ASTM F256-05(2020) - 1.5.2020
 
1. 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 standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.

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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

 
2. Referenced Documents

A370-23

Standard Test Methods and Definitions for Mechanical Testing of Steel Products

E3-11(2017)

Standard Guide for Preparation of Metallographic Specimens

E18-22

Standard Test Methods for Rockwell Hardness of Metallic Materials

E38-85

Methods for Chemical Analysis of Nickel-Chromium and Nickel-Chromium-Iron Alloys (Withdrawn 1989)

F140-98(2020)

Standard Practice for Making Reference Glass-Metal Butt Seals and Testing for Expansion Characteristics by Polarimetric Methods

F144-80(2019)

Standard Practice for Making Reference Glass-Metal Sandwich Seal and Testing for Expansion Characteristics by Polarimetric Methods

E29-22

Standard Practice for Using Significant Digits in Test Data to Determine Conformance with Specifications

E228-22

Standard Test Method for Linear Thermal Expansion of Solid Materials With a Push-Rod Dilatometer

F14-80(2019)

Standard Practice for Making and Testing Reference Glass-Metal Bead-Seal