Is 1608-1995 u6f41

(Superseding

IS 1521 : IS 1816 : 1979, IS 1894 : IS 2654 : 1977, IS 2655 : IS 2657 : 1964, IS 2658 : and IS 8285 : 1976 )

IS1608:1995 1972, 1972, 1964, 1964,

IS IS IS IS

1663 2078 2656 4713

: : : :

1972, 1979, 1964, 1988,

LICENSED TO ESSAR STEEL LIMITED, HAZIRA FOR INTERNAL USE AT THIS LOCATION ONLY, SUPPLIED BY BOOK SUPPLY BUREAU.

Indian Standard MECHANICAL TESTING ‘OF METALS TENSILE TESTING (Second Revision) First Reprint DECEMBER

1996

UDC 669 : 620.172

0 BIS 1995

BUREAU MANAK

OF

INDIAN

NEW DELHI

August 1995

STANDARDS

BHAVAN, 9 BAHADUR

SHAH ZAFARMARG

110002

Price Group 8

Mechanical

Testing of Metals Sectional

Committee,

MTD 3

FOREWORD This Indian Standard ( Second Revision ) was adopted by the Bureau of Indian Standards, after the draft finalized by the Mechanical Testing of Metals Sectional Committee had bien approved by the Metallurgical Engineering Division Council.

This revised standard supersedes the following Indian Standards: IS 1521 : 1972 Method for tensile testing of steel wire (first revision ) IS 1663 : 1972 Method for tensile testing of steel sheet and strip of thickness 0.5 mm to 3 mm ( first revision ) IS 1816 : 1979 Method for tensile test for light metals and their alloys (first revision ) IS 1894 : 1972 Method for tensile testing of steel tubes (first revision )’ IS 2078 : 1979 Method for tensile testing of grey cast iron (3~~1 revision ) IS 2654 : 1977 Method for tensile testing oc cbpper and copper alloys (first revision ) IS 2655 : 1964 Method for tensile testing of copper and copper alloy tubts IS 2656 : 1964 Method for tensile testing of copper and copper alloy wires IS 2657 : 1964 Method for tensile testing of aluminium and aluminium alloy tube IS 2658 : 1964 Method for tensile testing for aluminium and aluminium alloy wire of lower yield stress, proof stress and proof test for steel IS 47!3 : 1988 Method of determination at elevated temperature IS 8285 : 1976 Method for tensile test of copper and copper alloy rolled flat product In reporting the results of a test or analysis made in accordance with this standard, if final value, observed or calculated, is to be rounded off, it shall be done in accordance with IS 2 : 1960 &Rules for rounding off numerical values ( revised )‘.


This standard was first published in 1960 and subsequently revised in 1972. In this revision, this standard has been aligned with EN 10002 : 1991 ‘Tensile testing of metallic materials - Method of Assistance has also been derived from IS0 783 : 1989 ‘Metallic test at ambient temperature’. materials - Tensile testing at elevated temperature’ and IS0 6892 : 1984 ‘Metallic materials - Tensile testing’.

IS 1608 : 1995

Indian Standard MECHANICAL TESTING OF METALS TENSILE TESTING (Second Revision) 1 SCOPE 1.1 This

4.1 Elongation Increase in the original gauge length (Lo) at the end of the test. 4.2 Extension

1.2 The method of tensile tesiing of metallic foils is covered in IS 13237 : 1991 ‘Metallic foils - Tension testing’.

Increase in the extensometer gauge length (Le) at a given moment of the test.

2 REFERENCES

4.3 Gauge Length

The following Indian Standards adjuncts to this standard: IS No.

are necessary

Title

Length of the cylindrical or prismatic portion of the test piece on which elongation is measu.red at any moment during the test. 4.3.1 Original Gauge Length (L,)

Metallic materials - Verifi1 ) : 1991 cations of static uniaxial machines: Part 1 testing Tensile testing machines ( second revision ) Steel Conversion of 3803 values: Part 1 ( Part 1 ) : 1989 elongation Carbon and low ‘alloy steels ( second revision ) Steel -- Conversion of 3803 values: Part 2 ( Part 2 ) : 1989 elongation Austenitic steels ( second revision ) Metallic materials - Veri12872: 1990 fication of extensometers used in uniaxial testing 1828 (Part

3 PRINCIPLE 3.1 The test consists of straining a test piece by tensile force, generally to fracture, for the purpose of determining one OT more of the mechanical properties defined in 4.

Gauge length before application

4.3.2 Extensometer Gauge Length (L,) Length of the parallel portion of the test piece used for the measurement of extension by means of an extensometer. This length may differ from L, and shall be of any value greater than b, d, or D ( see Table 1 ) but less than L,. 4.3.3 Final Gauge Length (15”) Gauge length after rupture, the two pieces having been carefully fitted back together so that their axes lie in a straight line. 4.4 Maximum Force (F,,,) The greatest force which the test piece stands during the test ( see Annex H ).

with-

4.5 Parallel Length (~5~) Length of the reduced of the test piece.

section

parallel

portion

NOTE - The concept of parallel length is replaced by the concept of distance between grips for nonmachined test piece.

3.2 Unless otherwise specified, the test is carried out at ambient temperature between 10°C and 35°C. Tests carried out under .controlled conditions shall be made at a temperature of 23 f 5°C.

4.6 Pereeotage Elongation Elongation expressed as a percentage original gauge length (L,).

3.3 If the test is to be carried out at elevated temperature same should be specified in product standard along with permissible variations. 4 TERMINOLOGY 4.0 For the purpose of this standard definitions shall apply.

of force.

of the

4.6.1 Percentage Permanent Elongation Increase in the original gauge length of a test. piece after removal of a specified stress (aiIl& expressed as a percentage of the original gauge length (Lo).

following 1


standard specifies the method of tensile testing for metallic materials other than foils.

IS 1608 : 1995 Percentage Permanent Extension

4.6.2

moment of fracture, expressed as a percentage of the original gauge length (L,).

