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.

Designation: F594 − 22

Standard Specification for

Stainless Steel Nuts1
This standard is issued under the fixed designation F594; 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.
This standard has been approved for use by agencies of the U.S. Department of Defense.

1. Scope* 1.6 This standard does not purport to address all of the
1.1 This specification covers the requirements for stainless safety concerns, if any, associated with its use. It is the
steel nuts 0.25 to 1.50 in., inclusive, in nominal diameter in a responsibility of the user of this standard to establish appro-
number of alloys in common use and intended for service priate safety, health, and environmental practices and deter-
applications requiring general corrosion resistance. mine the applicability of regulatory limitations prior to use.
1.7 This international standard was developed in accor-
1.2 Seven groups of stainless steel alloys are covered, dance with internationally recognized principles on standard-
including ten austenitic, two ferritic, four martensitic, and one ization established in the Decision on Principles for the
precipitation hardening. Development of International Standards, Guides and Recom-
Group AlloysA ConditionB mendations issued by the World Trade Organization Technical
1 304, 305, 304L (CW) cold workedD
Barriers to Trade (TBT) Committee.
384, 18–9LW, 302HQC

iTeh Standards
2 316, 316L (CW) cold workedD 2. Referenced Documents
3 321, 347 (CW) cold workedD 2
4 430E (CW) 2.1 ASTM Standards:
cold workedD

(https://standards.iteh.ai)
5 410F (H) A262 Practices for Detecting Susceptibility to Intergranular
hardened and tempered
6 431 (H) hardened and tempered
Attack in Austenitic Stainless Steels
7 630 (AH) aged hardened
A342/A342M Test Methods for Permeability of Weakly
A
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Magnetic Materials
Unless otherwise specified on the inquiry and order, the choice of an alloy from
A380 Practice for Cleaning, Descaling, and Passivation of
within a group shall be at the discretion of the fastener manufacturer (see 6.1).
B
See 4.2 for options. Stainless Steel Parts, Equipment, and Systems
C
When approved by the purchaser, alloys 303, 303Se, or XM1 may be furnished.
A493 Specification for Stainless Steel Wire and Wire Rods
ASTM F594-22 for Cold Heading and Cold Forging
D
Sizes 0.75 in. and larger may be hot worked and solution annealed.
E
When approved by the purchaser, alloy 430F may be furnished.
F
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When approved by the purchaser, alloy 416 or 416Se may be furnished.
A555/A555M Specification for General Requirements for
1.3 Supplementary requirements of an optional nature are Stainless Steel Wire and Wire Rods
provided, applicable only when agreed upon by the manufac- A564/A564M Specification for Hot-Rolled and Cold-
turer and the purchaser at the time of the inquiry and order. Finished Age-Hardening Stainless Steel Bars and Shapes
1.4 Suitable bolts, hex cap screws, and studs for use with A582/A582M Specification for Free-Machining Stainless
nuts included in this specification are covered by Specification Steel Bars
F593. Unless otherwise specified, all bolts, hex cap screws, and A751 Test Methods and Practices for Chemical Analysis of
studs used with these nuts shall conform to the requirements of Steel Products
Specification F593 and shall be of the same alloy group. D3951 Practice for Commercial Packaging
E29 Practice for Using Significant Digits in Test Data to
1.5 The values stated in inch-pound units are to be regarded Determine Conformance with Specifications
as standard. The values given in parentheses are mathematical F593 Specification for Stainless Steel Bolts, Hex Cap
conversions to SI units that are provided for information only Screws, and Studs
and are not considered standard. F606/F606M Test Methods for Determining the Mechanical
Properties of Externally and Internally Threaded
Fasteners, Washers, Direct Tension Indicators, and Rivets
1
This specification is under the jurisdiction of ASTM Committee F16 on
Fasteners and is the direct responsibility of Subcommittee F16.04 on Nonferrous
2
Fasteners. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Nov. 1, 2022. Published January 2023. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 1978. Last previous edition approved in 2020 as F594 – 09(2020). DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/F0594-22. the ASTM website.

