1、Designation: A 892 06Standard Guide forDefining and Rating the Microstructure of High CarbonBearing Steels1This standard is issued under the fixed designation A 892; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last
2、revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) 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
3、 rating 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
4、-tion 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 es
5、tablish 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 SpecimensE 407 Practice for Microetching Metals and AlloysE 1245 Practice for Determining the
6、 Inclusion or Second-Phase Constituent Content of Metals by Automatic ImageAnalysis3. Apparatus3.1 In order to adequately compare the structure of aspecimen with the photomicrographs, it will be necessary toview a properly prepared sample at 10003 magnification withgood resolution.4. Specimen Prepar
7、ation4.1 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 and the producer. It may be a full cross section butshould not be too large for practical handling in t
8、he 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 describedin Practice E 407. Nital (2 %) will frequently be an adequateetchant for routine examination. When crit
9、ical or detailedanalysis of structures is required, the recommended etchant isPicral (saturated).5. Description5.1 The reference photomicrographs are arranged into threecategories, as follows: carbide size (CS), carbide network(CN), and lamellar content (LC).5.2 Six photomicrographs for each categor
10、y are providedand are identified by category and number, for example,CS1-CS6, CN1-CN6, and LC1-LC6 as shown in Figs. 1-3.Higher numbers indicate a larger number or greater degree ofseverity of the category being rated.5.2.1 Actual counted number of carbides per 400 m2determined from the carbide size
11、 series of photomicrographs isas follows (reported counts are the average of three measure-ments):CS1 508CS2 419CS3 324CS4 234CS5 165CS6 1156. Procedure for Evaluation6.1 Using an optical metallograph and a magnification of10003, examine a properly prepared and etched specimen.Select a field which i
12、s 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 that1This guide is under the jurisdiction of Committee A01 on Steel, Stainless Steeland Related Alloys and is the direct responsibility of Sub
13、committee A01.28 onBearing Steels.Current edition approved Sept. 1, 2006. Published September 2006. Originallyapproved in 1988. Last previous edition approved in 2001 as A 892 88 (2001).2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceas
14、tm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.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 S
15、tates.most closely resembles the appearance of the specimen. 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
16、in accordancewith Practice E 1245. The rating shall be defined by thefollowing equation:FIG. 1 Carbide SizeA892062Rating 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 s
17、teel; chromium alloysteel; metallographyFIG. 2 Carbide NetworkA892063FIG. 3 Lamellar ContentA892064SUMMARY OF CHANGESCommittee A01 has identified the location of selected changes to this standard since the last issue (A 892 88(2001) that may impact the use of this standard. (Approved Sept. 1, 2006.)
18、(1) Practice E 1245 was added to the Referenced Documentssection.(2) Rating of carbide size by automatic image analysis wasadded as an alternate method.ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Us
19、ers 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 by the responsible technical committee and must be reviewed ever
20、y 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 receive careful consideration at a meeting of theresponsible techni
21、cal 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 International, 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).A892065
