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है”ह”ह

IS 10623 (1983): Drop Weight Tear Test on Ferritic Steelsand Line Pipe [MTD 3: Mechanical Testing of Metals]

DROP WEIGHT TEAR TEST ON

IS : 10623 - 1983

Indian Standard

FERRITIC STEELS AND LINE PIPE

Methods of Physical Tests Sectional Committee, SMDC 3

Chairman Representing

SHRI P. K. CHAKRAVARTY The Tata Iron & Steel Co Ltd,Jamshedpur

Members

SBRI R. K. ABKOL Bharat Steel Tubes Ltd, Ganaur SHRI KANWALJIT SINUH ARORA ( Alternate )

SHRI SUJIT KUMAR BASU M. N. Dastur & Co (P) Ltd, Calcutta SHRI S. SW GUPTA ( Alternate )

DR A. CHAKRABORTY Usha Martin Black (Wire Ropes ) Ltd, Calcutta SHRI H. MAHESWARY ( Alternate )

SHRI K. K. CRERIAN Indian Aluminium Co Ltd, Calcutta SHRI PANEAJ DE ( Alternate )

SHRI 0. P. CH~~H Associated Instrument Manufacturers’ ( India ) Private Ltd, New Delhi

SERI V. N. NANDA ( Alternate ) Da R. P. DAMBAL Indian Telephone Industries Ltd, Bangalore

SRRI N. NA~ARAJ ( Alternate ) SHRI M. K. DAS GUPTA National Physical Laboratory ( CSIR ), New Delhi DEPUTY DIRECTOR ( MET-~ ), Ministry of Railways

RDSO, LOCKNOW ASSISTANT RES. OFFICER

( MET-P ), RDSO, LUCKNOW ( Alternate ) &RI D. DUTTA The Indian Tube Co Ltd, Jamshedpur

SHRI C. B. LUNAWAT ( Alternate ) SHRI J. C. ERRY Steel Authority of India Ltd ( Bokaro Steel Plant ) SHRI K. G. GARG Directorate General of Technical Development

and Production ( Air ), New Delhi SERI P. RAGHOTHA~A RAO ( A&ernare )

SHRI A. GHOSH National Test House, Calcutta SERI D. S. MAJUMDAR ( Alternate)

SHRI S. A. HAQUE Tata Iron and Steel Co Ltd, Jamshedpur SHRI A. S. Wa~ra ( Alternate )

SHRI S. B. IDNANI Blue Star Limited, Bombay &RI G. S. SOBTI ( Alternate )

SHRI S. V. KULKARNI Fuel Instruments & Engineers Pvt Ltd, Ichalkaranji SHRI J. V. KULKARNI ( Alternate )

( Continued on page 2 )

@ CopVright 1983 INDIAN STANDARDS INSTITUTION

This publication is protected under the Indian Copyright Act ( XIV of 1957 ) and reproduction in whole or in part by any means except with written permissioa of th6 publisher shall be deemed to be an infringement of copyright under the said Act.

IS:10623- 1983

( Continued from puge 1 )

Members

SERI S. KUbrAR

Representing

Mining & Allied Machinery Corporation Ltd, Durgapur

SHRI K. S. LAKSHMINARAYAN Avery India Ltd, Calcutta SERI R. D. SEARI~A ( Alternate )

SHRI S. R. M~ZUXD~R Ministry of Defence ( DGI ) SHRI A. K. CRAKROBORTY ( Alternate )

SERI R. A. PADMANABRAN Central Mechanical Engineering Research Institute ( CSIR ), Durgapur

SHRI M. PRASAD Steel Authority of India Ltd, Ranchi SHRI N. GOPALAKRISRNA ( Alternate )

SIie,I S. RADHAKRISHNAN National Aeronautical Laboratory ( CSIR ), Bangalore

DR V. SRINIVAS~N ( Alternate ) SERI R. N. SAHA Directorate General of Supplies and Disposals,

New Delhi SHRI S. K. PANDEY ( Alternate )

SHRI D. N. SARKAR Ministry of Defence ( DGOF ) SHRI A. R. BASU ( Alternate ) .

