To assist the welding operator in centering the weld deposit properly on the test piece,two punch marks spaced to the appropriate WL dimension of Fig.6shall be positioned as A and D as shown in Fig.7(a).As an alternative to the punch marks,a copper template containing a centrally positioned slot,1in by WL +1⁄2in.(25mm by WL +13mm)Fig.7(b),may be used.4See Fig.7(b).The weld shall start from either Point A or D and shall proceed without interruption as a stringer bead (no weaving)to the other point.The bead appearance is determined by the amper-age,arc voltage,and speed of travel used.A current of 180to 200A,a medium arc length,and a travel speed that will result in a moderately high-crowned bead have been found to be suitable conditions.An enlarged view of an as-deposited crack-starter weld is shown in Fig.7(c ).Providing a heat sink under P-2and P-3specimens during welding is recommended but not required in order to minimize microstructural changes to these smaller specimens.

The following sources have indicated that they produce appropriate electrodes:(1)Wearshield MM Electrodes,available from Lincoln Electric Co.,22801St.Clair Ave.,Cleveland,OH 44117-1199;(2)McKay DWT 3⁄16-in.diameter,available from Teledyne McKay,P.O.Box 1509,York,PA 17405-1509;(3)OK Selectrode 830304-mm diameter,item number 8330404000,available from Esab AB,Box 8004,S-40277Goteborg,Sweden;(4)Conarcrom 3505-mm diameter,available from Conarco,Calle 18No 4079-(1672V .Lynch),Buenos Aires,Argentina.Each lot of electrodes shall be checked by the user in accordance with the requirements of 7.10for suitability with the material the user is testing.4

The copper template is especially recommended for the Type P-2and P-3specimens since it eliminates weld spatter which may interfere with proper seating of the specimen during

test.

Dimension Units Specimen Type

P-1

P-2

P-3

Dimension Tolerance Dimension Tolerance Dimension

Tolerance T ,Thickness in.mm 1.02560.1262.50.751960.0461.00.621660.0260.5L ,Length in.mm 14.036060.5610 5.013060.5610 5.013060.5610W ,Width in.mm 3.59060.162.0 2.05060.0461.0 2.05060.0461.0WL ,Weld length

in.mm

2.56

3.5

61625

1.7544.561.0625

1.7544.5

61.0625.0

N OTE 1—The length of the weld bead is not critical,provided that the crack-starter notch is at the center of specimen and that the weld bead does not contact the support ﬁxture when the specimen is fully deﬂected.

FIG.6Standard Drop-Weight Specimen

Dimensions

7.7.1Microstructure of Base Metal —Data presented show that the method of depositing the weld bead can inﬂuence the microstructure of the heat-affected zone under the weld notch which in turn can inﬂuence the NDT determined especially in heat-treated steels.5

7.8Weld Notch —The ﬁnal preparation of the specimen consists of notching the deposited weld at the center of the bead length.Care shall be taken to ensure that only the weld deposit is notched and that the cutting tools do not contact the specimen surface.The notch may be cut with thin abrasive disks,as shown in Fig.8,or other convenient cutting tools such as mechanical saws,hack saws,etc.,or electrical discharge machining.The weld-notch details and a representative ex-ample of a notched weld are given in Fig.9.

7.9Measuring Weld-Notch Depth —The depth of the notch from the crown of the weld will vary with expected variations in weld-crown dimensions.The depth of the notch is not

measured,since it is the thickness of the weld remaining above the specimen and under the bottom of the notch that has been standardized,as shown in Fig.9.This weld thickness above the specimen shall be maintained across as much of the weld width as permitted by the bead contour.Fig.10illustrates an optional device for measuring the thickness of weld metal at the bottom of the notch.The adjustable dial indicator with bridge-support is set at zero while in position on the specimen with the indicator tip contacting the specimen surface immediately adjacent to the notch.The bridge is then placed over the weld with the indicator tip resting on the bottom of the notch to measure the weld metal thickness directly.After the operator has gained experience in the preparation of a few specimens,the instrument need be used only in the ﬁnal checking of the ﬁnished notch.

7.10Other Crack-Starter Welds —The satisfactory comple-tion of drop-weight tests is dependent upon the “crack-starting”conditions developed by the notched weld.As shown sche-matically in Fig.11,the specimen deﬂection,D C ,that cracks the weld,is signiﬁcantly less than the allowable anvil stop

Tsukada,H.,Suzuki,I.I.,and Tanaka,Y .,“A Study on Drop-Weight Test Using A508Class 2Steel,”Japan Steel Works,Ltd.,December 1,

1981.

