1、Designation: A421/A421M 15 American Association StateHighway and Transportation Officials StandardAASHTO No.: M 204Standard Specification forStress-Relieved Steel Wire for Prestressed Concrete1This standard is issued under the fixed designation A421/A421M; the number immediately following the design
2、ation indicates the yearof original adoption or, in the case of revision, 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.This standard has been approved for use by a
3、gencies of the U.S. Department of Defense.1. Scope*1.1 This specification covers two types of stress-relievedround high-carbon steel wire commonly used in prestressedconcrete construction, as follows:1.1.1 Type BA wire is used for applications in whichcold-end deformation is used for anchoring purpo
4、ses (ButtonAnchorage), and1.1.2 Type WA wire is used for application in which the endsare anchored by wedges, and no cold-end deformation of thewire is involved (Wedge Anchorage).1.2 A supplementary requirement (S1) is provided for usewhere low-relaxation wire and relaxation testing for thatproduct
5、is required by the purchaser. The supplementaryrequirement applies only when specified in the purchase order.1.3 This specification is applicable for orders in eitherinch-pounds units (as Specification A421) or in SI units (asSpecification A421M).1.4 The values stated in either inch-pound or SI unit
6、s are tobe regarded separately as standard. Within the text, the SI unitsare shown in brackets. The values stated in each system maynot be exact equivalents; therefore, each system shall be usedindependently of the other. Combining values from the twosystems may result in non-conformance with the sp
7、ecification.2. Referenced Documents2.1 ASTM Standards:2A370 Test Methods and Definitions for Mechanical Testingof Steel ProductsA751 Test Methods, Practices, and Terminology for Chemi-cal Analysis of Steel ProductsE328 Test Methods for Stress Relaxation for Materials andStructures2.2 Military Standa
8、rd:3MIL-STD-129 Marking for Shipment and Storage2.3 Federal Standard:3Fed. Std. No. 123 Marking for Shipments (Civil Agencies)3. Ordering Information3.1 It shall be the responsibility of the purchaser to specifyall requirements that are necessary for material ordered to thisspecification. Such requi
9、rements shall include, but are notlimited to, the following:3.1.1 Quantity lb kg,3.1.2 Nominal diameter,3.1.3 Name of material (uncoated stress-relieved steel wirefor prestressed concrete, Type BA or WA wire),3.1.4 If outside inspection is required (10.1),3.1.5 Packaging,3.1.6 Supplementary Requirem
10、ent S1 (if desired), and3.1.7 ASTM designation and date of issue.4. Manufacture4.1 ProcessThe steel shall be made by any commerciallyaccepted process.4.2 Internal SoundnessA sufficient discard shall be madeto ensure freedom from injurious piping and undue segrega-tion.4.3 WireThe wire shall be cold-
11、drawn to size and suitablystress-relieved after cold drawing by a continuous heat treat-ment to produce the prescribed mechanical properties.5. Mechanical Property Requirements5.1 Tensile StrengthThe tensile strength of Type BA wireand Type WA wire shall conform to the requirements pre-scribed in Ta
12、ble 1, and shall be determined as prescribed inTest Methods and Definitions A370, including Annex A4.1This specification 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 e
13、dition approved Nov. 1, 2015. Published November 2015. Originallyapproved in 1958. Last previous edition approved in 2010 as A421/A421M 10.DOI: 10.1520/A0421_A0421M-15.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual
14、 Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from Standardization Documents Order Desk, DODSSP, Bldg. 4,Section D, 700 Robbins Ave., Philadelphia, PA 19111-5098, http:/dodssp.daps.dla.mil.*A Summary of Changes section appears a
15、t the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States15.2 Yield Strength:5.2.1 The minimum yield strength for all wire, measured bythe 1.0 % extension under load method, shall not be less than85 % of the specified
16、minimum tensile strength.5.2.2 The extension under load shall be measured by anextensometer calibrated with the smallest division not largerthan 0.0001 in./in. 0.0001 mm/mm of gage length.5.2.3 The initial load corresponding to the initial stressprescribed in Table 2 shall be applied to the specimen
17、, at whichtime the extensometer is attached and adjusted to a reading of0.001 in./in. 0.001 mm/mm of gage length. The load shallthen be increased until the extensometer indicates an extensionof 1 %. The load for this extension shall be recorded. The stresscorresponding to this load shall meet the re
