1、Designation:A911/A911M15Standard Specification forLow-Relaxation Steel Bars for Prestressed ConcreteRailroad Ties1This standard is issued under the fixed designation A911/A911M;the number immediately following the designation indicates the yearof original adoption or,in the case of revision,the year
2、 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.Scope*1.1 This specification covers low-relaxation steel bars foruse in prestressed concrete railroad ties.1.2 This specificati
3、on is applicable for orders in eitherinch-pounds units(as Specification A911)or in SI units(asSpecification A911M).1.3 The values stated in either inch-pound units or SI unitsare to be regarded separately as standard.Within the text,theSI units are shown in brackets.The values stated in eachsystem m
4、ay not be exact equivalents;therefore,each systemshall be used independently of the other.Combining valuesfrom the two systems may result in non-conformance with thespecification.2.Referenced Documents2.1 ASTM Standards:2A370 Test Methods and Definitions for Mechanical Testingof Steel ProductsE328 T
5、est Methods for Stress Relaxation for Materials andStructures2.2 Federal Standard:3Fed.Std.No.123 Marking for Shipments(Civil Agencies)2.3 Military Standards:3MIL-STD-129 Marking for Shipment and Storage3.Terminology3.1 Definition of Term Specific to This Specification:3.1.1 lot,nall the coils of ba
6、rs of the same nominal barsize contained on an individual shipping release or shippingorder,from the same heat of steel.4.Ordering Information4.1 Orders for low-relaxation steel bars for prestressedconcrete railroad ties under this specification shall contain thefollowing information:4.1.1 Quantity(
7、weight)mass,4.1.2 Nominal diameter of bar(inches)millimetres,4.1.3 Core diameter and length of coils(15.1),4.1.4 Packaging,4.1.5 Supplementary Requirement S1(if desired),and4.1.6 ASTM designation(A911 A911M)and year ofissue.4.2 The purchaser shall have the option to specify additionalrequirements,in
8、cluding but not limited to,the following:4.2.1 Prior relaxation tests of similarly-dimensioned bars(7.6.3),4.2.2 Inspection and witnessing of testing(Section 12),4.2.3 Load-elongation curves for each test(14.2),4.2.4 Special packaging and marking(Section 15),and4.2.5 Other special requirements,if an
9、y.5.Manufacture5.1 The bars shall be made from properly identified heats ofsteel made by the electric-furnace,the basic-oxygen,or othercommercially accepted steelmaking process.5.2 After hot-rolling,the bars shall be cold-drawn andfinally stress-relieved by induction heat treatment to producethe des
10、ired mechanical properties and then coiled.6.Chemical Requirements6.1 An analysis of each heat of steel shall be made by themanufacturer from test samples taken during the pouring ofeach heat.6.2 The analysis of the steel shall conform to the chemicalrequirements specified in Table 1.7.Mechanical Pr
11、operty Requirements7.1 Test MethodTests shall be made in accordance withTest Methods and Definitions A370,including Annex A4,using full-size bar specimens taken from either end of the coilof the finished product.1This specification is under the jurisdiction of ASTM Committee A01 on Steel,Stainless S
12、teel and Related Alloys and is the direct responsibility of SubcommitteeA01.05 on Steel Reinforcement.Current edition approved Nov.1,2015.Published January 2016.Originallypublished in 1992.Last previous edition approved in 2011 as A911/A911M 11.DOI:10.1520/A0911_A0911M-15.2For referenced ASTM standa
13、rds,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 Standardization Documents Order Desk,DODSSP,Bldg.4,SectionD,700RobbinsAve.,Ph
14、iladelphia,PA19111-5098,http:/dodssp.daps.dla.mil.*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 7.2 Tensile StrengthThe minimum tensile strength of thefinished bar,as repr
15、esented by test specimens,shall conform tothe requirements prescribed in Table 2.7.3 Yield StrengthYield strength shall be measured at 1%extension under load.The load at this extension is recorded asyield strength and shall meet the requirements of Table 2.7.4 ElongationThe total elongation after ru
16、pture shall notbe less than 6.0%and shall be measured in a gage length of4 in.100 mm.7.5 Wrapping TestBars shall withstand being woundaround a mandrel with a diameter of five times the bar diameterwithout cracking or other surface defects occurring on theoutside of the bent portion.The bar shall be bent around themandrel 1-12turns beginning with a 90 bend.7.6 Low-Relaxation TextBars shall be tested as prescribedin Test Methods E328.7.6.1 Low-relaxation bars shall meet the mechanical prop-erty re
