1、Designation: A 726 05Standard Specification forCold-Rolled Magnetic Lamination Quality Steel,Semiprocessed Types1This standard is issued under the fixed designation A 726; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of
2、 last 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. Scope1.1 This specification covers cold-rolled carbon sheet steelused for magnetic applications. These products, commonlycall
3、ed “cold-rolled magnetic lamination steel” (CRML) areusually intended for applications in which the stamped lami-nations or assembled core structures for electrical equipmentare annealed to develop the desired core loss and permeabilitycharacteristics.1.2 By using appropriate lamination annealing pr
4、actices, theuser can optimize magnetic properties for the various types.1.3 Non-guaranteed core-loss types, usually made to con-trolled chemical compositions, are available but are not cov-ered by this specification.1.4 Higher quality core-loss types are made to controlledchemical compositions and a
5、re usually given a critical reduc-tion on a temper-mill to yield specified magnetic propertiesafter a suitable lamination anneal. These products, typicallycalled semiprocessed lamination steel, are classified by theASTM Code Letter D in accordance with Practice A 664.1.5 The values stated in customa
6、ry (cgs-emu and inch-pound) units are to be regarded as standard. The values givenin parentheses are mathematical conversions to SI units whichare provided for information only and are not consideredstandard.2. Referenced Documents2.1 ASTM Standards:2A 340 Terminology of Symbols and Definitions Rela
7、ting toMagnetic TestingA 343/A 343M Test Method for Alternating-Current Mag-netic Properties of Materials at Power Frequencies UsingWattmeter-Ammeter-Voltmeter Method and 25-cm EpsteinTest FrameA 370 Test Methods and Definitions for Mechanical Testingof Steel ProductsA 664 Practice for Identificatio
8、n of Standard Electrical- andLamination-Steel Grades in ASTM SpecificationsA 700 Practices for Packaging, Marking, and LoadingMethods for Steel Products for Domestic ShipmentE18Test Methods for Rockwell Hardness and RockwellSuperficial Hardness of Metallic MaterialsE 140 Hardness Conversion Tables f
9、or Metals3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 cold-rolled sheetsheet manufactured from hot-rolled descaled coils by cold reducing to the desired thickness,generally followed by annealing to recrystallize the grainstructure. In the case of magnetic lamination steels,
10、 particularlysemiprocessed lamination steels, temper rolling is used afterannealing to enhance flatness and optimize magnetic propertiesduring the users lamination anneal.3.1.2 magnetic lamination steelsspecialty cold-rolled car-bon sheet steel melted to controlled levels of carbon withadditions of
11、manganese, phosphorus, silicon, and aluminum.Residual elements are generally held as low as possible. Theappropriate chemical composition combined with controlledmill processing results in a carbon sheet steel having mechani-cal properties and magnetic properties (after a quality devel-opment anneal
12、) desired for electrical applications.3.2 Other terms and symbols used in this specification aredefined in Terminology A 340.4. Ordering Information4.1 Orders for material under this specification shall includethe following information, as required, to describe the requiredmaterial adequately:4.1.1
13、ASTM specification number and date of issue.4.1.2 Core-loss type number.4.1.3 Finish (indicate typical profilometer range, as re-quired) (see 10.2).4.1.4 Specify not oiled or oiled, as required (see 10.4).1This specification is under the jurisdiction of ASTM Committee A06 onMagnetic Properties and i
14、s the direct responsibility of Subcommittee A06.02 onMaterial Specifications.Current edition approved Dec. 1, 2005. Published December 2005. Originallyapproved in 1976. Last previous edition approved in 2000 as A 726 00.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact
15、ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.4.1.5 Dimensions (nominal
16、thickness and coil width) andtolerances, if not standard (see 9.1).4.1.6 Coil size (must include limitations on inside diameterand maximum weight).4.1.7 Application (scroll slit for hermetic motors, and soforth).4.1.8 Special requirements (indicate hardness range, mag-netic limitations, and so forth
17、).4.1.9 Cast or heat analysis and magnetic test report (requestif required).NOTE 1A typical description is as follows: Cold-Rolled Sheet,Magnetic Lamination Steel, ASTM A 726 64D480, Surface Roughness50- to 80-in. (1.3- to 2.0-m) arithmetic average (RA), Not Oiled, 0.025by 49 in. (0.64 by 1245 mm) b
18、y coil, 24-in. (610-mm) inside diameter,20 000 lb (9000 kg) maximum, for fractional horsepower motors.5. Materials and Manufacture5.1 Melting PracticeThese steels are typically made bythe basic-oxygen or electric-furnace process.5.2 Typical Rolling and AnnealingThe processing se-quence for magnetic