18、quirements forstress at 1 % extension prescribed in Table 2.5.3 ElongationThe total elongation under load of all wireshall not be less than 4.0 % when measured in a gage length of10 in. 250 mm. The elongation shall be determined by anextensometer which is placed on the test specimen after a loadcorr
19、esponding to the initial stress prescribed in Table 2 isapplied. If the fracture takes place outside of the gage lengthand the elongation so measured meets the minimumrequirements, no further testing shall be required. If theelongation is less than the minimum requirements, the test shallbe consider
20、ed an invalid test and a retest made.6. Diameter and Permissible Variations6.1 Wire meeting the requirements of this specification isnormally ordered in the nominal diameters shown in Table 1.6.2 The diameter of the wire shall not vary from the nominaldiameter specified by more than 60.002 in. 60.05
21、 mm.6.3 The wire shall not be out-of-round by more than 0.002in. 0.05 mm.7. Workmanship and Finish7.1 CastA wire sample having a chord length of 60 in.1500 mm shall have an offset at the center of the chord of notmore than 3 in. 75 mm. This is equivalent to a chord of an arcof a circle not less than
22、 25 ft 7.6 m in diameter.7.2 Type BA WireType BAwire shall be of suitable qualityto permit cold forming of button heads for anchorage. Splittingshall not be considered a cause for rejection if the buttonanchorage is capable of developing the minimum requiredtensile strength of the wire.7.3 The wire
23、shall be free of kinks.7.4 The wire shall be furnished in firmly tied coils having aminimum inside diameter of 48 in. 1200 mm. Each coil shallbe of one continuous length.7.5 There shall be no welds or joints in the finished wire.Any welds or joints made during manufacture to enablecontinuity of oper
24、ations shall be removed.7.6 The wire shall not be oiled or greased. Slight rusting,provided it is not sufficient to cause pits visible to a person withnormal or corrected vision, shall not be cause for rejection.7.7 Temper colors which result from the stress-relievingoperation are considered normal
25、for the finished appearance ofthis wire.8. Chemical Requirements8.1 Variations in manufacturing processes and equipmentamong wire manufacturers necessitate the individual selectionof an appropriate chemical composition at the discretion of themanufacturer.8.2 Phosphorus and sulfur values shall not e
26、xceed thefollowing:PhosphorusSulfur0.040 %0.050 %8.3 The purchaser shall have the right to make an analysisfrom finished wire representing each heat of steel. Samples foranalysis shall be obtained by milling the wire in such a manneras to obtain a sample representative of the entire cross section.Pr
27、ior to milling, the surface shall be cleaned to remove allforeign matter. All such individual determinations shall notvary from the limits shown in 8.2 by more than 0.008 %.8.4 For referee purposes, Test Methods, Practices, andTerminology A751 shall be applied.9. Sampling9.1 Unless otherwise agreed
28、upon between the manufacturerand the purchaser, one test specimen shall be taken from each10 coils or less in a lot (Note 1) and tested to determinecompliance with 5.1, 5.2, 5.3, 6, and 7.1.NOTE 1The term “lot” means all the coils of wire of the same nominalwire size contained in an individual shipp
29、ing release or shipping order.10. Inspection10.1 The purchaser shall state at the time of order whetheroutside inspection is required. If outside inspection is required,the manufacturer shall afford the inspector representing thepurchaser all reasonable facilities to satisfy the inspector thatthe ma
30、terial is being furnished in accordance with this speci-fication. All tests and inspections shall be made at the place ofTABLE 1 Tensile Strength RequirementsNominalDiameter,in. mmTensile Strength, min, psi MPaType BA Type WA0.192 4.88A250 000 17250.196 4.98 240 000 1655 250 000 17250.250 6.35 240 0
31、00 1655 240 000 16550.276 7.01 235 000 1620 235 000 1620AThis size is not commonly furnished in Type BA wire.TABLE 2 Yield Strength RequirementsNominalDiameter,in. mmInitial Stress,psi MPaMinimum Stress at 1 %Extension, psi MPaType BA Type WA0.192 4.88 29 000 200A212 500 14650.196 4.98 29 000 200 20
32、4 000 1407 212 500 14650.250 6.35 29 000 200 204 000 1407 204 000 14070.276 7.01 29 000 200 199 750 1377 199 750 1377AThis size is not commonly furnished in Type BA wire.A421/A421M 152manufacture prior to shipment, unless otherwise agreed upon atthe time of purchase, and shall be so conducted withou