Wrease in the extensometer gauge length (LO) after the removal from the test piece of a specified stress (4.8) expressed as a percentage of the extensometer gauge length (f,,). Percentage

4.6.3

4.6.5

Eloltgation After Fracture (A)

Permanent elongation of the gauge length after fracture ( L,, - L, ), expressed as a percentage of the original gauge length ( L, ). NOTES 1 In the

4.6.6 case of proportional

test

pieces,

only

Extension between the start of yielding giving localized deformation and the commencement of homogeneous deformation giving smooth work hardening. It is expressed as a percentage of the extensometer gauge length (L,).

= percentage

elongation

on a gauge length

4.7 Percentage

2 In the case of non-proportional symbol A is to be supplemented cating the original gauge length millimetres, for example: .&,,nrm = percentage of 80 mm.

4.6.4 Total

plastic

(Lo)

11’3iSo.

elongation

test pieces. the by an index, indiused, expressed in

on gauge

length

(Lo)

Maximum change in cross-sectional area which has occurred during the test ( S, - S, ) expressed as a percentage of the original crosssectional area (SO). 4.8 Stress

Percentage Total Elongation at Fracture (At) elongation elongation

Reduction of Area (2)

( elastic elongation ) of gauge length

plus at the

Force at any moment during the test divided by the origmal cross-sectional area (So) of the test piece.

-

PERCENTAGE ELONGATION

c NOTE

-

S>,e Table

1 for explanation

FIG.

of refcrcnce

1

&FIN1

-I

numbers.

TIoNS

2

OF

ELONGATIOK


All.8

Percerrtage Yield Point Extension (Ae)

if the

original gauge length is other than 5’65 4 %, where S,, is the original cross-sectional area of the parallel length, the simbol A is to be supplementedby an index indicating the coefficient of proportionality used, for example:

of

Percentage Elongation at Maximum Force

Increase in the gauge length of the test piece at maximum -force, expressed as a percentage of the original gauge length (L,). A distinction is made between the percentage total elongation at maximum force (ARt) and the percentage non-proportional elongation at maximum force (A,) ( see Fig. 1 ).

IS 1608 : 1995 4.8.1 Tensile Strength (R,,,) Stress corresponding ( see Fig. 8 ).

to the maximum

force (F,)

Yield Stress

4.8.2

When the metallic material exhibits phenomenon, a point is reached during at which plastic deformation occurs any increase in the force. 4.8.2.1

without

at

the moment when first is observed ( see Fig. 2 ).

Lower yie!d stress (R,,)

The value of stress determined from the load at which a hesitation or drop of pointer is first observed. The load taken is the maximum usually recorded by the slave pointer during yield extension. NOTE - If a material which ~P.5’.~llyexhibits a yield cold-worked or heat either phenomenon is in treated condition. The yield phenomenon may not exist. In such cases proof stress ( 4.8.3.1 and 4.8 3.2 ) should SC specified.

4.8.3

Proof Stress

4.8.3.1 Proof stress of sion (RF)

non-pr )portional

Stress at which a non-proportionai extension is equal to a specified percentage of the extensometer, gauge length (15,) (see Fig. 3 ). The

Lowest value of stress during plastic yielding, ignoring any transient effects ( see Fig. 2 ).

INITIAL EFFECT

EFFECT

PERCENTAGE

0

ELONGATION

0

38)

0

PERCENTAGE

TRANSIENT

EL~~~GATION

II(b)

PE RC EN TAGE

E LONGA’IION

0

Z(c) NOTE - See Table I for explanation FIG. 2 DBFINITIONS

exten-

PECENTAGE

ELONGATION

Z!(d) of reference

n~~n~b~‘rs.

OF UPPER AND LOWER YIELD STRBSSFOR DIFFERENT TYPES OF CUR\E

3


4.8.2.2

a yield the test

Upper yield stress (R,,[)

Value of stress decrease in‘force

Apparent yield stress (R,)

4.8.2.3

IS 1608 t 1995 symbol used shall be followed by a subscript giving the prescribed percentage of the extensometer gauge length, for example: ( RPO., ).

4.8.4 Permanent Set Stress (R,) Stress at which, after removal of force, a specified permanent elongation, expressed as a percentage of the original gauge length (W, occurs ( see Fig. 5 ). The symbol used shall be followed by a suffix giving the specified percentlength, for example: age of the original ( &,.z ).

26

0

PERCENTAGE EXTENSION 9

27

t

NOTE - See Table 1 for explanation of reference numbers. FIG. 3 PROOF STRESSNON-PROPORTIONAL EXTBNSILN ( R, ) 4.8.3.2

?

Proof stress, total extension (Rt)

Stress at which total extension ( elastic extension plus plastic extension ) is equal to a specified percentage of the original gauge length (L,) ( see Fig. 4 ). The symbol used shall be followed by a suffix giving the prescribed percentage of the original gauge length, for example: ( Rt0.5 ).

PERCENTAGE EXTENSION

NOTE - See Table 1 for explanation of reference numbers. FIG. 5 PERMANENT SBT STRBSS( R, ) 5

SYMBOL AND DESIGNATIONS

Symbols and corresponding given in Table 1.

designations

are

6 APPARATUS 6.1 Testing Machine The testing machine shall be calibrated in accordance with IS 1828 ( Part 1 ) : 1991 and shall be of grade 1.0 unless otherwise specified in the product standard. 6.2 Extensometer The extensometer shall be of class 1 ( see IS 12872 : 1990 ) for the upper and lower yield stresses and the proof stress for non-proportional elongation for the other characteristics ( having higher elongations ) an extensometer of class 2 ( see IS 12872 : 1990 ) may be used. 0 NOTE numbers. FIG.

PERCENJAGE EXTENSION See Table 1 for explanation

of reference

4 PROOF STRESS,TOTAL EXTJZNSION(

Rt ) 4

The extensometer gauge length shall be not less than 10 mm and shall be centrally located in the mid-region of the parallel gauge length. The extensometer should be preferably of the type that is capable of measuring extension on both sides of a test piece and allowing the two readings to be averaged.


