1、Designation: A 904 04Standard Specification for50 Nickel-50 Iron Powder Metallurgy (P/M) Soft MagneticParts1This standard is issued under the fixed designation A 904; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last
2、 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 the magnetic properties of 50nickel-50 iron parts fabricated by powder metallurgy tech-niques a
3、nd is intended for parts that require high magneticpermeability, high electrical resistivity, low coercive fieldstrength, and low hysteresis loss. It differs from the wroughtalloy specification (see Specification A 753) because theseparts are porous. A number of magnetic properties such aspermeabili
4、ty are proportional to the sintered density.1.2 This specification deals with P/M parts in the sintered orannealed condition. Should the sintered parts be subjected toany secondary operation that causes mechanical strain, such asmachining or sizing, they should be resintered or annealed.1.3 The valu
5、es stated in customary (cgs-emu and inch-pound) units are to be regarded separately as standard. Thevalues given in parentheses are mathematical conversions to SIunits, which are provided for information only and are notconsidered standard.2. Referenced Documents2.1 ASTM Standards:2A 34/A 34M Practi
6、ce for Sampling and Procurement Test-ing of Magnetic MaterialsA 340 Terminology of Symbols and Definitions Relating toMagnetic TestingA 596/A 596M Test Method for Direct-Current MagneticProperties of Materials Using the Ballistic Method andRing SpecimensA 753 Specification for Wrought Nickel-Iron So
7、ft MagneticAlloys (UNS K94490, K94840, N14076, N14080)A 773/A 773M Test Method for dc Magnetic Properties ofMaterials Using Ring and Permeameter Procedures withdc Electronic HysteresigraphsB 328 Test Method for Density, Oil Content and Intercon-nected Porosity of Sintered Powder Metal Structural Par
8、tsand Oil-Impregnated BearingsE 1019 Test Methods for Determination of Carbon, Sulfur,Nitrogen, and Oxygen in Steel and in Iron, Nickel andCobalt Alloys3. Terminology3.1 The terms and symbols used in this specification aredefined in Terminology A 340.4. Ordering Information4.1 Orders for parts confo
9、rming to this specification shallinclude the following information.4.1.1 Reference to this standard and year of issue/revision.4.1.2 Reference to an applicable part drawing.4.1.3 Quantity required.4.1.4 A critical cross section of the part shall be defined andso indicated on the applicable part draw
10、ing. The location of thecritical section is by mutual agreement between the user andproducer (see 6.2).4.1.5 Magnetic property requirements if they are other thanstated in 7.5.4.1.6 Certification of chemical composition or magneticproperty evaluation, or both (Sections 5 and 7).4.1.7 Marking and pac
11、kaging requirements (Section 12).4.1.8 Exceptions to this specification or special require-ments such as functional testing as mutually agreed upon bythe producer and user.5. Chemical Composition5.1 The chemical composition of the parts shall conform tothe requirements prescribed in Table 1.5.2 Dete
12、rmination of metallic constituents shall be by amethod acceptable to both producer and user. Analysis ofcarbon, nitrogen, sulfur, and oxygen shall be done in accor-dance with Test Methods E 1019.1This specification is under the jurisdiction of ASTM Committee A06 onMagnetic Properties and is the dire
13、ct responsibility of Subcommittee A06.02 onMaterial Specifications.Current edition approved May 1, 2004. Published June 2004. Originallyapproved in 1990. Last previous edition approved in 1998 as A 904 98.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer S
14、ervice 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.6. Sintered Density Requirements6.1 Magne
15、tic and residual induction of P/M parts stronglydepend on density. The density of P/M parts is determined bythe compressibility of the powder, the compacting pressure,and sintering practice (temperature, time, and atmosphere).6.2 Parts produced in conformance with this specificationshall have a mini
16、mum sintered density of 6.99 g/cm3(6990kg/m3) in the critical section of the part. The critical sectionshall be defined by agreement between the user and producer.6.3 Sintered density shall be determined in accordance withTest Method B 328.7. Magnetic Property Requirements7.1 Because of the nature o
17、f P/M parts production, magnetictesting of each lot is not required by this specification.However, it is strongly recommended that the user require theproducer to conduct periodic magnetic evaluations and tocertify such results. Such magnetic property evaluations shallbe conducted in the manner desc
18、ribed below.7.2 When requested, each lot of parts should be sinteredwith at least one and preferably three ring test specimens whichcomply with the geometric requirements listed in PracticeA 34/A 34M. The ring specimen(s) shall be produced from thesame mixed lot of powder used to produce the parts.7
