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“Step Out From the Old to the New”

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“The Right to Information, The Right to Live”

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“Knowledge is such a treasure which cannot be stolen”

“Invent a New India Using Knowledge”

है”ह”ह

IS 7739-6 (1975): Code of Practice for Preparation ofMetallographic Specimens, Part 6: Lead and its alloys andtheir examination [MTD 22: Metallography and HeatTreatment]

Indian CODE OF PRACTICE

ISr775!l(PartVI)-1975

Standard FOR PREPARATION OF

METALLOGRAPHIC SPECIMENS

PART VI LEAD AND ITS ALLOYS AND THEIR EXAMINATION

Metallography and Heat-Treatment Sectional Committee, SMDC 27

Chairman Representing

SHRI K. V. CEINNAPPA International Nickel ( India ) Pvt Ltd, Bombay

Members

SHRI M. ANJ~NEYULU Mining & Allied Machinery Corporation Limited,

SHRI N. V. RAQHWAN (Alternate) Durgapur

SHRI N. C. BAQOEI National Test Houae, Calcutta Saar S. N. BANEBJEE Indian Institute of Metals, Calcutta SHRI S. S. BAATNA~AR National Metallurgical Laboratory

Jamsbedpur ( CSIR ),

Da S. K. CHATTERJEE Guest, Keen, Williams Ltd, Howrah SHRI S. K. BAEU ( Alternate )

SHRI DASARATHA The Mysore Iron & Steel Ltd, Bhadravati SHRI B. HARIDASACEAR ( Al&mate )

Sns~ D. M. DAVAR Premier Automobilea Ltd, Bombay SHRI A. T. BORATE ( Alternate )

Dxz;rG DIRECTOR ( MET )-3, Ministry of Railways

CHEMIST & METALLUB~IST ( Altemate ) SEBI A. K. GUHA Directorate General of Supplier & Disposals

( Inspection Wing ), New Delhi SH~I P. C. MUSTAFI ( Alternate )

SEBI H. A. JAISINQHANI Mahindra & Mahindra Ltd, Bombay SHRI A. R. RANADIVE ( Alternate )

SHRI M. L. KATYAL Bajaj Auto Ltd, Pune DR D. M. LAKHIANI Indian Iron & Steel Co Ltd, Burnpur

SERI D. R. DASQUPTA ( A&-mate ) SHBI N. MAJUMDAB Indian Aluminium Co Ltd, Calcutta

SERI S. N. BOSE ( Altwnatc ) DR G. MUKHERJEE Hindustan Steel Ltd, Ranchi

SHRI D. K. BAQCHI ( Alternate ) SRRI A. PADMANAEAN Ashok Leyland Ltd, Madras SHRI B. M. PA1 The Alloy Steel Producers’ Association of India,

Bombay SHRI S. A. MALWADE ( Alternate )

( Continued on page 2 )

@ Copyright 1976 INDIAN STANDARDS INSTITUTION

I8 I 7799 ( Part VI ) - 1975

( Cuntimtedfrom page 1 )

Members RepIcsanting

Dx P. S. PATREAL Tate Engineering & Locomotive Co Ltd, Jamshedpur

S~rn J. C. KAPOOS ( Altewtats) SH~I N. M. RAJU Hindusten Motors Ltd, Uttarpara SXWI B. RAMA KRISHNA Indian Telephone Industries Ltd, Bangalore

Sasr J. NAQESH BEAT ( Altemufe ) SEBI V. RAMA SWAXY Ministry of Defence ( DGI ), Department of

Defence Production SEMI R. H. G. RAU Mukand Iron 8~ Steel, Bombay SHBI G. G. SAHA Ministry of Defence ( R & D ) SHEI H. N. SINon Textile Machinery Corporation Ltd, Belgharia DB L. R. VAIDYA~ATE Indian Copper Information Centre, Calcutta SHBI V. V. VIRBEAD~AYYA Directorate General of Technical Development

SHBI K. L. CEIATTEBJEE ( Altemute ) &a~ SVBHA~H WADHAVAN Murarka Engineering Works, New Delhi SHBI C. R. RAMA RAO, Director General, IS1 ( Ex-o&i0 Member)

Director ( Strut & Met )

Secretay

SHBI B. MVKHEBJI

Deputy Director ( Met ), IS1

IS:7739(Part VI)-1975

Indian Standard CODE OF PRACTICE FOR PREPARATION OF

METALLOGRAPHIC SPECIMENS

PART VI LEAD AND ITS ALLOYS AND THEIR EXAMINATION

0. FOREWORD

0.1 This Indian Standard (Part VI) was adopted by the Indian Standards Institution on 31 December 1975, after the draft finalized by the Metallography and Heat-Treatment Sectional Committee had been approved by the Structural and Metals Division Council.