*A Summary of Changes section appears at the end of this standard

Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States

1
 F594 − 22
E1470 Test Method for Characterization of Proteins by Condition Furnished
Electrophoretic Mobility (Withdrawn 2014)3 Alloy Group Unless Otherwise Optional Conditions
Specified (must be specified)
4
2.2 ASME Standards:
B1.1 Unified Inch Screw Threads 1, 2, 3 CW AF, A, SH
4 CW A
B18.2.2 Square and Hex Nuts 5 H HT
6 H HT
NOTE 1—The following ASTM standards are noted for information 7 AH none
only as suitable sources of material for the manufacture of nuts to this A— Machined from annealed or solution annealed stock thus
specification: retaining the properties of the original material; or hot formed
Specifications A493, A564/A564M, and A582/A582M. and solution annealed.
AF— Annealed after all threading is completed.
3. Ordering Information AH— Solution annealed and age hardened after forming.
CW— Annealed and cold worked. Sizes 0.75 in. and larger may be
3.1 Orders for nuts under this specification shall include the hot worked and solution annealed.
H— Hardened and tempered at 1050 °F (565 °C) minimum.
following: HT— Hardened and tempered at 525 °F (274 °C) minimum.
3.1.1 Quantity (number of pieces of each item and size), SH— Machined from strain hardened stock.

3.1.2 Name of item, 5. Heat Treatment

3.1.3 Size (diameter and threads per inch), 5.1 Alloy Groups 1, 2, and 3 (Austenitic Alloys 303, 303Se,
3.1.4 Alloy group number (see 6.2.1), and 304, 304L, 305, 316, 316L, 321, 347, 384, XM1, 18–9LW, and
3.1.5 Condition (see 4.2). 302HQ):
3.1.6 Orders for nuts under this specification may include 5.1.1 Condition A—When Condition A is specified, the
the following optional requirements: austenitic alloys shall be heated to 1900 6 50 °F (1038 6
3.1.6.1 Forming (see 4.1.1), 28 °C), at which time the chromium carbide will go into the
3.1.6.2 Composition (see 6.2), solution, be held for a sufficient time, and then be cooled at a
3.1.6.3 Corrosion resistance (see 8.1), rate sufficient to prevent precipitation of the carbide and to

iTeh Standards
provide the specified properties.
3.1.6.4 Thread class (see 9.2),
5.1.2 Condition CW—When Condition CW is specified, the
3.1.6.5 Finish (see 10.3), austenitic alloys shall be annealed as specified in 5.1.1 and then
3.1.6.6 Test report (see 17.2),
3.1.6.7 Rejection (see 16.1), (https://standards.iteh.ai) cold worked to develop the specified properties.
5.1.3 Condition AF—When Condition AF is specified, the