FIG.7Methods of Locating the Weld Deposit Properly on the Test

Specimen

deﬂection,D A ,for all standard thickness,T,specimens tested on the proper span,S.The carefully prepared and specially handled electrode (described in 7.73)has been proved success-ful for crack-starting purposes for all temperatures up to approximately 400°F (200°C).Other weld materials shall be considered to perform satisfactorily as crack-starters if they also develop cleavage cracks at suitably high test temperatures at or near the instant that yielding occurs in the surface ﬁbers of the test specimen.Weld materials,other than those described in 7.7,may be used for the crack-starter bead provided the following requirements are met:

7.10.1Using standard conditions as speciﬁed in Table 1,three standard Type P-2specimens (3⁄4by 2by 5in.)(19by 51by 127mm)shall be drop-weight tested at a temperature 100°F (55°C)or more above the NDT temperatures of the plate material.

7.10.2If the three tests demonstrate that the weld notch is always cracked upon deﬂection of the specimen tension surface to the maximum amount permitted by the proper anvil stop,

the

N OTE 1—The weld shown does not comply with the current procedure which speciﬁes that the weld shall start from either end and shall proceed without interruption.

FIG.8Notching of Crack-Starter Weld

Deposit

FIG.9Weld-Notch Details and Example of a Notched

Weld

FIG.10Method for Measuring Weld Metal Thickness at the

Bottom of the

Notch

FIG.11Drop-Weight Test

Method

other crack-starter weld shall be authorized and considered to conform to the requirements of this method.

7.10.3Welding procedures or crack-starter weld dimensions other than those described in 7.7shall be considered to perform satisfactorily as crack-starters if they are demonstrated to develop cleavage cracks at suitably high test temperatures at or near the instant that yielding occurs in the surface ﬁbers of the test specimens.For example,a 3⁄4to 1-in.long crack-starter weld deposited in one direction only with the welding condi-tions and the electrodes described in 7.7has been used successfully as a crack-starter weld for the Type P-3specimen.The shorter weld reduces to total heat input into the specimen and is considered less likely to cause metallurgical changes in the specimen base materials of the low-alloy,high-tensile strength pressure vessel steels.For the Type P-1specimen,the shorter weld does not provide the reproducibility or consis-tency for crack-starting purposes obtained with the standard crack-starter weld described in 7.7.Other welding procedures or crack-starter weld dimensions than those described in 7.7may be used as the crack-starter bead for a given standard type (P-1,P-2,or P-3)specimen provided that three specimens are tested in accordance with 7.10.1and results obtained in accordance with 7.10.2.

8.Procedure—General

8.1Some care and thought are necessary to make a success-ful drop-weight determination of the NDT temperature.Ad-equate auxiliary equipment and a deﬁnite procedure will aid in making the test.The following sections will deﬁne in detail and in orderly fashion the equipment and procedure requirements:8.2Conduct the test by placing a specimen in a heating or cooling device until it is at the desired temperature.Then place it with minimum loss of time (see 12.4)on the anvil and align where it will be struck squarely by the weight.Allow the weight to drop from a known preselected height on the specimen.Examine the specimen after the strike to determine its condition as deﬁned by the requirements of this method.Repeat this process until the NDT temperature has been determined.

8.3The number of specimens required to determine the NDT temperature is a function of the experience of the operator with the material and of the use of an adequate procedure.A skilled operator working with known material can determine the NDT temperature with as few as three speci-mens.Generally,six to eight specimens are required.9.Specimen—Anvil Alignment

9.1Anvil Requirements —Test each type of drop-weight specimen only on the anvil designated for that type specimen in accordance with Table 1.

9.2Specimen-Anvil Alignment —In order to obtain a valid test properly align the specimen on the anvil.Align the specimen,anvil,and weigh so the specimen is struck under the following conditions:

9.2.1The specimen shall be horizontal and the ends shall rest on the anvil supports.

9.2.2The striking tup of the weight shall strike within 60.1in.(62.5mm)of a line on the compression side of the specimen,normal to a long edge and directly opposite the notch in the crack-starter weld.

9.2.3No part of the crack-starter weld will touch the deﬂection stops at any time during the test.

9.2.4The specimen sides and ends shall be free from any interference during the test.