E

[

IS 1608:19% Table

1 Symbols

and Designations

( Clause 5 ) Reference Number’) (1)

Symbol

Unit

Designation

(2)

(3)

(4)

Test piece a

3

d

4 5 6

Lo

b

D LE Le

7 8 9 10 11

Lt LU so SU

Z

mm mm

mm mm mm mm mm mm mm% mm’ %

Thickness of a flat test piece or wail thickness of a tube Width of the parallel length of a flat test piece or average width of the !ongitudinal strip taken from a tube or width of Rat wire Diameter of the parallel length of a circular test piece or diameter of round wire or internal diameter of a tube External diameter of a tube Original gauge length Parallel length Extensometer gauge length Total length of test piece Final gauge length after fracture Original cross-sectional area of the parallel length Minimum cross-sectional area after fracture Percentage reduction of area:

Sk!-2E so 12 Elungnlinn 13

-

14

Gripped

x

100

ends

mm

Elongation

A’)

%

Percentage

15 16

Ae

Aa

% %

17

Agt

%

18 19 20 21

At -

% % % 9/o

Percentage yield point extension Percentage non-proportional elongation at maximum force, Fm Percentage total elongation at fracture at maximum force. Fm Pelccntage total elongation at fracture Specified percentage non-proportional extension Percentage total extension permanent Specified percentage set, extension or elongation

Fm

N

aLfter_fgcture: ” 0 elongation after fracture:

FCVCZ

22

Maximum

force

Yield

stress; Proof stress; Tensile strength 23

ReH

24

RCL

25

Rm

26

R,)

27

Rr

28

Rt E

N/mm* ‘) IQ/mm’ N/mm’ N/mm2 N/mm’ N/mm’ N/mm,

Upper yield stress Lower yield stress Tensile strength Proof stress ( non-proportional Permanent set stress Proof stress, total extension Modulus of elasticity

1) See Fig. 1 to 13. 2) See 4.6.3. 3) 1 N/mm* = 1 MPa.

5

extension

)


1 2

E3 1608 : 1995 Any parts of the extensometer projecting beyond the furnace shall be designed or protected from draughts so that fluctuations in the ambient temperature have only a minimal effect on the readings. It is advisable to maintain reasonable stability of the temperature and speed of the air surrounding the testing machine. 6.3 Heating 6.3.1

verified over the working temperature range at intervals not exceeding one year, the errors shall be recorded in the certification report. Verification of the temperature-measuring system shall be carried out by a method traceable to the international unit ( SI unit ) of temperature. 7 TEST

Device

Permitted Deviations

7.1 Shape and Dimensions

c>f Temperature

7.1.1 General

The heating device for the test piece shall be such that the test piece can be heated to the specified temperature, 8.

for

600°C 800°C I 000”c

&4”C for 600°C <8> f 5°C for 800°C < 6> For specified temperatures higher the permitted deviations shall be between agreement previous concerned.

than 1 OOO’C, defined by a parties the

The indicated temperatures, 6, are the temperatures which are measured at the surface of the parallel length of the test piece. The permitted deviations in temperatures shall be complied with on the original gauge length, Lo, at least until the point corresponding to the ploof stress for non-proportional extension is reached. 6.3.2

Measurement

of Temperature

The temperature measuring equipment shall have a resolution of at least 1°C and an accuracy of &2”C.

The shape and dimensions of the test pieces depend on the shape and dimensions of the metallic products, the mechanical properties of which are to be determined. The test piece is usually obtained by machining a sample from the product or a pressed blank or casting. However, products of constant cross-section ( sections, bars, wires, etc ) and also cast test bars ( that’is malleable cast iron, white cast iron, non ferrous alloys ) may be subjected to test without being machined. The cross-section of the test pieces may be circular, square, rectangular, annular or, in special cases, of some other shape. Test pieces, the original gauge length of which is related to the original cross-sectional area by the equation L, = k.dS!? are called proportional test pieces. The internationally adopted value for k is 5.65. The original gauge length shall not be less than 25 mm. When the cross-sectional area of the test piece is too small for this requirement to be met with the coefficient k value of 5.65, a higher value ( for example 1 I.3 ), for coefficient k or a non-proportional test piece may be used. In the case of non-proportional test pieces, the original gauge length (L,) is taken independently of the original cross-sectional area (S,).

Three thermocouples which are arranged at identical intervals along the parallel length of are generally sufficient to test piece, the guarantee uniformity of the temperature of the test piece. This number may be reduced if the general arrangement of the furnace and the test piece is such that, from experience, it is known that the variation in temperature of the test piece does not exceed the permitted deviations specified in 6.3.1.

The extensometer gauge length shall not be less than 10 mm and shall be centrally located in the mid-region of the parallel gauge length. 7.1.2

Machined Test Pieces

Thermocouple junctions shall make good thermal with the surface.of the test piece and be suitably screened from direct radiation from the furnace well.

Machined test pieces shall incorporate a transition curve between the gripped ends and the parallel length if these have different dimensions. The dimensions of this transition radius may be important and it is recommended that they be defined in the material specification if they are not given in the appropriate Annex ( see 7.2 ).

6.3.3 Verifca tion of the Temperature-Measuring System

The gripped ends may be of any the grips of the testing machine.

The temperature-measuring sensors and read-out

The parallel length (L,) or, in the case where the test piece has no transition curve, the free

system, equipment,

comprising shall be 6

shape

to

suit


The permitted deviations between the specified temperature, 8, and the indicated temperature, 0 are the following: *3”C

PIECE

IS 1608 : 1995 length between the grips, original gauge length (L,). 7.1.3 Xon-machined

is dependent

on the

Tezt Pieces

If the test piece consists of an unmachined length of the product or of an as-cast test bar, the free length between the grips shall be sufficient for one set of gauge marks to be at a reasonable distance from these grips. 7.2 Types

Table 2 Product Types ( Clause 7.2 ) Flat Products a Thickness mm

with in

0’1 -: thickness -

Wire, Bars and Sections with a Diameter or Side in

Annex

“1m -

< 3

A B

<4 >4

>3

D

of Test Pieces

7he selection of samples and preparation of test pieces shall be done in accordance with the requirements specified in relevant product standards. 8 PROCEDURE 8.1 Determination Area (S,)

of

Original

Cross-Sectional

The original cross-sectional area shall culated from the measurements of the priate dimensions. The accuracy of this lal‘irrfidepends on the nature and typ: test piece. It is indicated in Annexes for the different types of test pieces. 8.2 Marking the Original

