1、BRITISH STANDARD BS6285:1982 ISO4968:1979 Method for The macrographic examination of steel by sulphur print (Baumann method) ISO title: Steel Macrographic examination by sulphur print (Baumann method) UDC 669.14:620.183.42BS6285:1982 This BritishStandard, having been prepared under the directionof t
2、he Iron and Steel Standards Committee, was published under the authority ofthe Board of BSI and comes intoeffect on 30 September1982 BSI11-1999 The following BSI references relate to the work on this standard: Committee referenceISE/72 Draft for comment77/76856DC ISBN 0 580 12882 2 Cooperating organ
3、izations The Iron and Steel Standards Committee, under whose direction this British Standard was prepared, consists of representatives from the following: British Constructional Steelwork Association British Internal Combustion Engine Manufacturers Association British Ironfounders Association Britis
4、h Railways Board* British Steel Industry* British Steel Industry (Wire Section) Concrete Society Limited Council of Ironfoundry Associations Department of Industry (National Physical Laboratory) Electricity Supply Industry in England and Wales Engineering Equipment Users Association Federation of Ci
5、vil Engineering Contractors Institute of Quality Assurance Institution of Production Engineers Institution of Structural Engineers International Tin Research Institute Lloyds Register of Shipping National Association of Drop Forgers and Stampers Oil Companies Materials Association Process Plant Asso
6、ciation Royal Institute of British Architects Society of Motor Manufacturers and Traders Limited Steel Casting Research and Trade Association Water-tube Boilermakers Association The organizations marked with an asterisk in the above list, together with the following, were directly represented on the
7、 Technical Committee entrusted with the preparation of this BritishStandard: British Industrial Fasteners Federation Ministry of Defence Stainless Steel Fabricators Association of Great Britain Amendments issued since publication Amd. No. Date of issue CommentsBS6285:1982 BSI 11-1999 i Contents Page
8、 Cooperating organizations Inside front cover National foreword ii 1 Scope and field of application 1 2 General 1 3 Principle and aim of the test 1 4 Products and reagents 1 5 Test piece 1 6 Procedure 2 7 Test report 2BS6285:1982 ii BSI 11-1999 National foreword This BritishStandard has been prepare
9、d under the direction of the Iron and Steel Standards Committee and is identical with ISO4968:1979 “Steel Macrographic examination by sulphur print (Baumann method)” published by the International Organization for Standardization (ISO). Terminology and conventions. The text of the International Stan
10、dard has been approved as suitable for publication as a BritishStandard without deviation. Some terminology and certain conventions are not identical with those used in BritishStandards; attention is especially drawn to the following. The comma has been used throughout as a decimal marker. In Britis
11、hStandards it is current practice to use a full point on the baseline as the decimal marker. Where the words “International Standard” appear, referring to this standard, they should be read as “BritishStandard”. A British Standard does not purport to include all the necessary provisions of a contrac
12、t. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pagesi andii, pages1 and2 and a back cover. This s
13、tandard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.BS6285:1982 BSI 11-1999 1 1 Scope and field of application This InternationalStandard specifies a method (Baumann) for the macrographic exam
14、ination of steel by means of contact printing using silver salts and sulphuric acid. The method is applicable to non-alloy and alloy steels 1)of which the sulphur content is less than0,1%. 2) 2 General 2.1 The sulphur print test is essentially a qualitative test. It is inadvisable to assess the sulp
15、hur content of a given steel merely on the basis of its sulphur print. 2.2 Experience shows that the degree of darkening of the photo-sensitive emulsion is not always in proportion to the quantity of sulphides present in the metal. Certain factors may influence the macrographic attack to a greater o
16、r lesser extent; as examples, the following may be quoted: the chemical composition of the steel: the presence of certain elements modifies the type and shape of the sulphides and consequently the appearance of the image obtained, for example concentrations of titanium greater than0,1% give prints w
17、hich do not reveal sulphides; the surface condition of the sample: the presence of surface cold working may alter the image obtained; the sensitivity of the photographic paper. 2.3 The use of the test, and the conditions for interpreting the results observed, depend on the particular case: details a
18、re laid down in product standards or shall be subject to special agreement. 3 Principle and aim of the test 3.1 The aim of macrographic examination by sulphur printing is to detect, by printing on photo-sensitive paper 3)previously soaked in sulphuric acid solution, the position of areas containing
19、sulphur inclusions found in the metal invarious chemical forms and with various shapes:iron sulphide, manganese sulphides, mixedsulphides, oxy-sulphides etc. 3.2 The distribution of the sulphur-rich areas is revealed by the local release of hydrogen sulphide, causing darkening of the sensitive emuls
20、ion due to the chemical conversion of the silver halides to silver sulphide. 3.3 By examining the distribution and size of the sulphur inclusions detected by this process it is possible to make some asessment of the degree of uniformity of the metal from the section examined. Thus sulphur printing r