33、tunnecessarily interfering with manufacturing operations.11. Rejection11.1 Unless otherwise specified, any rejection based on testsmade in accordance with this specification shall be reported tothe manufacturer within a reasonable length of time.12. Certification12.1 If outside inspection is not req
34、uired, a manufacturerscertification that the material has been tested in accordancewith and meets the requirements of this specification shall bethe basis of acceptance of the material.12.2 A Material Test Report, Certificate of Inspection, orsimilar document printed from or used in electronic form
35、froman electronic data interchange (EDI) transmission shall beregarded as having the same validity as a counterpart printed inthe certifiers facility. The content of the EDI transmitteddocument shall meet the requirements of the invoked ASTMstandard(s) and conform to any existing EDI agreement be-tw
36、een the purchaser and the manufacturer. Notwithstanding theabsence of a signature, the organization submitting the EDItransmission is responsible for the content of the report.NOTE 2The industry definition as invoked here is: EDI is thecomputer-to-computer exchange of business information in a stand
37、ardformat such as ANSI ASC X12.13. Packaging and Package Marking13.1 The type of wire, size of the wire, ASTM designationA421 A421M, heat number, and name of the manufacturershall be marked on a tag securely attached to each coil of wire.13.2 When specified in the purchase order or contract, andfor
38、direct procurement by or direct shipment to the U.S.Government, marking for shipment shall be in accordance withFed. Std. No. 123 for civil agencies and MIL-STD-129 formilitary agencies.14. Keywords14.1 cold-drawn wire; low-relaxation wire; prestressed con-crete; steel wire (tendon); stress-relieved
39、 wireSUPPLEMENTARY REQUIREMENTSS1. LOW-RELAXATION WIRE AND RELAXATION TESTINGThe following supplementary requirement shall apply only when specified in the purchase order orcontract.S1.1 ScopeS1.1.1 This supplementary requirement delineates onlythose details which are peculiar to low-relaxation wire
40、, and tothe method of relaxation testing related to single wire tendonshaving properties generally as described in Specification A421/A421M.S1.2 Test MethodS1.2.1 Low-relaxation wire shall be tested as prescribed inTest Methods E328.S1.3 Relaxation PropertiesS1.3.1 Low-relaxation wire shall meet the
41、 mechanical prop-erty requirements of this specification, with the added require-ment that relaxation after 1000 h under the conditions ofSection S1.5 shall not be more than 2.5 % when initially loadedto 70 % of specified minimum tensile strength or not more than3.5 % when loaded to 80 % of specifie
42、d minimum tensilestrength of the wire.S1.4 Yield StrengthS1.4.1 Yield strength of low-relaxation wire as described in5.2 shall not be less than 90 % of the specified minimum tensilestrength of the wire.S1.5 Conditions of Relaxation TestS1.5.1 If required, relaxation evidence shall be providedfrom th
43、e manufacturers records of tests on similarly dimen-sioned wire of the same grade.S1.5.2 The temperature of the test specimen shall be main-tained at 68 6 3.5F 20 6 2C.S1.5.3 The test specimen shall not be subjected to anyloading prior to the relaxation test.S1.5.4 The initial load shall be applied
44、uniformly over aperiod of not less than 3 minutes and not more than 5 minutes,and the gage length shall be maintained constant; load relax-ation readings shall commence 1 minute after application of thetotal load.S1.5.5 Overstressing of the test specimen during the loadingoperation shall not be perm
45、itted.S1.5.6 The duration of the test shall be 1000 h or a shorterperiod extrapolated to 1000 h which can be shown by recordsto provide similar relaxation values.S1.5.7 The test gage length shall be at least 60 times thenominal diameter.A421/A421M 153SUMMARY OF CHANGESCommittee A01 has identified th
46、e location of selected changes to this standard since the last issue(A421/A421M 10) that may impact the use of this standard. (Approved Nov. 1, 2015.)(1) Revised the specifications title. (2) Revised 1.1, 1.4, 4.1, 12.2, 13.1, and 13.2.ASTM International takes no position respecting the validity of
47、any patent rights asserted 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 r
48、evision at any time by 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. Yo
49、ur comments will receive 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 International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard ma