If the parallel length (L,) is much in excess of the original gauge length, as, for instance, with unmachined test pieces, a series of overlapping gauge lengths shall be drawn, some of these ltngths may extend up to the grips., In some cases, it may be helpful to draw, on the surface of the test piece, a line parallel to the longitudinal axis, along which the marks are drawn. 8.3 Gripping of Test Pieces The test pieces shall be held by suitable means such as wedges, screwed holders, shouldered holders and pin holders, etc. Every endeavour shall be made to ensure that test pieces arc held in such a way that the force is applied as axially as possible. This is of particular importance when testing brittle materials or when determining proof stress ( non-proportional elongation ) or proof stress ( total elongation ) or yield stress. 8.4 Heating

of Test Piece

C

Tu brs

7.3 Preparation

The original gauge accuracy to an

be calapprocalcuof the A to D

Gauge Length (i,,)

Each end of the original gauge length shall be matked by means of fine marks or scribed lines, but not by notches which could result in premature fracture. For proportional test pieces, the calculated value of the original gauge length may be rounded off to the nearest multiple of 5 mm, provided that the difference between the calculated and marked gauge length is less than 10 percent of Lo. Annex E gives a scale for determination of the original gauge length corresponding to the dimensions of test pieces

The test piece shall be heated to the specified temperature, 19,and shall be maintained at that temperature for at least 10 min before loading. The loading shall only be started after the indications of elongation measuring the apparatus have been stabilized. During the heating, the temperature of the test piece shall not, at any moment, exceed the specified temperature with its tolerances, except by special agreement between the parties concerned. When the test piece has reached the specified temperature, the extensometer shall be reset to zero. 8.5 Loading of the Test Piece Force shall be applied so as to strain the test piece in a non-decreasing manner, without shock or sudden vibration. The force shall be applied along the specimen axls so as IO produce minimum bending or torsion in the specimen gauge length. 8.6 Determination 8.6.1

Upper

of Yield Stresses

Yield.Stress

(RBli )

8.6.1.1

The upper yield stress shall be determined as per definition given in 4.8.2.1.

8.6.1.2 The rate of stressing shall be within the !imits given in Table 3. It shall be fixed by regulating the rate of stressing in the elastic range and by maintaining the controls of the 7


The main types of test piece are defined in Annexes A to D according to the shape and type of product, as shown in Table 2. Other types of test piece can be specified in product standards.

of rectangular cross-section. length shall be marked of f 1 percent.

IS 1608 : 1995 machine at this stress is achieved.

setting

untii

the

upper

8.7 Determination

yield

8.7.1 Proof Stress ( Non-proportional Extension ) (R,)

8.6.2 Lower Yield Stress (R,I,)

8.7.1.1 The proof stress ( non-proportional extension ) shall be determined as per definition given in 4.8.3.1. The rate of stressing shall be within the limits given in Table 3. The straining rate shall not exceed 0.002 5/s.

8.6.2.1 The lower yield stress shall be determined as per definitions given in 4.8.2.2.

8.7.1.2 The proof stress ( non-proportional extension ) is determined from the force/extension by drawing a line parallel to the straight portion of the curve and at a distance from this equivalent to the prescribed non-proportional for example 0.2 percent. The percentage, point at which this line intersects the curve gives the force corresponding to the desired proof stress ( non-proportional extension ). This is obtained by dividing this force by the the test cross-sectional area of original piece (S,) ( see Fig. 3 ). The straining rate shall not exceed 0.002 5/s.

In no case shall the rate of stressing in the elastic range exceed the maximum rates given in Table 3. Table 3 Rate of Stressing 8.6.2.2,

8.6.4,8.7.2.1

and 8.9 )

Accuracy in drawing gram is essential. The an automatic recording

Modulus of Elasticity of the Material N ‘mm%

If the straight portion of the force/extension diagram is not clearly defined, thereby preventing drawing the parallel line with sufficient precision, the following procedure is recommended ( see Fig. 6 ).

< 150 000 > lSOOc4

8.6.3 Upper and &I. )

and

Lower Yield

Stresses

( X,1,

When the presumed proof stress has been exceeded, the force is reduced to a value equal to about 10 percent of the force obtained. The force is increased again until it exceeds the value obtained originally. To determine the

If the two yield stresses are determined during the same test, the conditions for determining the lower yield stress shail be complied with ( see 8.6.2.2 ). 8.6.4

the force/extension diacurve may be drawn by or manual method.

Apparent Yield Stress (Ra)

The apparent yield stress shall be determined as per definition given in 4.8.2.3. The rate of stressing shall be within limits given in Table 3. 8.6.5

Rate of Loading at Elevated Temperatures

8.6.5.1 Determination of yield stress ( upper and lower yield stresses, proof stress for nonproportional extension ) The strain rate of the parallel-sided length of the test piece, from the beginning of the test to the yield stress to be determiiled, shall be between O*OOl min-1 and 0.005 min-1. In the case of machines unable to achieve the required strain rate, the stress rate shall be set so that the requirement that the strain rate be smaller than 0.003 min-1 is coniplied with over the elastic range. In no case shall the stress rate in the elastic range exceed 300 N/ ( mm*.min ).

+/-SPECIFIED TIONAL

NON-PROPoREXTENSION

FIG. 6 PROOF STRESS,NON-PROPORTIONAL EXTENSION ( Rt )

8


8.6.2.2 If only the lower yield stress in being determined, the rate of straining during yield of the parallel length of the test piece shall be between O*OOO25/s and 0.002 5/s. The straining rate with the parallel length shall be kept as constant as possible. If this rate cannot be regulated directly, it shall be fixed by regulating the rate of stressing just before yield begins, the controls of the machine not being further adjusted until completion of yield.

( Clauses 8.6.1.2,

of Proof Stress

IS X608:-lP!6

NOTE -

PERCENTAGE EXTENSION

See Table I for explanation FIG.

of reference

numbers.