21、eveals chemical irregularities (segregations: for example those of a non-rimming free-cutting steel) and may reveal certain physical irregularities (for example cracks and porosity). Furthermore, sulphur printing may be used sometimes to distinguish rimming steel from killed steel and may also draw
22、attention to certain areas where tests (for example, mechanical tests) or sampling for analysis may need to be carried out. 4 Products and reagents 4.1 Photographic paper The sulphur print is made on the sensitive side of a sheet of photographic paper (or of a flat film) cut to suitable size. In gen
23、eral, the paper used is thin matt paper with a thin layer of gelatine, for example bromide enlarging papers. The clear advantage of this type of paper is that there is less tendency to slip when it is applied. 4.2 Reagents Sulphuric acid, commercial, dilute solution, having the following volumetric
24、composition 4) : 4.3 Fixing solution A commercial fixing solution or a15 to20% solution of sodium thiosulphate in water. 5 Test piece The test may be made on the product or on a test piece cut from the product. In general, this consists of a section perpendicular to the direction of rolling for prod
25、ucts such as bars, billets and rounds, or of a surface suitably selected by agreement between the parties. 1) This method may also be applied to cast irons. 2) In the case of sulphur steels (sulphur content0,1%) testing may be carried out, but with a very dilute solution of sulphuric acid. 3) The ph
26、otographic paper may be replaced by a flat film. The positive and transparent prints obtained from the flat film may be used directly to produce negative proofs. H 2 SO 4( 20 1,84g/ml) : 3volumes H 2 O :97volumes 4) Other concentrations may be used if necessary.BS6285:1982 2 BSI 11-1999 5.1 Sampling
27、 In the absence of requirements in the product standards, the number and position of the surfaces examined shall be subject to agreement between the parties. It is advisable, in particular, to locate the test surfaces away from the cut faces when cutting has been carried out by hot shearing, which d
28、eforms the fibres as well as the inclusions and may greatly offset the segregates; by flame cutting, which, in the case of hard steels, may produce local hardening, shrinkage cracks or local tempering. 5.2 Machining 5.2.1 Preparation of the test-piece surface is of prime importance in obtaining a co
29、rrect sulphur print. While rough machining, resulting in relatively coarse surfaces, may be sufficient in certain cases (routine inspection to reveal shrinkage holes, for example), it is generally required that the machining should be carried out as carefully as possible. The criteria to be observed
30、 when machining are as follows: a) cutting-tool marking should not be pronounced, for example as the result of incorrect adjustment, excessively deep cuts or heavy feeds on the lathe or the shaping machine; good results are generally obtained with a feed of approximately0,1mm; b) there should be as
31、little cold working of the surface as possible, due for example to a type of tool which is not suitable for the metal, or which is badly sharpened; to the use of unsuitable grinding wheels. 5.2.2 The main types of machining, generally used and leading to accurate prints which are more or less identi
32、cal, are grinding, with or without preliminary machining; shaping or turning, provided that the lathe is fitted with a speed adjuster. 5.2.3 A too smooth finish (mirror-type finish) makes it easier for the paper to slip on the test piece. In general, it is recommended that a surface finish with an R
33、 aof at least3,24m be obtained after machining. 6 Procedure 6.1 Immerse the photographic paper(4.1) for approximately5min in a sufficient volume of the sulphuric acid(4.2) at ambient temperature. 6.2 After removing excess acid reagent, for example by draining, apply the sensitive side of the paper,
34、still damp, to the surface to be examined, which should be clean and free from grease. As an alternative to this procedure, if the piece is small, it may be applied to the paper which has been impregnated beforehand. Ensure that there is firm contact between the piece and the paper, without any slip
35、ping, throughout the test. If necessary, weigh the piece down in order to aid contact. 6.3 To ensure good contact, eliminate air bubbles and drops of liquid between the surface of the test piece and the sheet of paper, for example by means of a rubber roller. 6.4 Determine the time of application in
36、 advance from the available data concerning the metal to be examined (chemical composition, for example) and also by the type of irregularities to be detected. It may vary from a few seconds to a few minutes. 6.5 Remove the print and wash it in running water for approximately10min, after lightly rub
37、bing it with a wad of wet cotton-wool. Immerse the print for at least10min in the fixing solution(4.3), then wash in running water for at least30min, and dry. 7 Test report The test report shall include the following information: a) the steel grade examined; b) the cast number; c) the position of th
38、e surface examined; d) the result of the test.blankBS6285:1982 ISO4968:1979 BSI 389 Chiswick High Road London W4 4AL BSIBritishStandardsInstitution BSI is the independent national body responsible for preparing BritishStandards. It presents the UK view on standards in Europe and at the international
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