9.3Alignment Tool —The optional technique shown in Fig.12has been used successfully to achieve longitudinal and angular specimen alignment of the specimen.Draw a wax-pencil line on the compression surface of the specimen normal to a long edge and directly opposite the notch.Place the specimen on the anvil so this line coincides with the edge of a removable guide bar.Place the bar against the machine rails so that its edge deﬁnes the striking line of the tup on the weight.10.Selection of Test Energy

10.1Strike the specimen by a free-falling weight having adequate energy to deﬂect the specimen sufficiently to crack the weld deposit and to make the tension surface contact the anvil stop.The design of the machine permits the use

FIG.12Method for Alignment of

Specimen

various impact energies to accommodate the different strength levels of the various materials tested.The standard test conditions shown in Table 1have been developed by experi-ence and shall be used for the test series of a given steel unless “No-Test”performance is experienced.The indicated energies can be obtained by lifting the weight the required distance from the compression surface of the specimen.

10.2Proper contact of the tension surface of the specimen with the deﬂection stop shall be deﬁned as follows:Scribe a wax-pencil line on the tension surface of a standard specimen parallel to and in line with the mechanical notch cut in the crack-starter weld deposit,Fig.13(a ).Apply clean masking tape,or a similar material,to the top surface of the anvil deﬂection stop blocks,Fig.13(b ).Align the test specimen on the anvil and strike once by the weight with the standard conditions,Table 1,for the steel involved.Transfer of the wax-pencil line from specimen to the tape shall indicate that the specimen was bent sufficiently (Fig.13(c )).The above procedure,to ensure proper contact of the tension surface of the specimen with the deﬂection stop blocks,is considered a “built-in”standardization feature of the test method,and it shall be employed for each drop-weight test to preclude “No-Test”performance as described in 13.2.3and 13.3.

10.3If the weld crack and anvil stop contact criteria are not met by the Table 1energies,increase the drop-weight energy in 100-ft-lb increments for the Type P-1specimens or 50-ft-lb (68-J)increments for the Type P-2and P-3specimens until they are met.Do not use drop-weight energies above those posted on the table unless the above procedure has been followed to determine the excess energy requirements.11.Selection of Test Temperatures

11.1The selection of test temperatures is based on ﬁnding,with as few specimens as possible,a lower temperature where the specimen breaks and an upper temperature where it does not break,and then testing at intervals between these tempera-tures until the temperature limits for break and no-break performance are determined within 10°F (5°C).The NDT temperature is the highest temperature where a specimen

breaks when the test is conducted by this procedure.Test at least two specimens that show no-break performance at a temperature 10°F (5°C)above the temperature judged to be the NDT point.

11.2Conduct the initial test at a temperature estimated to be near the NDT.This temperature and all subsequent test temperatures shall be integral multiples of 10°F or 5°C.Additional tests can be conducted at temperatures based on the experience of the operator or on those suggested in Table 2.12.Measurement of Specimen Temperatures

12.1The entire test specimen shall be at a known and uniform temperature during the test.It shall be assumed that if it is fully immersed in a stirred-liquid,constant temperature bath of known temperature and separated from an adjacent specimen by a minimum of 1in.(25.4mm)all around for a period of at least 45min prior to the test,the specimen temperature shall be the same as the bath temperature.If a gas heat-transfer medium is used,increase the required minimum holding time to 60min.If it can be shown by appropriate test techniques,such as using a thermocouple buried in the center of a dummy test specimen,that specimen equilibrium tempera-tures can be developed in a shorter period,the tester can reduce the specimen-holding period provided that he has prior ap-proval of the purchaser.The constant-temperature baths or ovens may be of any type that will beat or cool the specimens to a known and uniform temperature.

12.2Measure the bath temperature by a device with cali-bration known to 62°F or 61°C.

12.3Any convenient means may be used to remove the specimen from the temperature bath and transfer it to the test machine provided it shall not affect the specimen temperature control.Tongs,if used,shall be kept in the temperature bath to maintain a temperature equivalent to the specimen tempera-ture.Rubber-gloved hands,in general,are the most convenient handling tool.The specimen shall be handled away from the fracture

area.

(a )(b )

(c )

(a )Wax Pencil Line Scribed on Tension Side of a Specimen (b )Application of Masking Tape to Anvil Stop Surfaces

(c )Transfer of Wax Lines to the Tape When the Specimen Hits the Stop

FIG.13Method Employed to Indicate Contact of the Specimen with the Anvil

Stop

12.4If more than 20s elapse in the period of removing the specimen from the bath prior to release of the weight,tem-perature control shall presume to have been lost and the specimen shall be returned to the bath.