19、.3 The magnetic properties shall be determined in accor-dance with Test Methods A 596/A 596M or A 773/A 773M.7.4 For the purpose of this specification, only the coercivefield strength determined from a maximum applied magneticfield strength of 15 Oe (1200 A/m) needs to be determined.Other magnetic p
20、roperties may be specified by mutual agree-ment between the user and producer.7.5 Coercive Field Strength RequirementsParts suppliedto this specification shall exhibit a maximum coercive fieldstrength of 0.4 Oe (32 A/m).7.6 Since magnetic properties are strongly affected byprocess conditions, refer
21、to the appendixes for typical valuesand explanatory notes.8. Workmanship, Finish and Appearance8.1 The parts shall be uniform in composition and uniformin density within critical sections.8.2 If parts are sectioned or fractured, there shall be noreadily recognizable defects.9. Sampling9.1 A lot shal
22、l consist of parts of the same form anddimensions, produced from a single mixed powder batch andfrom an unchanged process, without discontinuity in produc-tion, and submitted for inspection at one time.9.2 The user and producer shall agree upon a representativenumber of specimens for testing.10. Rej
23、ection and Rehearing10.1 Parts that fail to conform to the requirements of thisspecification shall be rejected. Rejection should be reported tothe producer promptly and in writing. In case of dissatisfactionwith the results of the test, the producer may make claim for arehearing.10.2 The disposition
24、 of rejected parts shall be subject toagreement between the user and producer.11. Certification11.1 When specified in the purchase order or contract, theuser shall be furnished certification that samples representingeach lot have either been tested or inspected as directed in thisspecification and t
25、he requirements have been met.11.2 When specified in the purchase order or contract, areport of the test results shall include:11.2.1 Chemical composition,11.2.2 Part density in the critical section,11.2.3 Magnetic test results, if required by user, and11.2.4 The results of any other tests stipulate
26、d in thepurchase order or contract.12. Packaging and Package Marking12.1 Packaging shall be subject to agreement between theuser and producer.12.2 Parts furnished under this specification shall be in acontainer identified by the name or symbol of the partsproducer.13. Keywords13.1 coercive field str
27、ength; PIM parts; powder metallurgy(PIM); 50 Ni-50 FeTABLE 1 Chemical Composition Requirements(in Weight Percent)Element %Nickel 46 -51Carbon 0.02 maxOxygen 0.10 maxNitrogen 0.01 maxOthersA0.5 maxIronBbalanceAOthers refers to trace elements that are to be regarded as incidental and notdeliberate add
28、itions.BIron is the balance by difference. Quantitative analysis of this element is notrequired.A904042APPENDIXES(Nonmandatory Information)X1. TYPICAL MAGNETIC PROPERTIESX1.1 Typical dc magnetic properties, based on interlabora-tory studies, are listed in Table X1.1. These results wereobtained using
29、 a sintering practice of 2300F (1260C) in dryhydrogen or in vacuum. The influence of sintered density isshown. The data provided are for information only and are notrequirements in this specification.X1.2 Maximum flux density, residual induction, and coer-cive field strength are measured from a maxi
30、mum appliedmagnetic field strength of 15 Oe (1200 A/m).X2. HEAT TREATMENT OF MAGNETIC TEST SPECIMENS AND PARTSX2.1 The magnetic properties within this specification arefor as-sintered parts. As such, the magnetic properties may notbe at optimum values especially the relative maximum perme-ability an
31、d coercive field strength. To achieve optimum prop-erties, the parts must be annealed to promote grain growth.X2.2 A general heat treatment to improve magnetic prop-erties is as follows:X2.2.1 Place parts in a sealed retort or equivalent,X2.2.2 Introduce a circulated dry hydrogen atmospherehaving an
32、 entrance dewpoint of 60F (51C) or lower,X2.2.3 Heat to a temperature of 2050 to 2160F (1120 to1180C) and hold for4hattemperature, andX2.2.4 Cool to room temperature at a rate not to exceed200F/h (110C/h).ASTM International takes no position respecting the validity of any patent rights asserted in c
33、onnection 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 revision at any time by the resp
34、onsible 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. Your comments will receive carefu
35、l 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,
36、 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the AST
37、M website(www.astm.org).TABLE X1.1 Typical dc Magnetic PropertiesSintered Density,g/cm3(kg/m3)7.0 (7000) 7.3 (7300) 7.5 (7500)Relative MaximumPermeability8100 9400 9900Maximum flux density, G 9000 10000 11000(T) 0.9 1.0 1.1Residual Induction, G 7500 8500 9000(T) 0.75 0.85 0.90Coercive Field Strength, Oe 0.3 0.3 0.3(A/m) 24 24 24A904043