7 LOWER YIELD STRESS( ReL )

ELONGATION

NOTE -

See Table 1 for explanation

of reference

numbers.

FIG. 8 MAXIHUM FORCE( &, ) desired proof stress, a line is drawn.through the hysteresis loop. A line is then drawn parallel to this line, at a distance from the origin of the curve, measured along the abscissa, equal to the prescribed value of the non-proportional percentage. The intersection of this parallel !ine and the force/extension curve gives the force corresponding to the proof stress. This is obtained by dividing this force by the original cross-sectional area of the test piece S,, ( see Fig. 6 ).

8.7.1.3 The property may be obtained without plotting the force/extension curve by using automatic device ( microprocessor, etc ). 8.7.1.4 See 8.6.5. 8.7.2 Proof Stress, Total Extension (Rt) 8.7.2.1 The proof stress ( total extension ) shall be determined as per definition given in 4.8.3.2. The rate of stressing shall be within the limits given in Table 3. 9


0

8.7.2.2 The proof stress ( total extension ) is determined on the force/extension diagram by draning a line parallel to the ordinate axis ( force axis ) and at a distance from this equivalent to the prescribed total percentage extension. The point at which this line intersects the curve gives the force corresponding to the desired proof stress. This is obtained by dividing this force by the original crosssectional test piece (S,) area of the ( see Fig. 4 ).

8.7.2.3 The property may be obtained without plotting the force/extension curve by using automatic device ( microprocessor, etc ). of Teas&

Strength (R,)

8.8.1 The tensile strength

shall be determined $s per definition given in 4.8.1.

8.8.2 In the plastic range, the straining rate of parallel length shall not exceed OGISls. In the elastic range, if the test does not include the determination of a yield stress ( or proof stress ), the speed of the machine may reach the maximum permitted in the plastic range. 8.8.3 In the special case of zinc, the rate shall be within ON)l/s to 0.003/s.

straining

8.8.4 Rate of Loading at Elevated Temperature If only the tensile strength is to be determined, the strain rate of the test piece shall be between O-02 min-1 and 0.20 min-1. If a yield stress is also determined on the same piece, the change of the stress rate required in 8.6.5.1 to the rate defined in the paragraph above shall be monotonic. The above rate shall also be valid for testing of lead at ambient temperature. 89 Method stress (R,)

of

Verification

tensile

of Pemmncat

after Fracture

(A)

8.10.1 Percentage

of

Percentage

elongation after shall be determined in accordance definition given in 4.6.3.

This measurement is, in principle, valid only if the distance between the fracture and the nearest gauge mark is not less than one-third of the original gauge length (L,,). However, the is valid, irrespective of the measurement position of the fracture, if the percentage elongatton after fracture reaches at least the specified value and this shall be stated in the test report ( see Annex F ). 8.10.2 For machine capable of measuring extension at fracture using an extensometer, it is not necessary to mark the gauge lengths. The elongation is measured as the total extension at fracture, and it is therefore necessary to deduct the eiastic extension in order to obtain percentage elongation after fracture. In principle, this measurement is only valid if fracture occurs within the extensometer gauge length (~5~). The measurement is valid regardless of the position of the fracture cross section if the percentage elongation after fracture at least reaches the specified value and this shall be stated in the test report.

Set

Unless otherwise specified, the test piece is subjected for IO to 12 seconds to a force corresponding to the specified stress at the rate not exceeding that given in Table 3. After removing the force, that the permanent set elongation is not more than the percentage specified. 8.10 Determination

Elongation after fracture ( L, - L, ) shall be determined to the nearest 0.25 mm with a measuring device with 0, I mm resolution and the value of percentage elongation after fracture shall be rounded to the nearest 0.5 percent. If the specified minimum percentage elongation is less than 5 percent, it is recommended that special precautions be taken when determining elongation.

Elongation

NOTE - If the product standard specifies the determination of percentage elongation after rupture for a given length, the extensometer gauge length shall be taken as equal to this length.

8.10.3 If so permitted

by the product standard, elongation may be measured over a given fixed length and converted to proportional gauge length using conversion formulae or tables as agreed before the commencement of testing [for example as in IS 3803 ( Part I ) and IS 3803 ( Part 2 )I.

fracture’ with the

For this purpose, the two broken pieces of the test piece are carefully fitted back together so that their axes lie in a straigiit line.

NOTE possible

of percentage elongation are the gauge length or extensometer gauge length, the shape and area of the cross section are the same or when the coefficient of proportionality (k) is the same.

8.10.4

10

Comparison only when

In order to avoid having

to

reject

test


8.8 Determination

Special precaution shall be take! to ensure proper between the broken parts of the test piece when measuring the final gauge length. This is particularly important in the case of test pieces of small cross-section and test pieces having low elongation values.

zs 1688 : 199s 8.11 Determinatierr of Percentage Reduction of Area (Z) The percentage reduction of area shah be determined as per the definition given in 4.7.

pieces in which fracture may occur outside the limits specified in 8.10.1, the method based on the subdivision of Lo into n equal parts may be used, as described in Annex G.

ANNEX

A

( Clausts 7.2, 8.1 and Table 2 ) TYPES OF TEST PIECE TO BE USED FOR THIN PRODUCTS f SHEETS. STRIPS AND ’ FIATS BETWEEN O-1 aAND 3 mm THICK ) A-Z DIMENSIONS

OF THE TEST PIECE

The

parallel

AI SHAPE OF THE TEST PIECE

than

b L, + 2.

Generally, the test piece has gripped ends which are wider than the parallel length. The parallel length (La) shall be connected to the ends by means of transition curves with a radius of at least 20 mm ( see Fig. 9 ). The width of these ends shall be at least 20 mm and not more than 40 mm.

length h + 2b shall always there is insufficient material.

By agreement, the test piece may also consist of a strip with parallel sides. For products of width equal to or less than 20 mm, the width of the test piece may be the same as that of the product.

length

shall

In

case

not of

FIG.

less

dispute,

the

be used unless

In the case of parallel-sided test pieces less than 20 mm wide, and unless otherwise specified in the product standard, the original gauge length (L,) shall be equal to 50 mm. For this type of test piece, the free length between the grips shall be equal to Lo + 36. The preferable dimensions of non-proportional test piece are given in Table 4. However, if required in the product specification, any other type of test piece may also be used.

