BS PD ISO TR 945-3-2016 Microstructure of cast irons Matrix structures《铸铁的微观结构 矩阵结构》.pdf

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1、Microstructure of cast irons Part 3: Matrix structures PD ISO/TR 945-3:2016 BSI Standards Publication WB11885_BSI_StandardCovs_2013_AW.indd 1 15/05/2013 15:06National foreword This Published Document is the UK implementation of ISO/TR 945-3:2016. The UK participation in its preparation was entrusted

2、 to Technical Committee ISE/111, Steel Castings and Forgings. A list of organizations represented on this committee can be obtained on request to its secretary. This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application.

3、 The British Standards Institution 2016. Published by BSI Standards Limited 2016 ISBN 978 0 580 90577 3 ICS 77.080.10 Compliance with a British Standard cannot confer immunity from legal obligations. This Published Document was published under the authority of the Standards Policy and Strategy Commi

4、ttee on 31 May 2016. Amendments/corrigenda issued since publication Date Text affected PUBLISHED DOCUMENT PD ISO/TR 945-3:2016 ISO 2016 Microstructure of cast irons Part 3: Matrix structures Microstructure des fontes Partie 3: Structures de matrice TECHNICAL REPORT ISO/TR 945-3 Reference number ISO/

5、TR 945-3:2016(E) First edition 2016-05-01 PD ISO/TR 945-3:2016 ISO/TR 945-3:2016(E)ii ISO 2016 All rights reserved COPYRIGHT PROTECTED DOCUMENT ISO 2016, Published in Switzerland All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in a

6、ny 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 copyright office Ch. de Bl

7、andonnet 8 CP 401 CH-1214 Vernier, Geneva, Switzerland Tel. +41 22 749 01 11 Fax +41 22 749 09 47 copyrightiso.org www.iso.org PD ISO/TR 945-3:2016 ISO/TR 945-3:2016(E)Foreword iv Introduction v 1 Scope . 1 2 Designations and descriptions of cast iron microstructures . 1 2.1 Ferrite . 1 2.2 Pearlite

8、 . 1 2.3 Austenite 2 2.4 Acicular ferrite 2 2.5 Ausferrite . 2 2.6 Bainite . 2 2.7 Cementite . 2 2.8 Ledeburite . 2 2.9 Martensite . 2 3 Sampling and preparation of samples . 3 3.1 Samples taken from castings and cast samples 3 3.2 Sample preparation 3 4 Matrix structures . 4 4.1 Grey cast irons . 4

9、 4.2 Spheroidal graphite cast irons . 6 4.3 Austenitic cast irons .10 4.4 Malleable cast irons 11 4.5 Compacted (vermicular) graphite cast irons 23 4.6 Ausferritic spheroidal graphite cast irons 24 4.7 Abrasion-resistant cast irons .26 Annex A (informative) Spheroidal graphite cast irons: Evaluation

10、 of pearlite content .32 Annex B (informative) List of European and some national cast iron material designations corresponding to the ISO designations 34 Bibliography .42 ISO 2016 All rights reserved iii Contents Page PD ISO/TR 945-3:2016 ISO/TR 945-3:2016(E) Foreword ISO (the International Organiz

11、ation for Standardization) is a worldwide 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

12、 has the right to be represented on that 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. T

13、he procedures used to develop this document 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

14、editorial rules of the ISO/IEC Directives, 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

15、 rights identified during the development 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 a

16、n explanation on the meaning of ISO specific 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 information The committee responsible for th

17、is document is ISO/TC 25, Cast irons and pig irons. ISO 945 consists of the following parts, under the general title Microstructure of cast irons: Part 1: Graphite classification by visual analysis Part 2: Graphite classification by image analysis Technical Report Part 3: Matrix structures Technical

18、 Report The following parts are under preparation: Part 4: Determination of nodularity in spheroidal graphite cast ironsiv ISO 2016 All rights reserved PD ISO/TR 945-3:2016 ISO/TR 945-3:2016(E) Introduction The designation of cast iron matrix structures as given in this part of ISO 945 is in conform

19、ity with the designations published by several national foundry organisations 123or other publishers 4 . This Technical Report aims to give the designations, precise descriptions and reference micrographs of the matrix structures of cast irons, and facilitate the discussion and to avoid misunderstan

20、ding between manufacturer and purchaser regarding the identification of matrix structures. ISO 2016 All rights reserved v PD ISO/TR 945-3:2016 Microstructure of cast irons Part 3: Matrix structures 1 Scope This Technical Report gives the designations, descriptions and reference micrographs of the ma