12.5Considerable experience has been accumulated with baths of the following type,and it is described here for the convenience and option of the tester.A deep,insulated metal container holding from 1⁄2to 10gal (1.9to 38L)of a suitable heat-transfer liquid,such as alcohol,will maintain a given temperature for the required specimen-holding period with minor manual adjustments.By immersing an open basket of cracked dry ice or a high-wattage electrical heat in the bath,its temperature can be adjusted slightly or can be lowered or raised to a new constant level in a short period.For low-density heat-transfer liquids,a walnut-sized piece of dry ice added to the bath will sink and bubble vigorously and help stir it.If this type of bath is used,it should be deep enough to cover the specimens fully.It has been found by experience that standing the specimens on one end in the bath with their upper ends leaning on the vessel wall is most satisfactory.Specimens placed horizontally in the bath should be laid on a screen held at least 1⁄4in.(6.4mm)from the bottom.If multiple specimens are placed in one bath,they should be spaced a minimum of 1in.apart to ensure adequate heat-transfer liquid ﬂow around each.The most convenient method of bath temperature mea-surement is to use a bare thermocouple connected to an automatic recorder.

13.Interpretation of Test Results

13.1The success of the drop-weight test depends upon the development of a small cleavage crack in the crack-starter weld after a minute bending of the test specimen.The test evaluates the ability of the steel to withstand yield point loading in the presence of a small ﬂaw.The steel either accepts initiation of fracture readily under these test conditions and the test speci-men is broken,or initiation of fracture is resisted and the specimen bends the small,additional amount permitted by the anvil stop without complete fracturing.

13.2After completion of each drop-weight test,the speci-men shall be examined and the result of the test shall be recorded in accordance with the following criteria:

13.2.1Break —A specimen is considered broken if fractured to one or both edges of the tension surface.Complete separa-tion at the compression side of the specimen is not required for break performance.Typical examples of break performance are illustrated in Fig.14.

N OTE 1—To aid in determining whether a tightly closed crack extends across the tension surface to a corner it may be helpful to ﬁrst heat-tint or

dye the specimen and then to fracture it in two pieces by any convenient means.The amount of fracturing that initially occurred is then readily apparent.

N OTE 2—Should any crack,whether initiated at the crack-starter or not,propagate to the specimen edge on the tension face,consider the test a break-performance.

13.2.2No-Break —The specimen develops a visible crack in the crack-starter weld bead that is not propagated to either edge of the tension surface.Typical examples of no-break perfor-mance are illustrated in Fig.15.

13.2.3No-Test —The test shall be considered not valid if either weld-deposit notch is not visibly cracked after comple-tion of a test,or if the drop-weight specimen is not deﬂected fully to contact the anvil stop as evidenced by transfer of the wax-pencil lines to the masking tape on the anvil deﬂection stop.

TABLE 2Suggested Sequence of Drop-Weight Test Temperatures

Specimen Condition After Test at Temperature T n

Suggested Test Temperature

for Succeeding Test

No crack in weld notch

No-Test performance (see 13.2.3and 13.3)Weld crack extending less than 1⁄16in.(1.6mm)into specimen surface T n −60°F T n −30°C Weld crack extending 1⁄8to 1⁄4in.(3.2to 6.4mm)into specimen surface

T n −40°F T n −20°C Weld crack extending approximately 1⁄2the distance between specimen edge and toe of crack-starter weld bead T n −20°F T n −10°C Weld crack extending to within 1⁄4in.(6.4mm)of specimen edge T n −10°F T n −5°C Specimen “Breaks’’(see 13.2.1)

T n +40°F T n +20°C

Continue testing as described in 11.1and

11.2

N OTE 1—The weld shown does not comply with the current procedure which speciﬁes that the weld shall start from either end and shall proceed without interruption.

FIG.14Typical Examples of Broken Drop-Weight Specimens.

Fracture Reaches to at Least One

Edge

13.3A No-Test performance (13.2.3)may result from the use of insufficient impact energy,the use of a too-ductile weld metal for crack-starter purposes,or misalignment of the speci-men so that the weld-crown obstructs full deﬂection to the anvil stop.The No-Test sample shall be discarded and a retest,using another sample,shall be required.Retests,or tests of additional specimens,of a given steel found to develop

insufficient deﬂections with the standard test condition,Table 1,shall be conducted with higher impact energies (see 10.3).14.Report

14.1Report the following information:14.1.1Type of steel and heat treatment,

14.1.2Identiﬁcation of product tested—heat number,plate number,etc.,

14.1.3Identiﬁcation,orientation,and location of test speci-mens,

14.1.4Specimen type,test conditions and test temperatures employed,

14.1.5Result of test (break,no-break,or no-test)for each specimen,and

14.1.6Deviations,if any,from this test method.