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3.1.6.8 Test rejection (see 16.1), and austenitic alloys shall be annealed as specified in 5.1.1 after all
3.1.6.9 Special packaging (see 19.2). cold working, including forming and threading.
3.1.7 Supplementary requirements, if any, to be specified on 5.2 Alloy Group 4 (Ferritic Alloys 430 and 430F):
the order (see S1 through S8), and 5.2.1 Condition A—The ferritic alloys shall be heated to a
3.1.8 ASTM specification and date of issue. When date of ASTM F594-22
temperature of 1450 6 50 °F (788 6 28 °C), held for an
issuehttps://standards.iteh.ai/catalog/standards/sist/a87ac2f1-610f-4673-8744-b30723735ff8/astm-f594-22
is not specified, fasteners shall be furnished to the latest appropriate time, and then air cooled to provide the specified
issue. properties.
5.2.2 Condition CW—When Condition CW is specified, the
NOTE 2—Example: 10 000 pieces, Hex Nut, 0.250 in. −20, Alloy Group ferritic alloys shall be annealed in accordance with 5.2.1,
1, Condition CW, Furnish Test Report, Supplementary Requirement S3.
generally by the raw material manufacturer, and then cold
worked to develop the specified properties.
4. Manufacture
5.3 Alloy Group 5 (Martensitic Alloys 410, 416, and 416Se):
4.1 Manufacture: 5.3.1 Condition H—When Condition H is specified, the
4.1.1 Forming—Unless otherwise specified, the nuts shall martensitic alloys 410, 416, and 416Se shall be hardened and
be hot formed, cold formed, or machined from suitable tempered by heating to 1850 6 50 °F (1010 6 28 °C) sufficient
material, at the option of the manufacturer. for austenitization, held for at least 1⁄2 h and rapid air- or
4.2 Condition—The fasteners shall be furnished in the oil-quenched, then reheating to 1050 °F (565 °C) minimum for
following conditions, unless specified to be furnished in one of at least 1 h and air cooled to provide the specified properties.
the optional conditions: 5.3.2 Condition HT—When Condition HT is specified, the
martensitic alloys 410, 416, and 416Se shall be hardened and
tempered by heating to 1850 6 50 °F (1010 6 28 °C) sufficient
3
for austenitization, held for at least 1⁄2 h and rapid air- or
The last approved version of this historical standard is referenced on
oil-quenched, then reheating to 525 °F (274 °C) minimum for
www.astm.org.
4
Available from Global Engineering Documents, 15 Inverness Way, East at least 1 h and air cooled to provide the specified properties.
Englewood, CO 80112-5704, http://www.global.ihs.com..

2
 F594 − 22
5.4 Alloy Group 6 (Martensitic Alloy 431): 8. Corrosion Resistance
5.4.1 Conditions H and HT—The martensitic alloy 431 shall 8.1 Carbide Precipitation:
be hardened and tempered as specified in 5.3.1 and 5.3.2 as 8.1.1 Rod, bar, and wire in the austenitic Alloy Groups 1, 2,
applicable. and 3, except the free-machining grades, 303 and 303Se used
5.5 Alloy Group 7 (Precipitation Hardening Alloy 630): to make fasteners in accordance with this specification, shall be
5.5.1 Condition AH—The precipitation hardening alloy 630 capable of passing the test for susceptibility to intergranular
shall be solution annealed and aged by heating to 1900 6 25 °F corrosion as specified in Practice E of Practice A262.
(1038 6 14 °C) for at least 1⁄2 h and rapid air or oil quenched 8.1.2 As stated in Practice A262, samples may be subjected
to 80 °F (27 °C) maximum, then reheating to a temperature of to the faster and more severe screening test in accordance with
1150 6 15 °F (621 6 8 °C) for 4 h and air cooled to provide Practice A. Failing Practice A, specimens may be tested in
the specified properties. accordance with Practice E and be considered satisfactory if
passing Practice E.
6. Chemical Composition
9. Dimensions
6.1 Alloy Groups—It is the intent of this specification that
fasteners shall be ordered by alloy group numbers that include 9.1 Nuts:
alloys considered to be chemically equivalent for general 9.1.1 Unless otherwise specified, the dimensions shall be in
purpose use. The alloy groupings are as shown below. When accordance with the requirements of ASME B18.2.2 for Hex
required, however, a specific alloy may be specified as permit- Nuts.
ted by 6.2.2. 9.1.2 When specified, the dimensions of nuts shall be in
Alloy Group Alloys
accordance with the requirements of ASME B18.2.2 (type as
specified), or such other dimensions as may be specified.
1 304, 305, 304L
384, 18–9LW, 302HQA
9.2 Threads (see Table 4)—Unless otherwise specified, the
2 316, 316L nuts shall have Class 2B threads in accordance with ASME
3 321, 347 B1.1.
4 430B
5
6
7
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410C
431
630
10. Workmanship, Finish, and Appearance
10.1 Workmanship—The nuts shall have a workmanlike
A
B
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finish, free of injurious burrs, seams, laps, irregular surfaces,
When approved by the purchaser, alloys 303, 303Se, or XM1 may be furnished.
and other defects affecting serviceability.
When approved by the purchaser, alloy 430F may be furnished.

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C
10.2 Surface Finish—The nuts shall have a surface finish
When approved by the purchaser, alloys 416 or 416Se may be furnished.