0.2 The primary object of metallographic examination is to reveal the constituents and the structure of metals and their alloys by means of a microscope. Because of diversity in available equipment, wide variety of problems encountered, and the personal element, this standard gives for the guidance of the metallographer only those practices which experience has shown are generally satisfactory.

0.3 This standard is being issued in parts. This part covers polishing, etching and examination of lead and its alloys. The other parts of this code are as follows:

Part I Part IL Part HI Part IV

Part V Part VII

Part VIII Part IX

Part x Part XI

1. SCOPE

General features Electrolytic polishing Aluminium and its alloys and their examination Copper and its alloys and their examination Iron and steel and their examination Magnesium and its alloys and their examination Nickel and its alloys and their examination

Gold, silver, platinum, palladium and their alloys and their examination Tin and its alloys and their examination Zinc and its alloys and their examination

1.1 This standard (Part VI ) covers polishing, etching and examination of iead and its alloys.

IS:7739(Part VI)-1979

2. PREPARATION OF SPRCWENS

2;O Recommended methods. of selection, size, cutting, cleaning and mounting of metallographic specimens are outlined in Part I of this standard.

2.1 The preparation of lead and lead alloy specimens is difficult because their softness results in surface flow and cold working which masks the true structure. Although it is generally agreed that a surface free of cold work is almost impossible to obtain by polishing, this is now neither necessary nor particularly advantageous for common leads and alloys with but small amounts of other elements in solution since recent developments in etching make the uniform removal of cold-worked material possible. Alloys containing hard constituents, however, present more difficulty because of uneven attack by etching solutions.

22 A number of methods for preparing specimens are in regular use, the choice for a given specimen generally depending upon the alloy, the size and shape of specimen and, perhaps, the available equipment or the operator’s preference. It is always necessary, however, to remove sufficient metal to eliminate the effects of sawing, shearing, filing, or whatever means were used in securing the specimen. For the softer alloys, cutting or grinding, as described later, will be satisfactory but alloys containing hard constituents should be prepared with a microtome or its equivalent.

2.3 Lead cable sheathing and other specimens are often prepared on a machinist’s lathe, using a sharply pointed tool shaped to cut, and not flow, the metal. Cutting speeds and feeds should be slow. Still another method is to use a wood plane with a very sharp blade, set to remove the thinnest possible shaving. Samples to be prepared this way are generally clamped between two pieces of wood and the whole mass shaved down together.

2.4 The methods described above are intended to produce a surface a&able for etching for low- and high-power examination without further treatment and, when properly done, wiik produce surprisingly good results. A fine microtome surface is especially suitable for very fine i work. A light etch will then produce a smooth surface.

2.5 Use a mill file to remove all traces of other working ( saw marks, etc ) and to secure a flat surface. The surface is then ground smooth by hand on lubricated emery paper backed with plate glass. Although papers of various degrees of fineness may be used, No. 0 and 000 papers are usually sufficient. A new paper about thirty times the area of the surf- of solid specimens and eight times the diameter of tube specimens

4

IS27733 (Part VI)-1973

should be used each time. Bumps or foreign particles on the paper are removed by scrapping with a straightedge, while an abundant supply of gasoline or a solution of paraffin in kerosine is used as a lubricant. Grinding, with the specimen pressed firmly against the paper, is continu- ed until the emery is worn smooth and a bright surface-free of prominent scratches is obtained ( 5 to 7 minutes on each paper ). The specimen is etched p.fter first wiping it free of gasoline or, if another lubricant was used, cleaning in gasoline and wiping. Such surfaces will usually show sufficient, detail for examinatioc at the magnifications generally used for lead. If, after etching, it appears that further preparation is desirable grinding for about 5 minutes on No. 0000 emery paper may be helpful. (For details of grit numbers of abrasive papers, see IS : 715-1966* and IS: 28381964t. A comparative chart of grit npmbers of abrasive grains is given at Appendix A).

2.6 Polishing - Final fine polishing is not common practice with lead specimens. A suitable procedure is to polish on a wet clean, broad cloth liberally smeared with soap and using a water suspension of the finest levigated alumina. When a black smudge appears, polishing should be very carefully continued until it disappears and the surface is again bright. Scratches remaining after this operation are sometimes visible after etching but can be removed by alternately etching and polishing by hand on silk velvet well soaked with soap and alumina.