15.Use of Test for Material-Qualiﬁcation Testing

15.1Speciﬁcation tests conducted at a given test tempera-ture,on a go,no-go basis,shall require that a minimum of two drop-weight specimens be tested.All specimens thus tested shall exhibit no-break performance to ensure that the NDT temperature of the steel under test is below the speciﬁcation test temperature.The breaking of one (or more)specimens at the test temperature shall indicate the NDT temperature of the material to be at or above the speciﬁcation test temperature.16.Precision and Bias

16.1Precision —The precision of this test method is being established.

16.2Bias —There is no basis for determining the bias of this test

method.

FIG.15Typical Examples of No-Break Performance in Drop-Weight Specimens.Fracture Does Not Reach

Edge

ADDITIONAL REFERENCES

Selected References Relating to Development of Drop-Weight

Test:

(1)Pellini,W.S.,“Notch Ductility of Weld Metal,”Welding Journal,Am.

Welding Soc.,V ol35,May,1956,p.217-s.

(2)Pellini,W.S.,Brandt,F.A.,and Layne,E.E.,“Performance to Cast

and Rolled Steels in Relation to the Problem of Brittle Fracture,”

Transactions,Am.Foundryman’s Soc.,V ol61,1953,p.243.

(3)Pellini,W.S.,and Srawley,J.E.,“I.Evaluating Fracture Toughness in

Pressure Vessels for Space,Aerospace,and Hydrospace—A Sympo-sium,”Journal of Metals,March,1961,pp.195–198.

(4)Puzak,P.P.,and Babecki,A.J.,“Normalization Procedures for NRL

Drop-Weight Test,”Welding Journal,Am.Welding Soc.,V ol38,May, 1959,p.209-s.

(5)Puzak,P.P.,and Pellini,W.S.,“Evaluation of the Signiﬁcance of

Charpy Tests for Quenched and Tempered Steels,”Welding Journal, Am.Welding Soc.,V ol35,No.6,1956,p.275-s.

(6)Puzak,P.P.,Schuster,M.E.,and Pellini,W.S.,“Applicability of

Charpy Test Data,”Welding Journal,Am.Welding Soc.,V ol33, September,1954,p.443-s.

(7)Puzak,P.P.,Schuster,M.E.,and Pellini,W.S.,“Crack Starter Tests of

Ship Fracture and Project Steels,”Appendix entitled,“Procedures for NRL Drop Weight Test,”Welding Journal,Am.Welding Soc.,V ol33, No.10,October,1954,p.481-s.

Selected References Relating to Correlation of NDT to

Service Failures:

(8)Babecki,A.J.,Puzak,P.P.,and Pellini,W.S.,“Report of Anomalous

8Brittle’Failures of Heavy Steel Forgings at Elevated Temperatures,”

Paper No.59-MET-6,Am.Soc.Mechanical Engrs.,May,1959.(9)Lange,E.A.,and Klier,E.P.,“A Study of Fracture Development and

Materials Properties in PVRC Vessels1and2,”Welding Journal,Am.

Welding Soc.,V ol41,February,1962,p.53-s.

(10)Pellini,W.S.,Steele,L.E.,and Hawthorne,J.R.,“Analysis of

Engineering and Basic Research Aspects of Neutron Embrittlement of Steels,”NRL Report5780,April17,1962;also Welding Journal, Am.Welding Soc.,October,1962.

(11)Puzak,P.P.,Babecki,A.J.,and Pellini,W.S.,“Correlations of Brittle

Fracture Service Failures with Laboratory Notch-Ductility Tests,”

Welding Journal,Am.Welding Soc.,V ol37,No.9,September,1958, p.391-s.

Selected References Relating to Neutron Irradiation

Embrittlement:

(12)Hawthorne,J.R.,and Steele,L.E.,“Effect of Neutron Irradiation on

Charpy-V Drop Weight Test Transition Temperatures of Various Steels and Weld Metals.”ASTM STP286,Am.Soc.Testing Mats., 1960,pp.33–56.

(13)Hawthorne,J.R.,Steele,L. E.,and Pellini,W.S.,“Effects of

Properties of Reactor Structural Materials,”Paper No.61-WA-332, Am.Soc.Mechanical Engrs.,October1961.

(14)Steele,L.E.,and Hawthorne,J.R.,“Effect of Irradiation Temperature

on Neutron-Induced Changes in Notch Ductility of Pressure-Vessel Steels,”NRL Report5629,June28,1961.

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