1、BSI Standards PublicationBS ISO 16574:2015Determination of percentageof resolvable pearlite in highcarbon steel wire rodBS ISO 16574:2015 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of ISO 16574:2015.The UK participation in its preparation was entrusted to Technic
2、alCommittee ISE/101/7, Methods of physical and metallographictesting.A list of organizations represented on this committee can beobtained on request to its secretary.This publication does not purport to include all the necessaryprovisions of a contract. Users are responsible for its correctapplicati
3、on. The British Standards Institution 2015.Published by BSI Standards Limited 2015ISBN 978 0 580 80113 6ICS 77.040.99Compliance with a British Standard cannot confer immunity fromlegal obligations.This British Standard was published under the authority of theStandards Policy and Strategy Committee o
4、n 30 September 2015.Amendments/corrigenda issued since publicationDate T e x t a f f e c t e dBS ISO 16574:2015 ISO 2015Determination of percentage of resolvable pearlite in high carbon steel wire rodDtermination du pourcentage de perlite rsoluble dans les fils machine en acier haut carboneINTERNATI
5、ONAL STANDARDISO16574First edition2015-09-15Reference numberISO 16574:2015(E)BS ISO 16574:2015ISO 16574:2015(E)ii ISO 2015 All rights reservedCOPYRIGHT PROTECTED DOCUMENT ISO 2015, Published in SwitzerlandAll rights reserved. Unless otherwise specified, no part of this publication may be reproduced
6、or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below or ISOs member body in the country of the requester.ISO c
7、opyright officeCh. de Blandonnet 8 CP 401CH-1214 Vernier, Geneva, SwitzerlandTel. +41 22 749 01 11Fax +41 22 749 09 47copyrightiso.orgwww.iso.orgBS ISO 16574:2015ISO 16574:2015(E)Foreword ivIntroduction v1 Scope . 12 Normative references 13 Terms and definitions . 14 Symbols and abbreviated terms .
8、15 Principle 26 Selection and preparation of samples 26.1 Test location 26.2 Grinding and polishing . 26.3 Etching . 27 Evaluation of the percentage of resolvable pearlite 37.1 Parameters of optical microscope 37.2 Determination of measuring field of view. 37.2.1 Determination of measuring locations
9、 . 37.3 Measuring methods 47.3.1 Manual point count method . 47.3.2 Automatic image analysis method 47.4 Reporting of results 4Bibliography 5 ISO 2015 All rights reserved iiiContents PageBS ISO 16574:2015ISO 16574:2015(E)ForewordISO (the International Organization for Standardization) is a worldwide
10、 federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that
11、committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.The procedures used to develop this documen
12、t and those intended for its further maintenance are described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the different types of ISO documents should be noted. This document was drafted in accordance with the editorial rules of the ISO/IEC Directives,
13、 Part 2 (see www.iso.org/directives). Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of any patent rights identified during the development
14、of the document will be in the Introduction and/or on the ISO list of patent declarations received (see www.iso.org/patents). Any trade name used in this document is information given for the convenience of users and does not constitute an endorsement.For an explanation on the meaning of ISO specifi
15、c terms and expressions related to conformity assessment, as well as information about ISOs adherence to the WTO principles in the Technical Barriers to Trade (TBT) see the following URL: Foreword - Supplementary informationThe committee responsible for this document is ISO/TC 17, Steel, Subcommitte
16、e SC 7, Methods of testing (other than mechanical tests and chemical analysis).iv ISO 2015 All rights reservedBS ISO 16574:2015ISO 16574:2015(E)IntroductionThis test method produces an estimate of the percentage of pearlite resolvable at 500x magnification in wire rod as a function of the cooling me
17、thod after hot rolling to rod. The drawability of high-carbon pearlitic rod is influenced by the amount of resolvable pearlite present. As the percentage of resolvable pearlite increases, drawability decreases. The methods are used to check if the content of resolvable pearlite can fulfil the requir
18、ement of the wire rod with improved characteristics intended for drawing. ISO 2015 All rights reserved vBS ISO 16574:2015BS ISO 16574:2015Determination of percentage of resolvable pearlite in high carbon steel wire rod1 ScopeThis International Standard defines resolvable pearlite and specifies two m
19、ethods of determining the percentage of resolvable pearlite.The methods are applicable for wire rod made from control cooling steel with carbon content greater than 0,65 % C.2 Normative referencesThe following documents, in whole or in part, are normatively referenced in this document and are indisp
