ASTM F594 Nuts Specification

Stainless steel Square Nuts & Hex Nuts intended for service applications requiring general corrosion resistance

ASTM F594 Hex Nut, Heavy hex Nut, Square Nuts, Hexagon High Nuts, Slotted Nuts

ASTM F594 specification covers the requirements for Stainless steel Square Nuts & Hex Nuts 1/4" to 1 1/2 inch inclusive, in nominal diameter in a number of alloys in common use and intended for service applications requiring general corrosion resistance. Seven groups of stainless steel alloys are covered, including ten austenitic, two ferritic, four martensitic, and one precipitation hardening. Suitable bolts, hex cap screws, and studs for use with nuts included in this specification are covered by Specification ASTM F593. Unless otherwise specified, all bolts, hex cap screws, and studs used with these nuts shall conform to the requirements of Specification ASTM F593 and shall be of the same alloy group.

ASTM F594 Scope

Group AlloysA ConditionB Optional Conditions (must be specified) Alloy Type
1 304, 305, 384, 304 L, (CW) cold workedC AF, A, SH Austenitic
18-9LW, 302HQ, 304J3D
2 316, 316 L CW) cold workedC
3 321, 347 (CW) cold workedC
4 430E (CW) cold workedC A Ferritic
5 410F (H) hardened and tempered HT Martensitic
6 431 (H) hardened and tempered
7 630 (AH) age hardened none Precipitation Hardening
  • A) Unless otherwise specified on the inquiry and order, the choice of an alloy from within a group shall be at the discretion of the fastener manufacturer.
  • (B) See 4.2 for options.
  • (C) Sizes 0.75 in. and larger may be hot worked and solution annealed, provided the bolts comply with the cold worked (CW) mechanical property requirements.
  • (D) When approved by the purchaser, Alloys 303, 303Se, or XM1 may be furnished.
  • (E) When approved by the purchaser, Alloy 430F may be furnished.
  • (F) When approved by the purchaser, Alloys 416 or 416Se may be furnished.
  • A - Machined from annealed or solution-annealed stock thus retaining the properties of the original material; or hot-formed and solution annealed.
  • properties of the original material; or hot-formed and solution annealed.
  • AF - Headed and rolled from annealed stock and then reannealed.
  • AH - Solution-annealed and age-hardened after forming.
  • CW - Headed and rolled from annealed stock thus acquiring a degree of cold work. Sizes 0.75 in. and larger may be hot-worked and solution-annealed.
  • H - Hardened and tempered at 1050°F (565°C) minimum.
  • HT - Hardened and tempered at 525°F (274°C) minimum.
  • SH - Machined from strain-hardened stock or cold-worked to develop the specific properties.

ASTM F594 Chemical Composition

Alloy Group Alloys
1 304, 304 L, 305, 384, 18-9LW, 302HQ, 304J3A
2 316, 316 L
3 321, 347
4 430B
5 410C
6 431
7 630
  • (A) When approved by the purchaser, Alloys 303, 303Se, or XM1 may be furnished.
  • (B) When approved by the purchaser, Alloy 430F may be furnished.
  • (C) When approved by the purchaser, Alloys 416 or 416Se may be furnished.