19、lamination steel comprises hot rolling,pickling, cold rolling, annealing, and temper rolling.5.2.1 Magnetic lamination steels (all types) are cold reducedto thickness. The non-guaranteed core-loss type product canalso be sold in the as-annealed condition or after a temper millpass to flatten and to
20、impart the required surface texture(surface roughness). Magnetic lamination steels are usuallytemper rolled after box or continuous annealing to enhancemagnetic property development during the users laminationanneal. In addition, the temper pass is used to improve sheetflatness and punchability and
21、to obtain the required surfacetexture. Special emphasis may be placed on high extensions (2to 10 %) during the temper roll after annealing.5.2.2 When changes in the manufacture of the material arebelieved to exert possible significant effects upon the usersfabricating practices and upon the magnetic
22、 performance to beobtained in the specified end use, the producer shall notify theuser before shipment is made so that user has an opportunity toevaluate the effects.6. Chemical Composition6.1 Magnetic lamination steels have low-carbon contents.For the non-guaranteed core-loss type, the carbon conte
23、nt isless than 0.06 %. For higher quality core-loss types, the carboncontent is typically less than 0.04 % and may be reduced to lessthan 0.02 % by means of vacuum degassing, argon stirring, orother steel refining practices when such low-carbon contentsare required to facilitate decarburizing during
24、 annealing. Somemagnetic lamination steels are produced to carbon contents lessthan 0.005 %. In these steels, decarburization during annealingmay not be required.6.2 Magnetic lamination steels may have manganese, phos-phorus, silicon, and aluminum added to enhance punchabilityand to improve magnetic
25、 characteristics by increasing electri-cal resistivity. Other elements in small controlled amounts maybe used in the manufacture of these steels. In the past, the alloyadditions to magnetic lamination steels have been restrictedsuch that the density of the steel was maintained above 7.825g/cm3(7825
26、kg/m3). However, higher quality core-loss typemagnetic lamination steels may have alloy contents withdensity values less than 7.825 g/cm3(7825 kg/m3) andsubsequent testing for magnetic properties shall be in accor-dance with the procedure of Test Method A 343/A 343M (seeSection 12).6.3 Residual elem
27、ents found in steels are generally held aslow as practical.7. Magnetic Properties7.1 The magnetic properties of these steels are optimizedwhen the stamped laminations or assembled core structures areannealed to reduce the carbon content to 0.005 % or less. Toavoid sticking of laminations and assure
28、adequate decarburiza-tion, the annealing temperature should be in the range from1350 to 1500F (730 to 845C). Time at temperature will varywith lamination dimensions, charge size, surface finish, andannealing furnace characteristics. A partially combusted natu-ral gas atmosphere with suitable dew poi
29、nt is often used. Also,some users of lamination steels use a hydrogen-nitrogen gasmixture with a suitable dew point. For steel containing man-ganese, silicon, and aluminum, annealing conditions shall besuch that subsurface oxidation of these elements is minimized.7.2 Core losses of higher quality co
30、re-loss types are guar-anteed and shall conform to the limits given in Table 1.Relative peak permeability is a dimensionless quantity which isthe same in all unit systems. The typical values of relative peakpermeability for higher quality core-loss types are given inAppendix X1.8. Mechanical Propert
31、ies8.1 Hardness in the finished product depends on chemicalcomposition and mill processing. For the mill process annealedand temper rolled condition, hardness values typically rangefrom Rockwell 45 to 85 HRB.8.2 Specific ranges of hardness are subject to negotiationand should be specified on the ord
32、er.8.3 Rockwell hardness measurements are normally deter-mined by a superficial test (R30T and R15T) and converted toa B scale value in accordance with Test Methods E18 andTables E 140.8.4 When mechanical tests are required, test specimensshall be prepared and mechanical tests conducted in accor-dan
33、ce with Test Methods and Definitions A 370.9. Dimensions and Permissible Variations9.1 Tolerances for thickness, width, and camber applicableto magnetic lamination steels are shown in Table 2, Table 3,and Table 4.9.2 Thickness VariationsThe average thickness of thematerial supplied shall be as close
34、 as possible to the orderthickness. Measurements made with a contacting micrometerat points no closer than38 in. (10 mm) from the edge of a sheetor coil of specified width shall not differ from the specifiedthickness by more than the value (which includes taper) shownin Table 2.9.3 TaperThe rolling