3. ETCHING REAGENTS

3.1 In Table 1 are given etching reagents commonly recommended for lead and its alloys. Etching of lead and lead alloys is not wholly independent of the method of preparatiofi, but in general the reagent used to remove thick layers of worked metal will work universally, while the others may present some difficulties. The optimum etching procedure is not only dependent on the method of preparation of the specimen, but also upon the exact composition or previous history or both. For complete elucidation of structure more than one etching reagent may be necessary, and flexibility of technique is desirable far good results. The proponents of the microtome method generally depend on a strong etchant or possibly careful swabbing to remove the layer of cold-worked metal. Emphasis is placed on the condition of the edge of the microtome knife in the determination of procedure, especially in the case of virgin leads and the softer alloys. When polishing is employed, the specimen is usually alternately polished on a velvet pad and lightly etched during the final stages until no further improvement is noted under the microscope.

+Spec&ation for coated abraaiver, glue bond ( second rhsbn ). t+&cation for waterproof silicon carbide paper.

5

TABIZ 3 BTClIUNG REAGEXTS FOR LEAD AND ITS ALLOYS

( clmue 3.1 )

IE. &JEIYO RBA~BET ComPotlITror ’

(11 (2) (3)

i) Ammonium molybdats HsMoO, ( 85 percent ) 100 g NH,OH 140 ml H.0 240 ml

ii) hfixdacids

FiigN;nd add to 60 ml *

:;a$1 acetic acid

HI0 ’

JPVtr 4 parts

16 parts

RXYAUXS

(4)

Alternately swab speci- men and wash in running water

Use freshly prepared nolutionat4Oto &*C. Immerse for 4 to 30 minu tes depending on depth of worked m e t a 1 layer. Clean with wet cotton in running water

iii) Mixed acids in glycerine ~lacsd acetic acid 1 part Use freshly prepared

Glyc&ine 1Prt solution at WC 4 parts

iv) A m m on iu m molybdate See reagents No. 1 Swab with reagent mixed acids and 2 No. 1 until structure

is clearly visible. Im- merse in reagmt No. 2 for about 6 minutes. Clean by swabbing in running water

V) A c e t i c peroxide

acid-hydrogen a) Glacial a c et i c S parts Etch 10 to 30 minutes acid

HsOs ( 9 percent) depeniE!n depth

1 part of metal layer. Clean in HNO, (sp gr l-42), if necer- ury

USE

(5) Rapid etch. Very

suitable for remov- ing thick layers of worked metal

Gives excellent detail for photographing

Used for alternate polishing and ctch- ing

Combines advantages of reagents No 1 and 2

Recommended for antimony alloyr up to 2 percent anti- mony

vi) Porchloric aid

vii) sihernimte

viii) Niwkwid(l:l)

ix) Niwic add HNO,

b) Ckcial acetic acid HsOs ( 30 percent )

3 parts Etch for 6 to 15 seconds For 1 part

lead-antimony alloya

c) Glacial acetic acid H.0, ( 30 percent )

2 parts Etch for 8 to 15 seconds For pure lead and 1 part by immersion lead-calcium alloys

zG;o‘ 60 ml Electrolytic etching Recommended for s 40 ml specimen cathode,

platmum anode antimony alloys with over 2 percent anti- mony

AgNOt ItO

Foranti-friction 5 to 10 g 95 to 90 ml

Use by swabbing metals

$:I, Etch in boiling fofution for 5 to IO mmuter

Mawc;;;opic etching for , laminations,

etc

Alternate in acid and Pure lead running water

l The use of concentrated reagents is intended, unless otherwise specified.

18 : 7739 ( Part VI) - 1975

4. EXAMINATION AND IDENTIFICATION OF CONSTITUENTS

4.1 After etching, the specimen shall be properly dried to preserve the bright surface. This is generally accomplished by rinsing quickly and carefully in a full stream of running distilled water at or just below room temperature and quickly drying in a blast of air at or just below room temperature; excess liquid on the sides of the specimen may be removed by placing the surface gently on clean, dry blotting paper for about 5 seconds. Specimens etched in certain reagents are somewhat difficult to dry properly, while some of the lead alloys are quite suscepti- ble to tarnish. Warm, humid atmospheres also present extreme difficulty and may require the use of an alkali potective film or examination while the specimen is submerged in water. The etched specimen should be preserved, if required, in a desiccator.