20、ensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.ISO 9042, Steels Manual point counting method for statistically estimating the volume fraction of a constituent
21、with a point gridISO 16120-1, Non-alloy steel wire rod for conversion to wire Part 1: General requirements3 Terms and definitionsFor the purpose of this document, the terms and definitions given in ISO 9042 and ISO 16120-1 apply.4 Symbols and abbreviated termsThe symbols and corresponding designatio
22、ns are given in Table 1.Table 1 Symbols and designationsSymbol DesignationO1 the 1st measuring locationO2 the 2nd measuring locationO3 the 3rd measuring locationO4 the 4th measuring locationOi the ithmeasuring location, i = 1,2,3 and 4Si1percentage of resolvable pearlite in the first field of view o
23、f the Oi measuring locationSi2percentage of resolvable pearlite in the second field of view of the Oi measuring locationSi3percentage of resolvable pearlite in the third field of view of the Oi measuring location,Saverage percentage of resolvable pearlite in the cross-section of wire rodINTERNATIONA
24、L STANDARD ISO 16574:2015(E) ISO 2015 All rights reserved 1BS ISO 16574:2015ISO 16574:2015(E)5 Principle5.1 This International Standard defines resolvable pearlite as pearlite where the ferrite and iron carbide lamellae can be observed at 500x magnification under optical microscopy with 0,8 or highe
25、r numerical aperture. The light source shall typically be white light, but another light source can be used.5.2 Resolvable pearlite is revealed by chemical etching of a polished section of the wire rod using an appropriate etchant. The choice of etchant shall refer to 6.3.5.3 This International Stan
26、dard specifies two methods of measuring the percentage of resolvable pearlite: manual point count method and automatic image analysis method.5.3.1 The manual point count method: a grid with a number of regularly arrayed points, which can be a clear plastic test grid or eyepiece reticule, is superimp
27、osed over the image, or a projection of the image, produced by a light microscope, and the number of points falling within the constituent of interest are counted and divided by the total number of grid points yielding a point fraction, usually expressed as a percentage, for that field.5.3.2 Automat
28、ic image analysis method: constituents with different microstructure are separated by grey-level intensity differences; for example, pearlites with smaller width between ferrite and iron carbide lamellae are darker than pearlites with bigger width. Thus, the measurement of the content of different c
29、onstituents can be made on each field by the image analyser on the nature of the discriminated picture point elements in the image.5.3.3 In case of a dispute, manual point count method shall be the referee method.6 Selection and preparation of samples6.1 Test locationIf the order, or the Internation
30、al Standard defining the product, does not specify the number of specimens and the point at which they are to be taken from the product, these are left to the manufacturer. It is recommended that two or more sections be assessed. Care shall be taken to ensure that the specimens are representative of
31、 the bulk of the product.Unless otherwise stated by the product standard or by agreement with the customer, the polished face of the specimen shall be transversal.6.2 Grinding and polishingThe specimens should be prepared metallographically using a well-conceived method, starting with sectioning wit
32、h a device that imparts minimal damage, mounting with a good resin with either a hot compression mounting press or cast resins, followed by an appropriate sequence of grinding and polishing steps, finishing with an abrasive of at least 1 m, to yield a flat surface with minimal preparation-induced da
33、mage. After polishing, the specimen should be carefully washed with water, cleaned with alcohol and finally dried.6.3 EtchingThe following two etchants are recommended:a) a picral etchant, which is a solution of 4 g of picric acid in 100 ml of ethanol;b) a nital etchant, which is a solution of a 2 m
34、l of nitric acid (20= 1,33 g/ml) in 100 ml of ethanol.2 ISO 2015 All rights reservedBS ISO 16574:2015ISO 16574:2015(E)NOTE Nital is orientation sensitive and can reveal the pearlite in different colonies in different contrast. Picral can reveal pearlite uniformly and can be superior to nital for mos
35、t high carbon wire rod.The polished surface is etched at ambient temperature in the etching solution for a minimum of 10 s or until the surface is etched clearly.After etching, wash the specimen under a stream of lukewarm water to stop the etching reaction and to remove the etchant from the surface.