ASTM F594 Chemical Requirements

Alloy Group UNS Designation Alloy C Mn P S Si Cr Ni Cu Mo Others
ASTM F594 Alloy Group 1 S30300 303 0.15 2.00 0.20 0.15 min 1.00 17.0 to 19.0 8.0 to 10.0 . . . 0.60 maxA . . .
S30323 303 Se 0.15 2.00 0.20 0.060 1.00 17.0 to 19.0 8.0 to 10.0 . . . . . . Se 0.15 min
S30400 304 0.08 2.00 0.045 0.030 1.00 18.0 to 20.0 8.0 to 10.5 1.00 . . . . . .
S30403 304 L 0.03 2.00 0.045 0.030 1.00 18.0 to 20.0 8.0 to 12.0 1.00 . . . . . .
S30500 305 0.12 2.00 0.045 0.030 1.00 17.0 to 19.0 10.5 to 13.0 1.00 . . . . . .
S38400 384 0.08 2.00 0.045 0.030 1.00 15.0 to 17.0 17.0 to 19.0 . . . 0.50 maxA . . .
S20300 XM1 0.08 5.0 to 6.5 0.040 0.18 to 0.35 1.00 16.0 to 18.0 5.0 to  6.5 1.75 to 2.25 . . . . . .
S30430 18-9LW 0.10 2.00 0.045 0.030 1.00 17.0 to 19.0 8.0 to 10.0 3.0 to 4.0 . . . . . .
S30433 302HQ 0.03 2.00 0.045 0.030 1.00 17.0 to 19.0 8.0 to 10.0 3.0 to 4.0 . . . . . .
. . . 304J3B 0.08 2.00 0.045 0.030 1.00 17.0 to 19.0 8.0 to 10.5 1.00 to 3.00 . . . . . .
ASTM F594 Alloy Group 2 S31600 316 0.08 2.00 0.045 0.030 1.00 16.0 to 18.0 10.0 to 14.0 . . . 2.00 to 3.00 . . .
S31603 316 L 0.03 2.00 0.045 0.030 1.00 16.0 to 18.0 10.0 to 14.0 . . . 2.00 to 3.00 . . .
ASTM F594 Alloy Group 3 S32100 321 0.08 2.00 0.045 0.030 1.00 17.0 to 19.0 9.0 to 12.0 . . . . . . Ti   5× C min
S34700 347 0.08 2.00 0.045 0.030 1.00 17.0 to 19.0 9.0 to 13.0 . . . . . . Cb+Ta  10 × C min
ASTM F594 Alloy Group 4 S43000 430 0.12 1 0.04 0.030  1 16.0 to 18.0 . . . . . .  0.60 maxA . . .
S43020 430F 0.12 1.25 0.06 0.15 min 1 16.0 to 18.0 . . . . . . . . . . . .
ASTM F594 Alloy Group 5 S41000 410 0.15 1 0.04 0.03 1 11.5 to 13.5 . . . . . .  0.60 maxA    Se 0.15 min
S41600 416 0.15 1.25 0.06 0.15 min 1 12.0 to 14.0 . . . . . . . . . . . .
S41623 416Se 0.15 1.25 0.06 0.06 1 12.0 to 14.0 . . . . . . . . . . . .
ASTM F594 Alloy Group 6 S4310 431 0.20 1.00 0.040 0.030 1.00 15.0 to 17.0 1.25 to 2.50 . . . . . . . . .
ASTM F594 Alloy Group 7 S17400 630 0.07 1.00 0.040 0.030 1.00 15.0 to 17.5 3.0 to 5.0 3.0 to 5.0 . . . Cb+Ta  0.15-0.45
  • (A) At manufacturer's option, determined only when intentionally added.
  • (B) 304J3 from JIS Standard G4309.