L

NOTE - See Table 1 for explanation

be

of reference numbers.

9 MACHINBDTEST PIBOBSOF RECTANGWLARCROSS-SECIION


A-0 For products of less than 0.5 mm thickness, special precautions may be necessary.

Table 4 Dimensions of Teat Pieces ( Clause A-2 ) All dimensions in millimcires. PamUele~engtb,

Test Piece

Width

Tppe

b

lo

J.c

Pree Length Betweea th Grips for Parallel Side Test Piece, Min

1

12’5 _I 0’1

50 +_ 0’1

75

87’5

2

20

+ 0-J

80 f 0’1

90

Orig~;h~tchpuge

140

3

25

f 0.1

100 f 0’1

115

150

4

40

rf: 0’1

160 f 0’1

180

240

A-4 DETERMlNATION OF THE ORIGINAL CROSS-SECTIONAL AREA (So) The original cross-sectional calculated from measurements of the test piece.

area shall be of the dimensions

The error in determining the original crosssectional area shall not exceed f 2 percent. As the greatest part of this error normally results from the measurement of the thickness of the test piece, the error in measurement of the width shall not exceed f 0.2 percent.

ANNEX B ( Clauses7.2, 8.1 and Table 2 ) TYPES OF TEST PIECE TO BE GSED IN THE CASE OF WIRE, BARS AND SECTIONS WITH A DIAMETER OR THICKNESS OF LESS THAN 4 mm elongation NOTE - In cases where fhe percentage after fracture is not to be determined, a distance between the grips of at least 50 mm may be used.

B-l SHAPE OF THE TEST PIECE The test piece generally consists of an unmachined portion of the product ( see Fig. 10 ). B-2 DIMENSIONS

B-3 PREPARATION

OF THE TEST PIhCE

The original gauge length (Lo) shall bt taken as 200 f 2 mm or 100 f 1 mm. The distance between the grips of the machine shall be equal to at least Lo + 50 mm, that is, 250 mm and except in the case of 150 mm respectively, small diameter wires where this distance can be taken as equal to Lo.

OF TEST PIECES

If the product is delivered coiled, care shall be taken in straightening it. B-4 DETERMINATION OF THE ORIGINAL CROSS-SECTIONAL AREA (So) The original cross-sectional area (S,,) shall be determined to an accuracy of fl percent. For products of circular -cross-section, the

12


A-3 PREPARATION OF TEST PIECES The test pieces are prepared so as not to affect the properties of the metal. Any area which have been hardened by shearing or pressing shall be removed by machining. For very thin material, it is recommended that strips of identical widths should be cut and assembled into a bundle with intermediate layers of a paper which is resistant to the cutting oil. It is recommended that each small bundle of strips be assembled with a thicker strip on each side, before machining to the final dimensions of the test piece.

IS 1608:1995 original cross-sectional area may be calculated from the arithmetic mean of two measurements carried out in two perpendicular directions.

r;.

The original cross-sectional area may be determined from the mass of a known length and its density.

_.

1 .-_i

I

I

.I

I

r-• *-.

1

..A

..

I

I 0

e

1 ..-:

5

NOTES 1 The shape of the test piece heads is given

2 Ste Tab!e 1 for explanation FIG.

of reference

only as a guide. numbers.

10 Tss-r PIECESCOMPRISING A NON-MACHINEDPORTION OF IHB PRODUCT

ANNEX

C

( Clauses 7.2, 8.1 and Table 2 ) TYPES OF TEST PIECE TO BE USED IN THE CASE OF SHEETS AND FLAT THICKNESS EQUAL TO OR GREATER THAN 3 mm, AND WIRE, BARS AND SECTIONS OF DIAMETER OR THICKNESS EQUAL TO OR GREATER THAN 4 mm C-l

In general, the diameter of the parallel length of machined cylindrical test ‘pieces shall be not less than 4 mm.

SHAPE OF THE TEST PIECE

In general, the test piece is machined and the parallel length shall be connected by means of transition curves to the gripped ends which may be of any suitable shape for the grips of the test machine ( see Fig. 11 ), Sections, bars, etc, if required.

may be tested

C-2 DIMENSIONS C-2.1 Parallel

OF THE TEST PIECE

Length of Machined

Test Piece

The parallel lengtli (~5,) shall be at least equal to: d . m the case of test pieces with a) L + T

unmachined

The cross-section of the test piece may be circular, square, rectangular or, in special cases, of another shape.

circular cross-section; and b) L, + 1*5/S, in the case of prismatic test pieces. Depending on the type test piece, the length Lo + 2d or L, + 2/S, shall be used in cases of dispute, unless there is insufficient material.

For test pieces with a rectangular cross-section, it is recommended not to exceed a ratio of 8 : 1 between the width and thickness of the test piece. 13


r:.

1s 1608 : 1995 C-2.2

Length of Unmachined

where k is equal to 5.65 which gives Lo = 5d in the case of test piece? of circular cross-section. Test pieces of circular cross-section should preferably have the dimensions given in Table 5.

Test Piece

The free length between the grips of the machine shall be adequate for the gauge marks to be a reasonable distance from these grips. C-2.3

Original

C-2.3.2

Gauge Length (L,)

Non-proportional test pieces may specified by the product standard.

Proportional Test Pieces

C-2.3.1

Non-proportional Test Pieces if

C-3 DETERMINATION OF THE CROSSSECTIONAL AREA (S,) The original cross-sectional area shall be calculated from measurements of this appropriate dimensions, with an error not exceeding + 0.5 percent on each dimension.