SRRI F. C. SHARMA Directorate General of Civil Aviation, New Delhi SERI K. SWAMIAPPAN Ministry of Defence ( R & D ) SHRI H. K. TANEJA Indian Register of Shipping, Bombay

SHRI V. N. PANDEY ( Alternate ) DR V. RAO National Metallurgical Laboratory ( CSIR ),

Jamshedpur DR D. J. CEAKRAVARTI ( Alternate )

SHRI K. RAOHAVENDRAN, Director General, IS1 ( Ex-oc_oBicio Member ) Director ( Strut & Met )

Secretary

SHRI S. K. GUPTA Deputy Director ( Metals ), IS1

2

IS:10623-1983

Indian Standard

DROP WEIGHT TEAR TEST ON FERRITIC STEELS AND LINE PIPE

0. FOREWORD

0.1 This Indian Standard was adopted by the Indian Standards Institution on 27 July 1983, after the draft finalized by the Methods of Physical Tests Sectional Committee had been approved by the Structural and Metals Division Council.

0.2 This standard provides a method of test which may be used when- ever the enquiry, contract, order, or specification states that the steels are subject to fracture toughness requirements as determined by drop weight tear test. This test may also be used for the following purposes.

0.2.1 In research and development work, to study the role of metal- lurgical variables such as composition or heat treatment, or of fabrrcat- ing operations such as welding or forming on the mode of fracture propagation.

0.2.2 In evaluation of materials for service, to indicate the suitability of a material for a specific application by indicating fracture propagation behaviours at the service temperature.

0.2.3 For information or specification purposes, to provide a quality control criteria, when suitable correlations have been established with service behaviour.

0.3 In the preparation of this standard, assistance has been derived from the following:

ANSI/ASTM E 436-74 Standard method for drop-weight tear tests of ferritic steels. American Society for Testing and Materials.

ANSI/ASTM E 208-69 Standard method for conducting drop- weight test to determine nil-ductility transition temperature of ferritic steels. American Society for Testing and Materials.

API-RP 5L3 Recommended practice for conducing drop-weight tear tests on line pipe. American Petroleum Institute.

3

IS : 10623 - 1983

1. SCOPE

1.1 This standard prescribes a method for drop-weight tear test ( DWTT ) on ferritic steels and line pipe 500 mm OD and larger, with thickness between 3.2 mm to 40.0 mm in order to evaluate the nil-ductility transi- tion ( NDT ) temperature.

1.2 This test method is also suitable to determine the appearance of propagating fractures in plain carbon or low alloy steels pipes ( yield strength up to 825 N/mm2 ) over the temperature range, where the fracture mode changes from brittle to ductile.

1.3 This test method is related to establishing 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.

1.3.1 Interpretation to other conditions required for fracture, initiation may be made by the use of the generalised flaw size, stress temperature diagram as shown in Fig. 1.

TENSILE STRENGTH

YIELD POINT

tvs

*YS

iYS

INITIATION CURVES

FLAW SIZES 1

FIG. .l GENERALIZED FRACTURE ANALYSIS DIAGRAM INDICATING THE APPROXIMATE RANGE OF FLAW SIZES REQUIRED FOR FRACTURE INITCATION AT VARIOUS LEVELS OF NOM:NAL STRESS AS REFERRED

BY THE NDT TEMPERATURE

2. TESTING EQUIPMENT

2.1 Testing machine may be either a pendulum type or falling weight type, capable of giving sufficient energy to completely fracture a specimen in one impact.

4

IS:10623 -1983

2.2 The specimen shall be supported in a suitable manner to prevent sidewise rotation of the specimen during impact when tested with a falling weight.

2.3 The velocity of the hammer should not be less than 4.88 m/s.

2.4 As a guide in the design of the equipment, up to 2 712 Joules of energy may be required to fracture completely, specimens of steel, up to 12.7 mm in thickness with a tensile strength 690 N/mm2.

3. TEST SPECIMEN

3.1 The test specimen shall be 76.0 mm x 300 mm by full thickness edge notch. Figure 2 presents the dimensions and tolerances of the specimen. The specimen shall be removed from the material under test by sawing, shearing or flame cutting, with or without machining.

3.1.1 If the specimen is flame-cut it is usually difficult to press in the notch unless the heat affected zone is removed by machining.

3.1.2 The specimen shall be removed from the pipe in such a way that the length of the specimen is in the circumferential direction of the pipe.

