1、Designation:A920/A920M14Standard Specification forSteel Bars,Microalloy,Hot-Wrought,Special Quality,Mechanical Properties1This standard is issued under the fixed designation A920/A920M;the number immediately following the designation indicates the yearof original adoption or,in the case of revision,
2、the year of last revision.A number in parentheses indicates the year of last reapproval.A superscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This specification covers hot-wrought,special qualitymicroalloyed carbon steel bars intended for use in applic
3、ationswhere as-rolled mechanical properties are desired.A typicalend use is hydraulic cylinder shafts.1.2 The bars shall be furnished to chemical composition andmechanical properties as provided herein.Chemical composi-tion is based on standard carbon steel grades modified toinclude microalloying el
4、ements such as columbium(niobium),vanadium,or molybdenum.Three strength classes areavailable,designated 75 520,80 550,and 100 690,corresponding to the minimum yield strength in ksi.1.3 Sections and sizes of bar steels available are covered inSpecification A29/A29M.1.4 Supplementary Requirements S1 t
5、o S5 are provided foruse when additional controls or requirements are desired.These shall apply only when specified on the purchase order.1.5 The values stated in either SI units or inch-pound unitsare to be regarded separately as standard.Within the text andtables,SI units are shown in brackets.The
6、 values stated in eachsystem may not be exact equivalents;therefore,each systemshall be used independently of the other.Combining valuesfrom the two systems may result in non-conformance with thestandard.1.6 Unless the order specifies the applicable“M”specifica-tion designation,the material shall be
7、 furnished to the inch-pound units.2.Referenced Documents2.1 ASTM Standards:2A29/A29M Specification for General Requirements for SteelBars,Carbon and Alloy,Hot-WroughtA370 Test Methods and Definitions for Mechanical Testingof Steel ProductsA576 Specification for Steel Bars,Carbon,Hot-Wrought,Special
8、 QualityE45 Test Methods for Determining the Inclusion Content ofSteel3.Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 microalloyed steels,ncarbon steels to which smallquantities of certain elements are added in order to enhancemechanical properties.3.1.1.1 DiscussionThis enhanc
9、ement of mechanical prop-erties results from control of the temperature and cooling rateduring the hot-rolling process.4.Ordering Information4.1 Orders for material supplied to this specification shouldinclude the following,as required,to describe adequately thedesired material:4.1.1 Quantity(weight
10、 or number of bars),4.1.2 Name of material(hot-rolled microalloyed steel bars),4.1.3 Dimensions,4.1.4 ASTM specification number and date of issue,4.1.5 Grade designation or chemical composition limits(seeSection 7),4.1.6 Class,4.1.7 Additions to the specification and SupplementaryRequirements,if req
11、uired,and,4.1.8 End use.5.General Requirements5.1 Material furnished under this specification shall con-form to the applicable requirements of the current edition ofSpecification A29/A29M,unless otherwise provided herein.6.Materials and Manufacture6.1 Melting PracticeThe steel shall be produced in a
12、ccor-dance with the applicable methods for primary and secondarymelting outlined in Specification A576.1This specification is under the jurisdiction of ASTM Committee A01 on Steel,Stainless Steel and Related Alloys and is the direct responsibility of SubcommitteeA01.15 on Bars.Current edition approv
13、ed Oct.1,2014.Published October 2014.Originallyapproved in 1993.Last previous edition approved in 2007 as A920/A920M 07.DOI:10.1520/A0920_A0920M-14.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards v
14、olume information,refer to the standards Document Summary page onthe ASTM website.*A Summary of Changes section appears at the end of this standardCopyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 6.2 The steel shall be killed.Supplementary
15、 RequirementsS1 through S5 may be invoked upon agreement betweenproducer and purchaser.6.3 The bars shall be special quality.6.4 The bars shall be hot-wrought,as wrought,unlessotherwise specified.7.Chemical Composition7.1 Typical examples of chemical compositions are shownin Table 1.Other compositio
16、ns may be specified using one ofthe following methods:7.1.1 Base compositions selected from Table 1 of Specifi-cation A576,with the addition of microalloying elements asprovided in 7.3 to 7.5,or7.1.2 Base compositions using the ranges and limits shownin Table 2 of Specification A576,with the addition of microal-loying elements as provided in 7.3 to 7.5.NOTE1For improved machinability,alternative sulfur ranges may bespecified upon agreement between the purchaser and the producer.Additional machin