As a general rule, proportional test pieces are used where the original gauge length (L,) is related to the original cross-sectional area (S,) by the equation L,=kd/

Cross-Section

Test Pieces

( Clause C-2.3.1 ) Diameter (4 mm

Original Cross-

Sectional

Original Gauge

Area (so)

Length

mma

(lo)

Minimum Parallel Leogth

mm

Total Length

(lc)

mm

mm on the method of

22’5 2 0’25

400

117’5

& 1’1

124

Depends

20

+ 0’20

314

100

fixing

f

200

8C

‘I 1’0 I_ 0’8

110

16

88

machine

14 10

& 0’15 f 0’10

150 78’5

70 50

i_ 0’70 f 0’5

77 55

Lt > LC + 2d

5 4

t *

0’15

0’05 0’05

19’6

25

+ 0’25

27’5

12 5

20

I

22

0’2

I-‘ i.

b

4

NOTE -

The shape

of the test piece beads is given only as a guide.

FIQ.

11 PROPORTIONAL 14

TEST

PIECH

the

(Lt)

test grip.

piece

in the

In principle

or 4d


Table 5 Circular

be used

IS 1608: 1995

ANNEX ( Claws

D

7.2, 8.1 and Table 2 )

TYPES OF TEST PIECE TO BE USED IN THE D-l

SHAPE OF THE TEST PIECE

The test piece shall consist either of a length of tube or a longitudinal or transverse strip cut from the tube and having the full thickness of the tube wall ( see Fig. 12 and 13 ), or of a test piece of circular cross-section machined from the wall of the tube.

D-2 DIMENSIONS D-2.1

Length

OF THE TEST

D-3 DETERMINATION OF THE ORIGINAL CROSS-SECTIONAL AREA, S, The original piece shall * 1 percent.

cross-sectional be determined

area of to the

the test nearest

The original cross-sectional area of the length of tube or longitudinal or transverse strip may be determined from the mass, length and density of the test piece. The original cross-sectional area, S,, of a test piece consisting of a longitudinal strip shall be calculated using the following equation:

PlECE

of Tube

The length of tube may be plugged at both ends. The free length between each plug and the nearest gauge marks shall exceed D/4. In cases of dispute, the value D shall be used as long as there is sufficient material. The length of the plug projecting beyond the grips of the machine in the direction of the gauge marks shall not exceed the external diameter of the tube, and its shape shall be such that it does not impair the gauge length elongation. D-2.2 Longitudinal

or Transverse

Strip

The parallel-sided portion of the longitudinal strips shall not be flattened but the gripped ends may be flattened for gripping in the testing machine.

where a is the thickness b is the average D is the external

The sampling of the test pieces specified in the product standard.

shall

of Tube be

as

width

of the strips;

diameter.

The following simplified equations for longiiudinal test pieces: So = ab

Transverse or longitudinal test piece dimensions other than those given in Annexes B and C can be as specified in the product standard. taken Special precautions shall be when straightening the transverse test pieces. D-2.3 Machined Circular Cross-Section Wall

of the tube wall;

l +

(jD

(

In the case of cross-sectional follows:

used

2a

< 0.25

< 0.17

a length of tube, the original area, So, shall be calculated as

&=mz(D--a)

IS

+

be

D”‘__ )j when

-;S, = ab when

can


Machined transverse, longitudinal and circular cross-section test pieces are described in Annex A for tube wall thickness less than 3 mm and in Annex C for thickness equal to or greater than 3 mm. The longitudinal strip is generally only used for tubes with a wall thickness of more than O-5 mm.

CASE OF TUBES

NOTE -

See Table 1 for explanation

of reference

numbers.

FIG. 12 TEST PIECBCOMPRISINGA LENGTH OF TUBE

FIG. 13 TEST PIECECUT FROM A

16

TUBE


NOTES 1 The shape of the test piece heads is given only as a guide. 2 See Table 1 for explanation of reference numbers.

Is1608:19!M ANNEX E ( Clause 8.2 ) NOMOGRAM FOR CALCULATJNG THE GAUGE LENGTHS OF TEST PIECES OF RECTANGULAR CROSS-SECTION

Example of use b = 21 mm

a=

15.5mm

L, = 102mm

NOTES 1 The error in reading Lo. which is less than f 1 percent, means that this nomogram can be used in all cases without further calculation. 2 The error in reading Lo may be greater than 1 percent, meaning that in some cases the desired accuracy is not obtained; it is then preferable to calculate the product of a and b directly.

E-2 CONSTRUCTION OF THE NOMOGRAM three parallel equidistant lines which will be the axes for the logarithmic scales. These shall be graduated logarithmically such that loglo 10 is represented by 25Omm; the three scales increase towards the top of the page. Place points 20 and 10 approximately at half scales. the two height on the outer points 10 on each of the outer scales. Draw

The intersection of this line and the central scale axis gives the point 56 5 on the gauge length (Lo) scale along the left-hand side of the central axis. The cross-sectional area (S,) scale right-hand side of the central point 56.5 corresponds to the point scale, which is graduated such that represented by 125 mm, that is, half used for the other scales.

17

is on the axis. The 100 on this loglo 10 is the distance


This nomogram ( see Fig. 14 ) has been constructed using the alignment method. E-l METHOD OF USE Carry out the following steps: a) On the outer scales, select points a and b representing the thickness and the width of the rectangular test piece; b) these two points with a line ( length of thread or edge of a ruler ); c) Read off the corresponding gauge length from the left-hand of the two centre scales, at the intersection of this line with the central scale axis.

IS 1608:.3995

WIDTH

“RIG~EANL&UGE

b mm

~~=5.65fi

ORIGNAL CROSS SECTIONAL AREA

mm

THICKNESS

s,=abmm*

amm

60

I_ to 9 LB

100 90 80 70 60 10

50

9

40

8

30

7 i

20 6

4 FIG.

14 THB NOMOGRAM

18

-7


200

IS 1608 : 1995

ANNEX F ( Clause 8.10.1 ) PRECAUTIONS TO BE TAKEN WKEN MEASURING THE PERCENTAGE ELONGATION AFTER FRACTURE IF THE SPECIFIED VALUE IS LESS THAN 5 PERCENT

Prior to the test a very small mark shall be made near one of the ends of the parallel length. Using a pair of needle-pointed dividers set at the gauge length, an arc is described with the mark as the centre. After fracture. the broken test piece shall be placed in a fix&e and axial compressive force applied, preferably by means of a screw, just sufficient to hold the pieces

together firmly during measurement. A second arc of the same radius shall then be described from the original centre, and the distance between the two scratches measured by means of or other suitable a measur.ing microscoDe instrument. ‘in order to iender the fine scratches more easily visible, a suitable dye film may be applied to the test piece before testing.