3.1.2.1 The specimen may either be flattened completely for testing purposes or the centre 25 to 50 mm may be left with the original pipe curvature ( non-flattened specimens ). For expanded pipe with D/t range less than 40, flattening has been observed to decrease the percent shear of the fracture. Also, in non-expanded pipe the flattening has been observed to decrease the percent shear of the fracture. In case of a difference between the results of flattened and non-flattened specimens, the result from non-flattened specimen shall govern.

3.2 The notch shall be pressed to the’depth shown in Fig. 2 with a sharp ( no radius ) tool steel chisel with an included angle of 45 f 2”. Machined notches are prohibited. When many specimens are to be tested, it is helpful to use a jig which will guide the chisel and stop it at the proper depth.

3.3 The specimen shall be of full thickness - up to 19.0 mm plate/pipe Gall thickness. Specimen from plate/pipe thicker than 19.0 mm shall be either of full wall thickness, or reduced in thickness to 19’0 mm ( minimum) by machining one or both surfaces. Specimens that are reduced to a thickness less than the original thickness shall be broken at

5

G; . .

NOTCH DEPTH Smm+(Mmm

1.

RADIUS 2Smm $ bmm

_ SECTION-AA.

QAnllJS lQmmt6mm

\I/

I 0

LENc3TH 300mm f l9mm m

, I

L SPAN 250mm-+l-5mn 4 Fro. 2 DROP WEIGHT TEAR TEST SPECIMEN AND SUPPORT DIMENSION

IS : 10623 - 1983

a temperature that is reduced from the specified test temperature by the amount shown below:

@ecijed Pipe Test Temperature Thickness Reduction

mm

19-22

Above 22-30

Above 30

4. PROCEDURE

‘C

6

1 l

17

4.1 In the temperature range, - 73 to lOO’C, the procedure described in 4.1.1 and 4.1.2 shall be employed.

4.1.1 The specimen shall be completely immersed in a bath of a suitable liquid at a temperature within ZL 1°C of the prescribed test temperature for a minimum of 15 minutes prior to testing. The specimens shall be separated from each other by a distance at least equal to the thickness of the specimen, and provisions for circulation of the bath to assure uniform bath temperature, shall be made.

4.1.2 Specimen then may be removed from the bath and broken within a time period of 10 seconds. If the specimen is held out of the bath for longer than 10 seconds, it shall be reimmersed in the bath for a period of minimum of 10 minutes. The spacimen shall not be handled in the vicinity of the notch by devices, the temperature of which is appreciably different from the test temperature.

4.2 For temperature outside of the range specified in 4.1, the specimen temperature at the time of impact, within &l”C of the desired test temperature shall be maintained.

4.3 The specimen may be inserted in the testing machine SO that the notch in the specimen lines up with the centre line of the tup on the hammer within 1.60 mm. Also, the notch in the specimen shall be centred between the supports on the anvil.

4.4 The tests shall be considered invalid if the specimen buckles during the impact.

5. INTERPRETATION

5.1 Shear fracture surfaces have a dull gray silky appearance and are commonly inclined at an angle to the specimen surface. Cleavage or brittle fractures are bright and crystalline in appearance. This cleavage fracture generally extend from the root of the notch and are surrounded by a region of shear or shear lips on the specimen surface.

7

IS : 10623 - 1983

5.2 Evaluate the specimens by determining the percent shear area of the fracture surface neglecting the fracture surface for a distance of one specimen thickness, from the root of the notch and the fracture surface for a distance of one specimen thickness from the edge struck by the hammer. Figure 3 illustrates in the hatched area portion of thefr acture surface to be considered in the evaluation of the percent shear area of the fracture surface.

t =19mm FOR SPECIMENS WI’w THICKNESS GREATER THAN 19mm

/NOTCH kS AREA TO BE EVALUATED IN THE DETERMINATION OF THE PERCENTSHEAR OF THE FRACTURE SHEAR

FIG. 3 FRACTURE SURFACE INCLUDED INSHEAR AREADETERMINATION

5.3 Occasionally specimens exhibiting the fracture appearance shown in Fig. 4 may be encountered. On specimen of this type, the fracture appears to have stopped and started a number of times exhibiting inter- mittent regions of shear and cleavage in the midthickness portion of the specimen. The shear area included in the rating of the specimens of this type shall be as that shown in the hatched area of Fig. 4. The shear area in the region of intermittent shear and cleavage fracture shall be neglected in rating the specimen.