6.2 Chemical Composition Limits: produced in accordance with Practice A380.

6.2.1 Ordering by Alloy Group—Unless otherwise specified 10.3 Protective Finishes—Unless otherwise specified, the
on the inquiry and order (see Supplementary Requirement S4), nuts shall be furnished without an additive chemical or metallic
the choice of an alloy from within a group shallASTM F594-22
be at the finish.
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discretion of the fastener manufacturer as required by his
11. Sampling
method of fastener fabrication and material availability. The
specific alloy used by the fastener manufacturer shall be clearly 11.1 A lot, for the purposes of selecting test specimens, shall
identified on any certification required by the order and shall consist of not more than 100 000 pieces offered for inspection
have a chemical composition conforming to the requirements at one time having the following common characteristics:
of Table 1 for the specific alloy. 11.1.1 One type of item,
6.2.2 Ordering by Specific Alloy—When ordered by a spe- 11.1.2 Same alloy and condition, and
cific alloy number, the fasteners shall conform to the chemical 11.1.3 One nominal diameter and thread series.
composition limits of Table 1 for the specific alloy. 12. Number of Tests and Retests
6.3 Product Analysis: 12.1 Number of Tests:
6.3.1 Product analysis may be made by the purchaser from 12.1.1 Mechanical Tests—The mechanical requirements of
finished nuts representing each lot. The chemical composition this specification shall be met in continuous mass production
thus determined shall conform to the requirements of Table 1 for stock. The manufacturer shall make sample inspections as
for the specific alloy subject to the Product Analysis Tolerance specified below to ensure the product conforms to the specified
in Specification A555/A555M. requirements. When tests of individual shipments are required,
6.3.2 In the event of discrepancy, a referee chemical analy- Supplementary Requirement S1 must be specified in the
sis of samples from each lot shall be made in accordance with inquiry and order.
14.1. Acceptance Criteria
Number of Pieces in Lot Number Acceptance Rejection
7. Mechanical Properties of Tests Number Number
7.1 The finished fasteners shall meet the applicable me-
2 to 50 2 0 1
chanical properties of Table 2 for the specified alloy group and 51 to 500 3 0 1
condition when tested in accordance with the mechanical 501 to 35 000 5 0 1
property requirements as specified herein (see also Table 3). 35 001 to 100 000 8 0 1

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 F594 − 22
TABLE 1 Chemical Requirements
UNS Composition, % maximum except as shown, ellipses indicate no requirement for listed element
Alloy Desig- Alloy Manga- Phos- Others
Group nation Carbon Sulfur Silicon Chromium Nickel Copper Molybdenum
nese phorus
Austenitic Alloys
1 S30300 303 0.15 2.00 0.20 0.15 min 1.00 17.0 to 8.0 to ... 0.60A ...
19.0 10.0
1 S30323 303Se 0.15 2.00 0.20 0.060 1.00 17.0 to 8.0 to ... ... Se 0.15 min
19.0 10.0
B
1 S30400 304 0.08 2.00 0.045 0.030 1.00 18.0 to 8.0 to ... ...
20.0 10.5
B
1 S30403 304L 0.03 2.00 0.045 0.030 1.00 18.0 to 8.0 to ... ...
20.0 12.0
B
1 S30500 305 0.12 2.00 0.045 0.030 1.00 17.0 to 10.0 to ... ...
19.0 13.0
1 S38400 384 0.08 2.00 0.045 0.030 1.00 15.0 to 17.0 to ... ... ...
17.0 19.0
1 S20300 XM1 0.08 5.0 to 6.5 0.040 0.18 to 1.00 16.0 to 5.0 to 1.75 to 0.50 ...
0.35 18.0 6.5 2.25
1 S30430 18–9LW 0.10 2.00 0.045 0.030 1.00 17.0 to 8.0 to 3.0 to 4.0 ... ...
19.0 10.0
1 S30433 302HQ 0.03 2.00 0.045 0.030 1.00 17.0 to 8.0 to 3.0 to 4.0 ... ...
19.0 10.0
2 S31603 316L 0.03 2.00 0.045 0.030 1.00 16.0 to 10.0 to ... 2.00–3.00 ...
18.0 14.0
2 S31600 316 0.08 2.00 0.045 0.030 1.00 16.0 to 10.0 to ... 2.00–3.00 ...
18.0 14.0
3 S32100 321 0.08 2.00 0.045 0.030 1.00 17.0 to 9.0 to ... ... Ti 5 × C
19.0 12.0 min
3 S34700 347 0.08 2.00 0.045 0.030 1.00 17.0 to 9.0 to ... ... Nb
19.0 13.0 10 × C
minC