MEASUREMENT OF PERCENTAGE ELONGATION AFTER FRACTURE SUB-DIVISION OF THE ORIGINAL GAUGE LENGTH

To avoid having to reject test pieces when the position of the fracture does not comply with the conditions of 8.10.1 the following method may be used, by agreement:

intervals beyond Y; calculate the percentage elongation fracture using the equation

a) Before the test: sub-divide the original gauge length, LO, into N equal parts:

A

b) After rhe rest: use the symbol X to denote the gauge mark on the shorter piece and the symbol Y to denote the division mark on the longer piece which is nearest to being the same distance from the fracture point as the gauge mark X (see Fig. 15 ). If n is the number of intervals between Xand Y, the elongation after fracture is determined as follows: 1) if N -n is an even number [ see Fig. 15 ( a ) 1, measure the distance between X and Y and the distance from Y to the graduation mark 2 located N-n 2

-

XY + 2YZ -----Lo

N--n-l

and 2

X NOTE

-

Y The shape

x *oo

N----n+1 2

intervals beyond Y; calculate the percentage elongation fracture using the equation A-

XY+

YZ'+Yz'-LL,

x

after

1oo

LO N

1

?fF--Qq I-_ !

Lo

after

2) if N--n is an odd number [ see Fig. 15 ( b ) ], measure the distance between X and Y and the distance from Y to the graduation marks Z’ and Z’ located respectively

N

I-

.- -

BASED ON

-!

2

of the test piece

heads

is given

for information

oniy.

FIG. 15 EXAMPLB OF ELONGATION MBASUREMENT AFTBR FRACTURB

19


ANNEX G ( Clause8.10.4 )

IS 1608: 1995

ANNEX H ( ClausG4.4 ) PRECAUTIONS RECOMMENDED WHEN MEASURING THE TENSILE STRENGTH OF MATERIALS SHOWING A SPECIAL YIELD PHENOMENON

For materials showing a special yield phenomenon the stress corresponding to the upper yield point, Rew, may be higher than any value of the stress after that point ( second maximum; see Fig. 16 ). In those cases, it is necessary to

select one of the two maximum values for the calculation of the tensile strength. The chosen maximum should be that specified in the product standard or by agreement between the parties concerned.

20


FIG. 16

Bureau of Indian

Standards

BIS is a statutory institution established under the Bureau oflndian StandardsAct, 1986 to promote harmonious development of the activities of standardization, marking and quality certification of goods and attending to connected matters in the country. Copyright

BIS has the copyright of all its publications. No part of these publications may be reproduced in any form without the prior permission in writing of BIS. This does not preclude the free use, in the course of implementing the standard, of necessary details, such as symbols and sizes, type or grade designations. Enquiries relating to copyright be addressed to the Director (Publications). BIS. Review of Indian

Standards

This Indian Standard has been developed from Dot No: MTD 3 ( 3870 ). Amendments

Amend No.

Issued Since Publication

Text Affected

Date of Issue

BUREAU

OF

INDIAN

STANDARDS

Headquarters: Manak Bhavan. 9 Bahadur Shah Zafar Marg, New Delhi 110002 Telephones : 323 01 31, 323 94 02, 323 83 75

Telegrams: Manaksanstha ( Common to all offices )

Regional Offices:.

Telephone

Central : Manak Bhavan. 9 Bahadur Shah Zafar Marg NEW DELHI 110002

I 323 76 17 323 3841

Eastern : l/14 C. I. T. Scheme VII M, V. I. P. Road, Maniktola CALCUTTA 700054 Northern : SC0 335-336, Sector 34-A, CHANDIGARH 160022 Southern : C. I. T. Campus, IV Cross Road, MADRAS 600113 Western : Manakalaya, E9 MIDC, Marol, Andheri (East) MUMBAI 400093

3378499,3378561 337X626,3378662 I 60 38 43 60 20 25 I 235 02 16,235 04 42 235 15 19,235 23 15 8329295,8327858 8327891,8327892

BHUBANESHWAR. BHOPAL. BANGALORE. Branches : AHMADABAD. HYDERABAD. GUWAHATI. FARIDAB AD. GHAZIABAD. COIMBATORE. PATNA. THIRUVANANTHAPURAM. KANPUR. LUCKNOW. JAIPUR.


Amendments are issued to standards as the need arises on the basis of comments. Standards are also reviewed periodically; a standard along with amendments is reaffirmed when such review indicates that no changes are needed; if the revie;: indicates that changes are needed, it is taken up-for revision. s of Indian Standards should ascertain that they are in possession of the latest amendments or edition by referring to the latest issue of ‘BIS Handbook’ and ‘Standards : Monthly Additions’.

,.,

, ,

AMENDMENT

NO. 1 MAY 2002 TO IS 1608:1995 MECHANICAL TESTING OF METALS — TENSILE TESTING

(Page 14, Table 5 ) — Substitute the following for the existing table: Table 5

Diameter (d)

Or~mal Cross-

Circular Cross-Section ( Clause C-2.3.1) Original Gauge Length (L)

Minimum Parallel Length (L)

Test Pkces

Total Length (L,)

Minimum

Transition Radius (r)

Area (.%) mm

22.5?0.25 20 f 0.20 16 f0.15 1410,15 Ioto,lo 5 f 0.05 4 i 0,05

(MTD3)

m’ 397.8 314 201.1 154.0 78.5 19.6 12.5

MM

112.5t 1.1 100i 1.0 80 k 0.8 7(3* 0.70 513i ().5 25* 0.25 20 k ().2

MM

124 110 88 77 55 27.5 22

mm

mm

Depends on the method of fixing the test piece in the machine grip. In principle

23.5 15 13 10 8 5 4

~> L+2da4d


( Second Revision)

Reprography Unit, BIS, New Delhi, India

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