ASTM-F256 › Historical Revision Information
Standard Specification for Chromium-Iron Sealing Alloys with 18 or 28 Percent Chromium
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This specification covers two chromium-iron alloys, one is UNS K91800 with nominally 18% chromium, balance iron, and the other is UNS K92801 with nominally 28% chromium, both in strip, bar, wire, and rod forms intended primarily for sealing to glass in electronic applications. The alloys are classified by nominal chemical composition, specifically by chromium content, in two types: Type I (UNS K91800) and Type II (UNS K92801). The materials shall show no evidence of transformation to martensite. For Type I alloy, the austenite formed during heat treating will transform to martensite at or above room temperature. The presence of austenite, as may be noted in Type II alloy, is acceptable if the thermal expansion requirement is met. Different tests shall be performed in order to determine the following properties of the alloys: thermal expansion, Rockwell hardness, and tensile strength.
Scope
1.1 This specification covers two chromium-iron alloys, the former, (UNS K91800), nominally 18 % chromium, balance iron, the latter, (UNS K92801), nominally 28 % chromium, in strip, bar, wire, and rod forms intended primarily for sealing to glass in electronic applications.
Note 1—UNS K92801 should only be considered for use at service temperatures below 300°C. The alloy is prone to sigma phase formation at temperatures close to 620°C, and exhibits brittle mechanical behavior after prolonged exposures at temperatures close to 475°C.
1.2 The values stated in inch-pound units are to be regarded as the standard. The values given in parentheses are for information only.
1.3 The following hazard caveat pertains only to the test method portion, Sections 16 and 17, of this specification. This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
Keywords
glass-to-metal sealing; iron-chromium alloys; UNS K91800; UNS K; ICS Number Code 2801; 21.140 (Seals, glands)
To find similar documents by ASTM Volume:
10.04 (Electronics; Declarable Substances in Materials; 3D Imaging Systems)
To find similar documents by classification:
21.140 (Seals, glands Seals for pipe and hose assemblies, see 23.040.80)
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Document Number
ASTM-F256-05e1
Revision Level
2005(E1) EDITION
Status
Superseded
Modification Type
Editorially changed
Publication Date
Aug. 1, 2005
Document Type
Specification
Page Count
7 pages
Committee Number
F01.03