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Ferritic Alloys
4 S43000 430 0.12 1.00 0.040 0.030 1.00 16.0 to ... ... ...
S43020 430F 0.12 1.25 0.060 0.15 min 1.00 18.0 0.60A

(https://standards.iteh.ai)
16.0 to
18.0
Martensitic Alloys
5 S41000 410 0.15 1.00 0.040 0.030 1.00 11.5 to ... ... ... ...

5 S41600 416 Document Preview

0.15 1.25 0.060 0.15 min 1.00
13.5
12.0 to
14.0
... ... 0.60 A
...

5 S41623 416Se 0.15 1.25 0.060 0.060 1.00 12.0 to ... ... ... Se 0.15 min
14.0
ASTM F594-22
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6 S43100 431 0.20 1.00
0.030 0.040
1.00 15.0 to
17.0
1.25 to
2.50
... ... ...

Precipitation Hardening Alloy

7 S17400 630 0.07 1.00 0.040 0.030 1.00 15.0 to 3.0 to 3.0 to 5.0 ... Nb
17.5 5.0 0.15–0.45C
A
At manufacturer’s option, determined only when intentionally added.
B
1.00 % Cu max allowed by this standard for formability at manufacturer’s option.
C
Niobium formerly known as Colombium (Cb).

12.1.2 Corrosion Resistance Tests: 12.2.2 If the failure of a test specimen is due to improper
12.1.2.1 Unless otherwise specified, tests for corrosion re- preparation of the specimen or to incorrect testing technique,
sistance shall be in accordance with the manufacturer’s stan- the specimen shall be discarded and another specimen substi-
dard quality control practices. A specific number of tests is not tuted.
required, but the fasteners shall be produced by manufacturing
practices and subjected to tests and inspection to assure 13. Specimen Preparation
compliance with the specified requirements. 13.1 Chemical Tests—When required, samples for chemical
12.1.2.2 When specified on the purchase order, not less than analysis shall be taken by drilling, sawing, milling, turning,
one corrosion test to determine freedom from precipitated clipping, or other such methods capable of producing repre-
carbides shall be made to represent each lot. sentative samples.
12.2 Retests: 13.2 Mechanical Tests:
12.2.1 When tested in accordance with the required sam- 13.2.1 Nuts shall be tested in full section.
pling plan, a lot shall be subject to rejection if any of the test 13.2.2 The hardness shall be determined on the top or
specimens fail to meet the applicable test requirements. bottom face of the nut.

4
 F594 − 22
TABLE 2 Mechanical Property RequirementsA
Stainless Alloy Alloy Mechanical Nominal Diam- Proof Stress, Proof Stress, Rockwell
Group ConditionB Property Marking eter, in. Hex Nuts Heavy Hex Nuts Hardness
ksi, min ksi, minC
Austenitic Alloys
AF F594A 1⁄4 to 11⁄2, incl 70 76 B85 max
1 A F594B 1⁄4 to 11⁄2, incl 75 81 B65 to 95, incl
(303, 304, 304L CW1 F594C 1⁄4 to 5⁄8, incl 100 108 B95 to C35, incl
305, 384, CW2 F594D 3⁄4 to 11⁄2, incl 85 92 B80 to C35, incl
XM1, 18–9LW, SH1 F594A 1⁄4 to 5⁄8, incl 120 130 C24 to C36, incl
302HQ, 303Se) SH2 F594B 3⁄4 to 1, incl 110 119 C20 to C32, incl
SH3 F594C 11⁄8 to 11⁄4, incl 100 108 B95 to C30, incl
SH4 F594D 13⁄8 to 11⁄2, incl 85 92 B90 to C28, incl

