ASTM F31-21

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Designation: F31 − 16 F31 − 21
Standard Specification for
Nickel-Chromium-Iron Sealing Alloys
This standard is issued under the fixed designation F31; the number immediately following the designation indicates the year of original
adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript
epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This specification covers two iron-nickel-chromium alloys (UNS K94760 and UNS K95150) used primarily for glass-sealing
applications in electronic devices.
1.2 The values stated in inch-poundSI units are to be regarded as standard. The values given in parentheses are mathematical
conversions to after SI units that are provided for information only and are not considered standard.
1.3 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 safety, health, and healthenvironmental 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
2.1 ASTM Standards:
E18 Test Methods for Rockwell Hardness of Metallic Materials
E29 Practice for Using Significant Digits in Test Data to Determine Conformance with Specifications
E112 Test Methods for Determining Average Grain Size
E228 Test Method for Linear Thermal Expansion of Solid Materials With a Push-Rod Dilatometer
E354 Test Methods for Chemical Analysis of High-Temperature, Electrical, Magnetic, and Other Similar Iron, Nickel, and
Cobalt Alloys
F14 Practice for Making and Testing Reference Glass-Metal Bead-Seal
F140 Practice for Making Reference Glass-Metal Butt Seals and Testing for Expansion Characteristics by Polarimetric Methods
F144 Practice for Making Reference Glass-Metal Sandwich Seal and Testing for Expansion Characteristics by Polarimetric
Methods
3. Ordering Information
3.1 Orders for material under this specification shall include the following information:
3.1.1 Size,
This specification is under the jurisdiction of ASTM Committee F01 on Electronics and is the direct responsibility of Subcommittee F01.03 on Metallic Materials, Wire
Bonding, and Flip Chip.
Current edition approved May 1, 2016Nov. 1, 2021. Published May 2016December 2021. Originally approved in 1963 as F31 – 63 T. Last previous edition approved in
20122016 as F31 – 12.F31 – 16. DOI: 10.1520/F0031-16.10.1520/F0031-21.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
F31 − 21
3.1.2 Temper (Section 6),
3.1.3 Surface finish (Section 8),
3.1.4 Marking and packaging (Section 13), and
3.1.5 Certification if required.
4. Chemical Composition
4.1 The material shall conform to the requirements of Table 1 as to chemical composition.
TABLE 1 Chemical Composition
Element 42Ni-6Cr(UNS K94760) 47Ni-6Cr(UNS K95150)
Composition, % Composition, %
Nickel, nominal 42.0 47.0
Chromium, nominal 5.6 6.0
Carbon, max 0.07 0.02
Manganese, max 0.25 0.30
Phosphorus, max 0.025 0.025
Sulfur, max 0.025 0.025
Silicon, max 0.30 0.30
Aluminum, max 0.20 -
Iron remainder remainder
NOTE 1—The major constituents of this alloy may be adjusted by the manufacturer so that the alloy meets the requirement for thermal expansion.
5. Chemical Analysis
5.1 Chemical analysis shall be made, when desired, in accordance with Test Methods E354.
6. Surface Lubricants
6.1 All lubricants used during cold-working operations such as drawing, rolling, or spinning, shall be capable of being removed
readily by any of the common organic degreasing solvents.
7. Temper
7.1 The desired temper of the material shall be specified on the purchase order. Unless otherwise specified, wire, rod, and tubing
shall be given a final bright anneal by the manufacturer. Strip and sheet shall be annealed properly to develop drawing properties.
For deep drawing, the hardness shall not exceed Rockwell B90HRB 90 when determined in accordance with Test Methods E18.
8. Grain Size
8.1 Strip and sheet for deep drawing applications shall have an average grain size not larger than ASTM No. 5 (Note 2), with no
more than 10 % of the grains larger than No. 5 when measured in accordance with Test Methods E112. For materials less than
0.005 in. (0.13 mm)0.13 mm (0.005 in.) in thickness, the grain size shall be such that there are no less than 4 grains across the
thickness.
NOTE 2—This corresponds to a grain size finer than 0.065 mm or 16 grains/in.mm. of image at 100×.
9. Dimensional Tolerances
9.1 Cold-Rolled Strip—Cold-rolled strip shall conform to the permissible variations in dimensions prescribed in Table 2, Table 3,
and Table 4.
9.2 Round Wire and Rod—Wire and rod shall conform to the permissible variations in dimension prescribed in Table 5.
F31 − 21
TABLE 2 Permissible Variations in Thickness of Cold-Rolled Strip
NOTE 1—Measurement shall be made at least ⁄8 in. (9.5 mm) from the edge of strip over 1-in. (25.4 mm) wide.