21、trix structures of cast irons. It applies to the following types of cast irons: grey cast irons (Table 4.1); spheroidal graphite cast irons (Table 4.2); austenitic cast irons (Table 4.3); malleable cast irons (Table 4.4); compacted (vermicular) graphite cast irons (Table 4.5); ausferritic spheroidal

22、 graphite cast irons (Table 4.6); abrasion-resistant cast irons (Table 4.7). Each matrix structure is defined with explanations and micrographs. Unless otherwise stated in Clause 4, the micrographs shown correspond to samples etched with a solution of 2 % nitric acid in ethanol (Nital). 2 Designatio

23、ns and descriptions of cast iron microstructures 2.1 Ferrite Ferrite also known as -ferrite (-Fe) or alpha iron is a materials science term for iron, or for a solid solution with iron as the main constituent, with a body-centred cubic crystal structure. It is this crystalline structure which gives t

24、o steels and cast irons their magnetic properties, and is the classic example of a ferromagnetic material. Since pearlite has ferrite as a component, any iron-carbon alloy will contain some amount of ferrite if it is allowed to reach equilibrium at room temperature. The exact amount of ferrite will

25、depend on the cooling processes the iron-carbon alloy undergoes when it cools from liquid state. 2.2 Pearlite Pearlite is a two-phased, lamellar (or layered) structure composed of alternating layers of alpha- ferrite (according thermal dynamical condition 88 % by mass) and cementite (12 % by mass).

26、The lamellar appearance is misleading since the individual lamellae within a colony are connected in three dimensions; a single colony is therefore an interpenetrating bicrystal of ferrite and cementite. Pearlite is a common microstructure occurring in many grades of cast irons. If cast iron is cool

27、ed very slowly or as a result of heat treatment, the cementite can occur in globules instead of in layers. This structure is designated as globular pearlite. TECHNICAL REPORT ISO/TR 945-3:2016(E) ISO 2016 All rights reserved 1 PD ISO/TR 945-3:2016 ISO/TR 945-3:2016(E) 2.3 Austenite Austenite, also k

28、nown as gamma phase iron (-Fe), is a non-magnetic allotrope of iron or a solid solution of iron, stabilized by an alloying element, e.g. nickel. Austenite is the face-centred cubic crystal structure of iron. 2.4 Acicular ferrite Acicular ferrite is a microstructure of ferrite that is characterized b

29、y needle shaped crystallites or grains when viewed in two dimensions. The grains, actually three dimensional in shape, have a thin lenticular shape. This microstructure is advantageous over other microstructures because of its chaotic ordering, which increases toughness. 2.5 Ausferrite Ausferrite is

30、 a special type of multi-phase microstructure that occurs when cast irons with a silicon content of about 2 % or higher are austempered. Austempering consists of rapidly cooling the fully austenitic iron to avoid the formation of pearlite to a temperature above that of martensite formation and holdi

31、ng for the time necessary to precipitate the ausferrite matrix. This microstructure consists primarily of acicular ferrite in carbon enriched austenite. 2.6 Bainite Bainite is a multi-phase microstructure, consisting of acicular ferrite and cementite that forms in cast irons during rapid cooling. It

32、 is one of the decomposition products that can form when austenite is cooled rapidly below the eutectoid temperature, but above the martensitic starting (M s ) temperature. Bainite can also form from the decomposition of ausferrite upon extended heating above the temperature at which it was formed.

33、2.7 Cementite Cementite, also known as iron carbide, is a compound of iron and carbon, with the formula Fe 3 C. By mass, it is 6,7 % carbon and 93,3 % iron. Cementite has an orthorhombic crystal structure. In the iron-carbon system cementite is a common constituent because ferrite contains maximum 0

34、,02 % by mass of carbon. Therefore, in cast irons that are slowly cooled, a part of these elements is in the form of cementite. In the case of white cast irons, cementite precipitates directly from the melt. In grey cast irons or spheroidal graphite cast irons, cementite forms either from austenite

35、during cooling or from martensite during tempering, or from the decomposition of ausferrite. An intimate mixture of cementite with ferrite, the other product of austenite, forms a lamellar structure called pearlite (see 2.2). 2.8 Ledeburite Ledeburite is an eutectic mixture of austenite and cementit

36、e and is formed when the melt at least partly solidifies according the metastable Fe-C-Si system. 2.9 Martensite Martensite is formed from austenite by rapid cooling (quenching) which traps carbon atoms that do not have time to diffuse out of the crystal structure. The martensite lattice is body-cen

37、tred tetragonal composed of ferrite and carbon. This martensitic reaction begins during cooling when the austenite reaches the martensite start temperature (M s ) and the parent austenite becomes mechanically unstable. At a constant temperature below M s , a fraction of the parent austenite transfor