36、 Then, squirt ethanol onto the surface to displace the water and dry the specimen using either clean compressed air or a flow of hot air from a device similar to a hair dryer or a hand dryer. If bleed out occurs during drying, it may be necessary to clean the mounted specimen in an ultrasonic cleane
37、r.7 Evaluation of the percentage of resolvable pearlite7.1 Parameters of optical microscopeThe etched surface shall be observed with an optical microscope using the following conditions:a) magnification: 500x;b) numerical aperture: 0,8 or higher;c) light source: white or another light source.7.2 Det
38、ermination of measuring field of view7.2.1 Determination of measuring locationsThe measuring locations of the cross-section of wire rod are defined as the following. Four measuring locations, which are designated as O1, O2, O3 and O4, are equally spaced in the circle being D/4 away from the centre o
39、f wire rod (mid-radius, as shown in Figure 1).DD/O443OO1O2Figure 1 The schematic diagram of measuring locations7.2.2 Determination of measuring fields of viewOn each measuring locations Oi (i = 1, 2, 3 and 4), three continuous fields of view are taken to measure the percentage of resolvable pearlite
40、 and recorded as Si1, Si2, Si3. ISO 2015 All rights reserved 3BS ISO 16574:2015ISO 16574:2015(E)7.3 Measuring methods7.3.1 Manual point count methodAt each measuring location Oi (i=1, 2, 3 and 4) (see Figure 1), at least three continuous fields of view are taken to measure the percentage of resolvab
41、le pearlite in accordance with ISO 9042 and recorded as Si1, Si2, Si3. The percentage of resolvable pearlite of the whole cross-section of the wire rod, ,S is the average value of total 12 individual measurements.7.3.2 Automatic image analysis methodAt each measuring location Oi (see Figure 1), at l
42、east three continuous fields of view are taken. The metallographic microstructure photos have to be clearly shown on the image analyser. The brightness has to be adjusted in order to covering all the measured phase. The measurements are made on each field of view selected. Si1, Si2 and Si3 are obtai
43、ned from the first three fields of view, respectively. The percentage of resolvable pearlite of the whole cross-section of the wire rod, ,S is the average value of total 12 individual measurements.7.4 Reporting of resultsThe report shall include at least the following information unless otherwise ag
44、reed by the parties concerned:a) the steel grade examined, heat number, rod diameter, test locations and number;b) the magnification, numerical aperture, type of light and etchant used;c) the measuring method used;d) the result of the test (the average percentage of resolvable pearlite examined and
45、the standard deviation).4 ISO 2015 All rights reservedBS ISO 16574:2015ISO 16574:2015(E)Bibliography1 GB 13298, Metal-Inspection method of microstructure2 ASTM E3, Standard guide for preparation of metallographic specimens3 ASTM E407, Standard practice for microetching metals and alloys4 Vander Voor
46、t G.F. etc., Measurement of interlamellar spacing of pearlite. Metallography. 1984, 17 pp. 117 ISO 2015 All rights reserved 5BS ISO 16574:2015ISO 16574:2015(E) ISO 2015 All rights reservedICS 77.040.99Price based on 5 pagesThis page deliberately left blankBSI is the national body responsible for pre
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