35、of flat rolled sheets inherently pro-duces an edge which is thinner than the rest of the sheet. Thischaracteristic is termed tapered edge or feather or gamma andA726052occurs primarily within 1 or 2 in. (25 or 50 mm) from theas-rolled edge of the material. The thickness variation, classi-fied as edg
36、e taper, is often the major portion of the total overallthickness variation permitted in 9.2. It may be expected that inthe case of edge slit coils, the following limits on thedifferences in thickness measured within the first 2 in. (50 mm)or less from either edge of the ordered width will apply:Ord
37、ered Thickness Maximum Taperin. (mm) in. (mm)0.0185 (0.47) 0.0012 (0.030)0.025 (0.64) 0.0014 (0.035)More restricted cross-width thickness tolerances shall benegotiated between the producer and the user.TABLE 1 Core-Loss Types and Maximum Core-Loss Values at 15 Kilogauss (1.5 T) and 60 HzNOTE 1 Core-
38、loss values are developed after quality development anneal (QDA) at approximately 1450F (790C) to obtain thoroughly decarburized(0.005 % carbon) Epstein test specimens (with one half cut parallel and the other half cut perpendicular to the direction of rolling).NOTE 2Maximum core-loss values at 50 H
39、z are 0.79 3 maximum core-loss values at 60 Hz.SheetThickness,in. (mm)Core-LossTypeMaximumCore Loss,W/lbMaximumCore Loss,W/kg0.0185 (0.47) 47D175 1.75 3.8647D190 1.90 4.1947D215 2.15 4.7447D270 2.70 5.9547D330 3.30 7.2847D380 3.80 8.380.022 (0.56) 56D230 2.30 5.0756D260 2.60 5.7356D310 3.10 6.8456D3
40、80 3.80 8.3856D440 4.40 9.700.025 (0.64) 64D260 2.60 5.7364D290 2.90 6.4064D360 3.60 7.9464D430 4.30 9.4864D490 4.90 10.80.028 (0.71) 71D410 4.10 9.0471D480 4.80 10.671D550 5.50 12.10.031 (0.79) 79D450 4.50 9.9279D540 5.40 11.979D610 6.10 13.5TABLE 2 Thickness Tolerances, Cold-Rolled Sheet, Magnetic
41、 Lamination Steel for Specified Width 2 to 60 in. (50 to 1520 mm)InclusiveASpecifiedThicknessThickness Tolerance,Over and Underin. (mm) in. (mm)Over 0.039 to 0.057 incl (over 0.99 to 1.45 incl) 0.004 (0.10)Over 0.019 to 0.039, incl (over 0.48 to 0.99 incl) 0.003 (0.08)Over 0.014 to 0.019, incl (over
42、 0.36 to 0.48 incl) 0.002 (0.05)AThickness is measured at any point across the width not less than38 in. (10 mm) from a side edge.TABLE 3 Width Tolerances, Cold-Rolled Sheet, Magnetic Lamination SteelASpecified WidthWidth ToleranceOver Underin. (mm) in. (mm) in. (mm)2 to 6, incl (50 to 150, incl) 0.
43、008 (0.20) 0.008 (0.20)Over 6 to 9, incl (over 150 to 230, incl) 0.016 (0.41) 0.016 (0.41)Over 9 to 12, incl (over 230 to 300, incl) 0.032 (0.81) 0.032 (0.81)Over 12 to 30, incl (over 300 to 760, incl) 0.125 (3.2) 0 0Over 30 to 48, incl (over 760 to 1220, incl) 0.188 (4.8) 0 0Over 48 to 60, incl (ov
44、er 1220 to 1520, incl) 0.250 (6.4) 0 0AWidth tolerances for 2 to 12 in. (50 to 300 mm) inclusive apply to widths produced by slitting from wider sheet coils.A7260539.4 Because of the special processing treatments used forthese steels, ordinary flattening operations used for other steelproducts may n
45、ot be used due to their effects on magneticproperties. Special flatness requirements for a particular appli-cation should be made known on the purchase order.10. Workmanship, Finish, and Appearance10.1 The steel shall have a workmanlike appearance andshall be reasonably free of imperfections of a na
46、ture or degreethat will be detrimental to the fabrication of the finishedlamination. Coils may contain some abnormal imperfectionswhich render a portion of the coil unusable because theinspection of coils does not afford the producer an opportunityto remove portions containing imperfections.10.2 Mag
47、netic lamination steel is supplied with a surfacetexture produced by rolling on mill rolls which have beenroughened by mechanical, chemical, or electrical means tovarious degrees of surface texture. The roughened texturespromote decarburization and minimize sticking during thelamination anneal. Depe
48、nding upon the application require-ments, surface roughness is usually within the range from 40-to 160-in. (1.0- to 4.0-m) arithmetic average (RA) at 0.030-in. (0.76-mm) cutoff and 0.125-in./s (3.2-mm/s) tracing speedand a minimum 1-in. (25-mm) stroke.10.3 Cut edges made at the continuous pickler be
49、fore coldreduction (non-side trimmed last) will be furnished unlessotherwise specified.10.4 Magnetic lamination steel is customarily furnished notoiled (dry). If it is to be oiled, it must be so specified.11. Sampling11.1 Tests for magnetic properties, when required, shall betaken in a manner to assure representative sampling of the testlot. For quality control purposes, a test lot comprises one heatand it is usual practice to sample one coil from a cast or heat.Frequency of sampling when magnetic properties are guaran-teed shall be subject to negotiation.12. Te