Specified Thickness Permissible Variations in Thickness for Width Given, ±
in. (mm) Under 3 in. (Under 76 mm) Over 3 to 6 in. (76 to 150 mm)
0.160 to 0.100, incl (4.06 to 2.54) 0.002 (0.05) 0.003 (0.076)
0.099 to 0.069, incl (2.51 to 1.75) 0.002 (0.05) 0.003 (0.076)
0.068 to 0.050, incl (1.73 to 1.27) 0.002 (0.05) 0.003 (0.076)
0.049 to 0.035, incl (1.24 to 0.89) 0.002 (0.05) 0.0025 (0.064)
0.034 to 0.029, incl (0.86 to 0.74) 0.0015 (0.038) 0.002 (0.05)
0.028 to 0.026, incl (0.71 to 0.66) 0.0015 (0.038) 0.0015 (0.038)
0.025 to 0.020, incl (0.64 to 0.51) 0.001 (0.025) 0.0015 (0.038)
0.019 to 0.017, incl (0.48 to 0.43) 0.001 (0.025) 0.001 (0.025)
0.016 to 0.012, incl (0.41 to 0.30) 0.001 (0.025) 0.001 (0.025)
0.011 to 0.0101, incl (0.28 to 0.256) 0.001 (0.025) 0.001 (0.025)
0.010 to 0.0091, incl (0.254 to 0.231) 0.001 (0.025) 0.001 (0.025)
0.009 to 0.006, incl (0.228 to 0.152) 0.00075 (0.019) 0.00075 (0.019)
Under 0.006 (0.152) 0.0005 (0.013) 0.0005 (0.013)
TABLE 2 Permissible Variations in Thickness of Cold-Rolled Strip
NOTE 1—Measurement shall be made at least 9.5 mm ( ⁄8 in.) from the edge of strip over 25.4 mm (1-in.) in width.
Specified Thickness Permissible Variations in Thickness for Width Given, ±
mm (in.) Under 76 mm Over 76 to 150 mm Over 150 to 300 mm Over 300 to 400 mm (12
(3 in.) (3 to 6 in.) (6 to 12 in.) to 16 in.)
4.06 to 2.54, incl (0.160 to 0.100) 0.05 (0.002) 0.076 (0.003) 0.10 (0.004) 0.10 (0.004)
2.53 to 1.75, incl (0.100 to 0.069) 0.05 (0.002) 0.076 (0.003) 0.076 (0.003) 0.10 (0.004)
1.74 to 1.27, incl (0.068 to 0.050) 0.05 (0.002) 0.076 (0.003) 0.076 (0.003) 0.076 (0.003)
1.26 to 0.89, incl (0.050 to 0.035) 0.05 (0.002) 0.064 (0.0025) 0.076 (0.003) 0.076 (0.003)
0.88 to 0.74, incl (0.035 to 0.029) 0.038 (0.0015) 0.05 (0.002) 0.064 (0.0025) 0.064 (0.0025)
0.73 to 0.66, incl (0.029 to 0.026) 0.038 (0.0015) 0.038 (0.0015) 0.05 (0.002) 0.05 (0.002)
0.65 to 0.51, incl (0.026 to 0.020) 0.025 (0.001) 0.038 (0.0015) 0.05 (0.002) 0.05 (0.002)
0.50 to 0.43, incl (0.020 to 0.017) 0.025 (0.001) 0.025 (0.001) 0.038 (0.0015) 0.05 (0.002)
0.42 to 0.30, incl (0.017 to 0.012) 0.025 (0.001) 0.025 (0.001) 0.038 (0.0015) 0.038 (0.0015)
0.29 to 0.256, incl (0.011 to 0.010) 0.025 (0.001) 0.025 (0.001) 0.025 (0.001) 0.038 (0.0015)
0.255 to 0.231, incl (0.010 to 0.0091) 0.025 (0.001) 0.025 (0.001) 0.025 (0.001) 0.025 (0.001)
0.230 to 0.152, incl (0.0091 to 0.006) 0.019 (0.00075) 0.019 (0.00075) . .
Under 0.152 (0.006) 0.013 (0.0005) 0.013 (0.0005) . .
TABLE 3 Permissible Variation in Thickness Across Width of Strip
Specified Thickness Maximum Variation in Thickness Across Width of Strip, Within Those Provided for in Table 1 for
Edge Measurements for Widths and Thicknesses Given,
5 in. and Over 5 to
in. (mm) (127 mm and Under) (Over
Under 12 in.
0.005 to 0.010, incl (0.13 to 0.25) 0.00075 (0.019) 0.001
Over 0.010 to 0.025, incl (0.25 to 0.64) 0.001 (0.025) 0.0015
Over 0.025 to 0.065, incl (0.64 to 1.65) 0.0015 (0.038) 0.002
Over 0.065 to ⁄16, excl (1.65 to 4.74) 0.002 (0.051) 0.0025
TABLE 3 Permissible Variation in Thickness Across Width of Strip
Specified Thickness Maximum Variation in Thickness Across Width of Strip in mm (in.), Within Those Provided for in
Table 1 for Edge Measurements for Widths and Thicknesses Given
mm (in.) 127 mm (5 in.) Over 127 to 300 mm Over 300 to 600 mm
and Under (5 to 12 in.) (12 to 24 in.), incl
0.13 to 0.25, incl (0.005 to 0.010) 0.019 (0.00075) 0.025 (0.001) 0.038 (0.0015)
Over 0.25 to 0.64, incl (0.010 to 0.0
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