38、ms rapidly, after which no further transformation occurs. When the temperature is decreased, more of the austenite transforms to martensite. Finally, when the martensite finish temperature (M f ) is reached, 2 ISO 2016 All rights reserved PD ISO/TR 945-3:2016 ISO/TR 945-3:2016(E) the transformation

39、ends. Martensite can also be formed by application of stress in ausferritic spheroidal graphite cast irons (SITRAM effect: stress induced transformation from austenite to martensite). Thus, martensite can be thermally induced or stress induced. 3 Sampling and preparation of samples 3.1 Samples taken

40、 from castings and cast samples The location from which samples are taken should be agreed between the manufacturer and purchaser and should take into account the requirements specified in the appropriate material standard. If an examination report is required, the location from where the final samp

41、le is taken shall be recorded. The sample should be of sufficient size to provide a true representation of the matrix structure in the agreed location from which it is taken. 3.2 Sample preparation Attention should be paid to the careful cutting, grinding, polishing and etching of samples, so that t

42、he matrix structure appears in its original form. Inappropriate preparation can cause alteration of the microstructure and misinterpretations. Sample preparation should be carried out in four stages: 1) sectioning; 2) grinding; 3) polishing; 4) etching. NOTE In some cases mounting of the sample in a

43、 polymeric material can be necessary. The examination of the matrix structure shall be carried out in the etched condition. ISO 2016 All rights reserved 3 PD ISO/TR 945-3:2016 ISO/TR 945-3:2016(E) 4 Matrix structures 4.1 Grey cast irons Table 4.1 Grey cast irons according to ISO 185 5 Micro- graph M

44、aterial designation Matrix structure 4.1.1 ISO 185/JL/100 ISO 185/JL/HBW155 Pearlite ferrite 100 x 4.1.2 ISO 185/JL/150 ISO 185/JL/HBW175 Pearlite ferrite 100 x 4.1.3 Pearlite ferrite 500 x4 ISO 2016 All rights reserved PD ISO/TR 945-3:2016 ISO/TR 945-3:2016(E) Micro- graph Material designation Matr

45、ix structure 4.1.4 ISO 185/JL/200 ISO 185/JL/225 ISO 185/JL/250 ISO 185/JL/275 ISO 185/JL/HBW195 ISO 185/JL/HBW215 Predominantly pearlite 100 x Shown is JL/250 4.1.5 Predominantly pearlite 500 x Shown is JL/250 4.1.6 ISO 185/JL/300 (shown) ISO 185/JL/350 ISO 185/JL/HBW235 ISO 185/JL/HBW255 Pearlite

46、100xTable 4.1 (continued) ISO 2016 All rights reserved 5 PD ISO/TR 945-3:2016 ISO/TR 945-3:2016(E) 4.2 Spheroidal graphite cast irons Table 4.2 Spheroidal graphite cast irons according to ISO 1083 6 Micro- graph Material designation Matrix structure 4.2.1 ISO 1083/JS/350-22 ISO 1083/JS/400-18 ISO 10

47、83/JS/400-15 ISO 1083/JS/500-10 ISO 1083/JS/HBW130 ISO 1083/JS/HBW150 ISO 1083/JS/HBW155 Ferrite 100x 4.2.2 ISO 1083/JS/450-10 ISO 1083/JS/HBW185 Predominantly aferrite 100x 4.2.3 ISO 1083/JS/500-7 ISO 1083/JS/550-5 ISO 1083/JS/HBW200 ISO 1083/JS/HBW215 Ferrite pearlite 100x aThe term “predominantly

48、” does not appear in ISO 1083, only “ferrite”. NOTE Information regarding the evaluation of the pearlite content of the matrix of spheroidal graphite cast iron is given in Annex A.6 ISO 2016 All rights reserved PD ISO/TR 945-3:2016 ISO/TR 945-3:2016(E) Micro- graph Material designation Matrix struct

49、ure 4.2.4 ISO 1083/JS/600-3 ISO 1083/JS/HBW230 Pearlite ferrite 100x 4.2.5 ISO 1083/JS/700-2 ISO 1083/JS/HBW265 Predominantly apearlite 100x 4.2.6 Pearlite 500x aThe term “predominantly” does not appear in ISO 1083, only “ferrite”. NOTE Information regarding the evaluation of the pearlite content of the matrix of spheroidal graphite cast iron is given in Annex A.Table 4.2 (continued) ISO 2016 All rights reserved 7 PD ISO/TR 945-3:2016 ISO/TR 945-3:2016(E) Micro- graph Mater