AF F594E ⁄ to 11⁄2, incl

14 70 76 B85 max
2 A F594F ⁄ to 11⁄2, incl
14 75 81 B65 to 95, incl
(316) CW1 F594G 1⁄4 to 5⁄8, incl 100 108 B95 to C35, incl
316L CW2 F594H 3⁄4 to 11⁄2, incl 85 92 B80 to C35, incl
SH1 F594E 1⁄4 to 5⁄8, incl 120 130 C24 to C36, incl
SH2 F594F 3⁄4 to 1, incl 110 119 C20 to C32, incl
SH3 F594G 11⁄8 to 11⁄4, incl 100 108 B95 to C30, incl
SH4 F594H 13⁄8 to 11⁄2, incl 85 92 B90 to C28, incl

AF F594J 14⁄ to 11⁄2, incl 70 76 B85 max

3 A F594K 14⁄ to 11⁄2, incl 75 81 B65 to 95, incl
(321, 347) CW1 F594L 1⁄4 to 5⁄8, incl 100 108 B95 to C35, incl
CW2 F594M 3⁄4 to 11⁄2, incl 85 92 B80 to C35, incl
SH1 F594J 1⁄4 to 5⁄8, incl 120 130 C24 to C36, incl
SH2 F594K 3⁄4 to 1, incl 110 119 C20 to C32, incl
SH3 F594L 11⁄8 to 11⁄4, incl 100 108 B95 to C30, incl

iTeh Standards
SH4 F594M 13⁄8 to 11⁄2, incl 85 92 B90 to C28, incl
Ferritic Alloys
4 A F594N 1⁄4 to 11⁄2, incl 55 59 85 max
(430, 430F) CW1 F594V 1⁄4 to 5⁄8 , incl 60 65 B75 to 98, incl

5
CW2

H
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F594W

F594P
3⁄4 to 11⁄2, incl

Martensitic Alloys
1⁄4 to 11⁄2, incl
55

100
59

108
B65 to 95, incl

C20 to 30, incl

(410, 416, 416Se) HT
Document PreviewF594R 1⁄4 to 11⁄2, incl 160 173 C34 to 45, incl
6 H F594S 1⁄4 to 11⁄2, incl 125 135 C25 to 32, incl
(431) HT F594T 1⁄4 to 11⁄2 , incl 180 194 C40 to 48, incl
Precipitation Hardening Alloys
7 AH F594U 1⁄4 to 11⁄2, incl 135 146 C28 to 38, incl
(630) ASTM F594-22
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A
Minimum values except where shown as maximum or as a range.
B
Legend of conditions:
A—Machined from annealed or solution annealed stock thus retaining the properties of the original stock; or hot formed and solution annealed.
AF—Annealed after all threading is completed.
AH—Solution annealed and age hardened after forming.
CW—Annealed and cold worked. Sizes 0.75 in. and larger may be hot worked and solution annealed.
H—Hardened and tempered at 1050 °F (566 °C) min.
HT—Hardened and tempered at 525 °F (274 °C) min.
SH—Machined from strain hardened stock.
C
Proof stress values for heavy hex nuts are based on 1.08 times the value for corresponding hex nuts.

13.3 Corrosion Resistance—Test specimens shall be pre- 14.2 Mechanical Tests:

pared in accordance with Practices A262. 14.2.1 The proof load or proof stress shall be determined on
each sample in accordance with Test Methods F606/F606M.
14. Test Methods 14.2.2 The hardness shall be determined in accordance with
14.1 Chemical Analysis—Chemical analysis shall be per- Test Methods F606/F606M at the top or bottom face of the nut.
formed in accordance with Test Methods, Practices, and A minimum of two readings shall be made on each sample,
Terminology A751. each of which shall conform to the specified requirements.