1、Designation: A892 09Standard Guide forDefining and Rating the Microstructure of High CarbonBearing Steels1This standard is issued under the fixed designation A892; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last re
2、vision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This guide covers the description of carbide structures inannealed high carbon bearing steels.1.2 Included is a guide for ra
3、ting steel specimens by agraded series of photomicrographs showing the incidence ofcertain conditions.1.3 The reference photomicrographs are graded illustrationsof annealed carbides categorized by size, network, and lamellarcontent (shape).1.4 This guide is to facilitate communication and descrip-ti
4、on of microstructure. It does not establish limits of accept-ability. Such limits are a matter of agreement between user andproducer.1.5 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to estab
5、lish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2E3 Guide for Preparation of Metallographic SpecimensE407 Practice for Microetching Metals and AlloysE1245 Practice for Determining the Incl
6、usion or Second-Phase Constituent Content of Metals by Automatic ImageAnalysis2.2 ASTM Adjuncts:Photomicrographs for Defining and Rating the Microstruc-ture of High Carbon Bearing Steels33. Apparatus3.1 In order to adequately compare the structure of aspecimen with the photomicrographs, it will be n
7、ecessary toview a properly prepared sample at 10003 magnification withgood resolution.4. Specimen Preparation4.1 Samples that represent a portion of the cross section ofthe material shall be prepared using the practices described inGuide E3. The size of the sample shall be negotiated betweenthe user
8、 and the producer. It may be a full cross section butshould not be too large for practical handling in the polishingoperation.4.2 The properly polished specimens shall be etched in asuitable etchant which will clearly delineate the annealedcarbide structure of the material being examined as describe
9、din Practice E407. Nital (2 %) will frequently be an adequateetchant for routine examination. When critical or detailedanalysis of structures is required, the recommended etchant isPicral (saturated).5. Description5.1 The reference photomicrographs (available in ASTMAdjunct ADJA08923) are arranged i
10、nto three categories, asfollows: carbide size (CS), carbide network (CN), and lamellarcontent (LC).5.2 Six photomicrographs for each category are providedand are identified by category and number, for example,CS1-CS6, CN1-CN6, and LC1-LC6. Higher numbers indicatea larger number or greater degree of
11、severity of the categorybeing rated.5.2.1 Actual counted number of carbides per 400 m2determined from the carbide size series of photomicrographs isas follows (reported counts are the average of three measure-ments):CS1 508CS2 419CS3 3241This guide is under the jurisdiction of Committee A01 on Steel
12、, Stainless Steeland Related Alloys and is the direct responsibility of Subcommittee A01.28 onBearing Steels.Current edition approved Oct. 1, 2009. Published January 2010. Originallyapproved in 1988. Last previous edition approved in 2006 as A892 06. DOI:10.1520/A0892-09.2For referenced ASTM standar
13、ds, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from ASTM International Headquarters. Order Adjunct No.ADJA0892. Original adju
14、nct produced in 2009.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.CS4 234CS5 165CS6 1156. Procedure for Evaluation6.1 Using an optical metallograph and a magnificat
15、ion of10003, examine a properly prepared and etched specimen.Select a field which is representative of the category to begraded and compare it to the photomicrographs which are partof this method. The rating will be the number of that photo thatmost closely resembles the appearance of the specimen.
16、Aseparate field may be used for each category or a single fieldmay be rated for more than one category. An example rating isCS4, CN2, LC1.6.2 As an alternate method, the rating of carbide size byautomatic image analysis shall be conducted in accordancewith Practice E1245. The rating shall be defined
17、 by thefollowing equation:Rating 5 6.7888 4.5924 106! * nA(1)where nA= number of carbides per mm2.The results shall be rounded to the nearest integer value from1to6.7. Keywords7.1 antifriction bearings; bearing steel; chromium alloysteel; metallographySUMMARY OF CHANGESCommittee A01 has identified t
18、he location of selected changes to this standard since the last issue (A892-06)that may impact the use of this standard. (Approved Oct. 1, 2009.)(1) The reference photomicrographs were moved to ASTMAdjunct ADJA0892.ASTM International takes no position respecting the validity of any patent rights ass
19、erted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time b
20、y the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will rece
21、ive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM Inte
22、rnational, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org). Permission rights to photocopy the standard may also be secured from the ASTM website (www.astm.org/COPYRIGHT/).A892 092
