1、Designation:F25605(Reapproved 2015)Standard Specification forChromium-Iron Sealing Alloys with 18 or 28 PercentChromium1This standard is issued under the fixed designation F256;the number immediately following the designation indicates the year of originaladoption or,in the case of revision,the year
2、 of last revision.Anumber in parentheses indicates the year of last reapproval.Asuperscriptepsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This specification covers two chromium-iron alloys,theformer,(UNS K91800),nominally 18%chromium,balanceiron,the latter,(U
3、NS K92801),nominally 28%chromium,instrip,bar,wire,and rod forms intended primarily for sealing toglass in electronic applications.NOTE1UNS K92801 should only be considered for use at servicetemperatures below 300C.The alloy is prone to sigma phase formation attemperatures close to 620C,and exhibits
4、brittle mechanical behaviorafter prolonged exposures at temperatures close to 475C.1.2 The values stated in inch-pound units are to be regardedas standard.The values given in parentheses are mathematicalconversions to SI units that are provided for information onlyand are not considered standard.1.3
5、 The following hazard caveat pertains only to the testmethod portion,Sections 16 and 17,of this specification.Thisstandard does not purport to address all of the safety concerns,if any,associated with its use.It is the responsibility of the userof this standard to establish appropriate safety and he
6、althpractices and determine the applicability of regulatory limita-tions prior to use.2.Referenced Documents2.1 ASTM Standards:2A370 Test Methods and Definitions for Mechanical Testingof Steel ProductsE3 Guide for Preparation of Metallographic SpecimensE18 Test Methods for Rockwell Hardness of Metal
7、lic Ma-terialsE29 Practice for Using Significant Digits in Test Data toDetermine Conformance with SpecificationsE38 Methods for Chemical Analysis of Nickel-Chromiumand Nickel-Chromium-Iron AlloysE228 Test Method for Linear Thermal Expansion of SolidMaterials With a Push-Rod DilatometerF14 Practice f
8、or Making and Testing Reference Glass-MetalBead-SealF140 Practice for Making Reference Glass-Metal Butt Sealsand Testing for Expansion Characteristics by PolarimetricMethodsF144 Practice for Making Reference Glass-Metal SandwichSeal and Testing for Expansion Characteristics by Polari-metric Methods3
9、.Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 bar:3.1.1.1 hot-finished rounds,squares,and hexagons,14in.(6.4 mm)and over in diameter or size.3.1.1.2 hot-finished flats,14in.to 10 in.(6.4 to 254 mm),inclusive,in width and18in.(3.2 mm)and over in thickness.3.1.1.3 cold-finished
10、rounds,squares,octagons,hexagonsand shapes,over12in.(12.7 mm)in diameter or size.3.1.1.4 cold-finished flats,38in.(9.5 mm)and over in widthand18in.(3.2 mm)and over in thickness(see Discussions).DiscussionWidths less than38in.(9.5 mm)and thick-nesses less than316in.(4.8 mm)are generally described as
11、flatwire.DiscussionThicknesses of18in.(3.2 mm)to under316in.(4.8 mm)can also be described as cold-rolled strip or,if in cutlengths,bar.3.1.2 rodhot-rolled,or hot-rolled,annealed,and pickled,rounds,squares,octagons,hexagons and shapes,in coils,forsubsequent cold drawing or cold rolling,14in.or34in.(6
12、.4 or19.0 mm)in diameter or size.3.1.3 stripcold-finished coils or cut lengths,under 24 in.(610 mm)down to and including316in.(4.8 mm)in width,andunder316in.down to and including 0.005 in.(0.13 mm)inthickness.3.1.4 No.1 edgea rolled edge either round or square asspecified.3.1.5 No.3 edgean edge prod
13、uced by slitting.3.1.6 No.5 edgean approximately square edge producedby rolling or filing after slitting.1This specification is under the jurisdiction of ASTM Committee F01 onElectronics and is the direct responsibility of Subcommittee F01.03 on MetallicMaterials,Wire Bonding,and Flip Chip.Current e
14、dition approved July 1,2015.Published October 2015.Originallyapproved in 1951 as F256 51 T.Last previous edition approved in 2010 asF256 94(2010).Consolidated with F257 in 1972.DOI:10.1520/F0256-05R15.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service
15、at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 DiscussionCold-finished product 0.005 in.(0.13 mm)inthi
16、ckness and under 24 in.(609.6 mm)in width is sometimesidentified as foil.3.1.7 wire:3.1.7.1 cold finished only,round or square,12in.(12.7 mm)and under in diameter or size.3.1.7.2 cold finished only,flat wire of116in.(1.6 mm)tounder38in.(9.5 mm)in width and 0.010 in.(0.25 mm)tounder316in.(4.8 mm)in thickness.4.Classification4.1 The alloys covered by this specification are classified bynominal chemical composition,specifically by chromiumcontent,in two types:4.1.1 Type I18%chromium(UNS K91800)and4