Ii IN RATING INCLUDE ONLY THE SHEAR ON THE EDGES OF THE SPECIMEN

C.DENOTES THE CLEAVAGE APPEARING REGION

t-19mm FOR SPECIMENS WtTli THICKNESS GREATER THAN 19mm

FIG. 4 ALTERNATE SHEARCLEAVAGE

8

FRACTIJRE APPEARANCE

IS : 10623 - 1983

5.4 The percent shear area of the fracture surface may be determined in the following different ways:

a>

b)

4 4

Measure the shear area of the fracture surface with a planimeter on a photograph or optical projection of the fracture surface;

Compare the fracture surface with a calibrated set of photographs of previously fractured specimens or with actual specimens of calibrated percent areas for a specific thickness;

Follow procedure as described in Appendix A; and

Use any other procedure which has been demonstrated to z;$ce results equivalent to those obtained from (a), (b) and (c)

.

6. TEST REPORT

6.1 A report of the test results shall be furnished to the purchaser and shall include as a minimum the specimen orientation in product ( trans- verse or longitudinal ), thickness, heat number, material specification, test temperature and the fracture appearance ( percent shear area ) of each specimen. If a series of specimens is broken over a range of temperature, the result shall be plotted as percent shear area versus temperature.

MEASUREMENT

APPENDIX A ( Clause 5.4 )

OF DROP WEIGHT TEAR TEST PERCENT SHEAR AREA

A-l. PROCEDURE

A-l.1 There are many methods for measuring the percent shear of DWTT specimens. Some of the methods, such as photographing and planimetering the fracture are accurate but slow; other methods, such as measuring the shear at the mid point of the specimen are rapid but not accurate enough. The procedure outlined here, is a reasonably accurate and rapid method of measuring the percent shear area.

A-1.2 The procedure to be used depends upon the configuration of the fracture surface. Figure 5 shows three representative fracture surfaces. The specimens exhibiting fracture surfaces between Fig. 5 ( Detail A ) and ( Detail B ), the shear area is calculated assuming the cleavage portion of the fracture is a third degree curve - this approximates the cleavage fracture surface configuration with reasonable accuracy. This results in the following equation which is applicable between approximately 100 and 45 percent shear or to the point where the cleavage, fracture extends

9

IS I 10623 - 1983

to the ‘one t’ line on the back end of the specimen:

Percent shear area = ( 2*8 - 2t ’ t - 3’4 AB x 100 ( 2,8 - 2t) t

where

A = the width of the cleavage fracture at the ‘one t’ line, in mm; and

B = the length of the cleavage fracture in between the ‘two t’ lines, in mm.

LtA SECTION-AA DETAIL- A 100 ‘I. SHEAR

SECTION EB DETAIL-B

APPROX. 15’1. SHEAR

SHEAR LIP t

THICKNESS v

I

I IST t

DE TAIL-C LESS THAN &Se/. SHEAR

FIG. 5 REPRESENTATIVE DWTT FRACTURE SURFACES

A-l.3 Rather than making the calculation for each specimen it is quicker to compute the data for various thicknesses and plot it. Figures 6 and 7 are example charts for determining percent shear of 7.8 mm and 8.6 mm thick material. With figures such as these it is possible to determine shear areas of specimens by measuring the A and B dimensions of the fracture surface shear areas in the range of 45 to 100 percent.

A-1.3.1 In the shear range between 45 to 0 percent, represented by the fracture surface shown in Fig. 5 ( Detail C ), the percent shear is obtained by making 3 or 4 measurements of the total shear lip thickness, averaging them and dividing by specimen thickness. This may also be tabulated. for easy determination.

10

8.76

I 740 6.25 5.00

E S 3.75

t ‘; 2.50

l-25

tt 7*80mm

?ERCENT SHEAR AREA

FIG. 6 CHART FOR DETERMINING PERCENT SHEAR FOR 7.80 mm MATERIAL

8.15

I 6 5.00 7.50 25

: 3.15 2 l 2.50

l-25 t D 6-6 mm

10 20 30 40 50 60 70 80 90 100 PERCENT SHEAR AREA

FIG. 7 CHART FOR DETERMINING PERCENT SHEAR FOR 8.6 mm MATERIAL