1、Designation:A779/A779M16Standard Specification forSteel Strand,Seven-Wire,Uncoated,Compacted forPrestressed Concrete1This standard is issued under the fixed designation A779/A779M;the number immediately following the designation indicates the yearof original adoption or,in the case of revision,the y
2、ear 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 two types and three grades ofcompacted,seven-wire,uncoated strand for use in prestressed
3、concrete construction.The two types of strand are low-relaxation and stress-relieved(normal-relaxation).The threegrades are 245 1700,260 1800 and 270 1860.1.2 This specification is applicable for orders in eitherinch-pound units(as Specification A779)or in SI units(asSpecification A779M).1.3 The val
4、ues stated in either inch-pound or SI units are tobe regarded as standard.Within the text,the SI units are shownin brackets.The values stated in each system may not be exactequivalents;therefore,each system shall be used independentlyof the other.Combining values from the two systems mayresult in no
5、n-conformance with the specification.2.Referenced Documents2.1 ASTM Standards:2A751 Test Methods,Practices,and Terminology for Chemi-cal Analysis of Steel ProductsA994 Guide for Editorial Procedures and Form of ProductSpecifications for Steel,Stainless Steel,and RelatedAlloysA1061/A1061M Test Method
6、s for Testing Multi-Wire SteelPrestressing Strand2.2 U.S.Military Standard3MIL-STD-129 Marking for Shipment and Storage2.3 U.S.Federal Standard3Fed.Std.No.123 Marking for Shipments(Civil Agencies)3.Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 compacted strandstrand that has be
7、en compacted bydrawing through a die or a similar compacting process andsubsequently stress-relieved prior to winding into reels orreelless packs.3.1.2 lotall of the compacted strand of the same grade inthe reels or reelless packs produced on the same productionequipment and submitted for inspection
8、 at the same time.3.1.3 stranda group of wires having a center wire en-closed tightly by six helically placed outer wires with auniform pitch of not less than 14 and not more than 18 timesthe nominal diameter of the strand.4.Classification4.1 Grade 245 1700Nominal diameter of 0.7 in.18.0mm with tens
9、ile strength of 247 ksi 1705 MPa based onnominal area of the strand.4.2 Grade 260 1800Nominal diameter of 0.6 in.15.2mm with tensile strength of 263 ksi 1815 MPa based onnominal area of the strand.4.3 Grade 270 1860Nominal diameter of 0.5 in.12.7mm with tensile strength of 270 ksi 1860 MPa based onn
10、ominal area of the strand.5.Ordering Information5.1 It shall be the responsibility of the purchaser to specifyall requirements that are necessary for material ordered to thisspecification.Such requirements to be considered include,butare not limited to,the following:5.1.1 Quantity(feet metres),5.1.2
11、 Type of strand(low-relaxation or stress-relieved(normal-relaxation),5.1.3 Grade and nominal diameter of strand(Section 4),5.1.4 Load-elongation curve,if desired(12.2.1),5.1.5 Outside inspection,if required(Section 13),5.1.6 Packaging(16.1),and5.1.7 ASTM designation and date of issue.1This specifica
12、tion is under the jurisdiction of ASTM Committee A01 on Steel,Stainless Steel and Related Alloys and is the direct responsibility of SubcommitteeA01.05 on Steel Reinforcement.Current edition approved Sept.1,2016.Published September 2016.Originallyapproved in 1980.Last previous edition approved in 20
13、12 as A779/A779M 12.DOI:10.1520/A0779_A0779M-16.2For referenced ASTM standards,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 St
14、andardization Documents Order Desk,DODSSP,Bldg.4,SectionD,700RobbinsAve.,Philadelphia,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
15、6.Materials and Manufacture6.1 The steel shall be of such quality that,when processed,the finished wire shall be free of detrimental flaws and unduesegregation.6.2 Wire from which the strand is to be fabricated shall bein the cold-drawn condition and have a common dry-drawnfinish.6.3 After stranding
16、 and compacting,all low-relaxationstrand shall be subjected to a continuous thermal-mechanicaltreatment to produce the prescribed mechanical properties.Forstress-relieved(normal-relaxation)strand,only thermal treat-ment is necessary.Temper colors which result from thestress-relieving operation are considered normal for the fin-ished appearance of this strand.7.Chemical Requirements7.1 The chemical analysis of each heat shall be determinedin accordance with Test Methods,Practices,and TerminologyA