ASTM F594 Mechanical Property Requirements

Stainless Alloy Group ConditionB Alloy Mechanical Property Marking Nominal Diam- eter, in. Proof Stress, Hex Nuts ksi, min Proof Stress, Heavy Hex Nuts ksi, minC Rockwell Hardness
ASTM F594 Alloy Group 1
 (303, 304, 304L305, 384,XM1, 18-9LW,302HQ, 303Se)
AF F594A 1/4 to 11/2 , incl 70 76 B85 max
A F594B 1/4 to 11/2 , incl 75 81 B65 to 95, incl
CW1 F594C 1/4 to 5/8 , incl 100 108 B95 to C35, incl
CW2 F594D 3/4 to 11/2 , incl 85 92 B80 to C35, incl
SH1 F594A 1/4 to 5/8 , incl 120 130 C24 to C36, incl
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
ASTM F594 Alloy Group 2
(316)316L
AF F594E 1/4 to 11/2 , incl 70 76 B85 max
A F594F 1/4 to 11/2 , incl 75 81 B65 to 95, incl
CW1 F594G 1/4 to 5/8 , incl 100 108 B95 to C35, incl
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
ASTM F594 Alloy Group 3 
(321, 347)
AF F594J 1/4 to 11/2 , incl 70 76 B85 max
A F594K 1/4 to 11/2 , incl 75 81 B65 to 95, incl
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
SH4 F594M 13/8 to 11/2 , incl 85 92 B90 to C28, incl
ASTM F594 Alloy Group 4
(430, 430F)
A F594N 1/4 to 11/2 , incl 55 59 85 max
CW1 F594V 1/4 to 5/8 , incl 60 65 B75 to 98, incl
CW2 F594W 3/4 to 11/2 , incl 55 59 B65 to 95, incl
ASTM F594 Alloy Group 5
 (410, 416, 416Se)
F594P  1/4 to 11/2 , incl  100  108  C20 to 30, incl 
HT F594R 1/4 to 11/2 , incl 160 173 C34 to 45, incl
ASTM F594 Alloy Group 6
 (431)
F594S  1/4 to 11/2, incl  125  135  C25 to 32, incl 
HT F594T 1/4 to 11/2, incl 180 194 C40 to 48, incl
ASTM F594 Alloy Group 7
(630)
AH F594U 1/4 to 11/2 , incl 135 146 C28 to 38, incl
  • (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.

ASTM F594 Mechanical Test Requirements on Nuts

Product Proof Stress, psi Tests Conducted using Full Size Product
Hardness Proof Load
Jam, slotted, 
 castle nuts
all A B
All other nuts up to 120 000 A A
Over 120 000 option AA option B
  • (A) Denotes mandatory tests; where options are given, all the tests under an option shall be performed. Option B tests should be made whenever feasible. Option B is the referee test in case of arbitration.
  • (B) Tests that are not mandatory.

ASTM F594 Tensile Stress Areas and Threads per Inch

Nominal Size, in. (D) Coarse Threads-UNC Fine Threads-UNF 8 Thread Series-8 UN
Threads/ in. Stress Area,A in. 2 Threads/ in. Stress Area,A in. 2 Threads/ in. Stress Area,A in. 2
1/4 (0.250) 20 0.0318 28 0.0364 . . . . . .
5/16 (0.3125) 18 0.0524 24 0.0580 . . . . . .
3/8 (0.375) 16 0.0775 24 0.0878 . . . . . .
7/16 (0.4375) 14 0.1063 20 0.1187 . . . . . .
1/2 (0.500) 13 0.1419 20 0.1599 . . . . . .
9/16 (0.5625) 12 0.1820 18 0.2030 . . . . . .
5/8 (0.625) 11 0.2260 18 0.2560 . . . . . .
3/4 (0.750) 10 0.3340 16 0.3730 . . . . . .
7/8 (0.875) 9 0.4620 14 0.5090 . . . . . .
1.000 . . . 8 0.6060 12 0.6630 . . . . . .
11/8 (1.125) 7 0.7630 12 0.8560 8 0.790
11/4 (1.250) 7 0.9690 12 1.0730 8 1.000
13/8 (1.375) 6 1.1550 12 1.3150 8 1.233
11/2 (1.500) 6 1.4050 12 1.5810 8 1.492
  • (A) Tensile stress areas are computed using the following formula:
  • As = 0.7854 [D - 0.9743/n]2
  • where:
  • As = tensile stress area, in.2,
  • D = nominal size (basic major diameter), in., and
  • n = number of threads per inch.

ASTM F594 Heat Treatment

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ASTM F594 Bolting Surface Treatment Specifications

ASTM F594 Bolting Components Marking

Product Shall be Marked with our manufacturing trade mark "TorqBolt" or "TB" along with the designated Grade.
Grade and manufacturer’s identification symbols shall be applied to one end of studs and to the heads of bolts and screws of all sizes. (If the available area is inadequate, the grade symbol may be marked on one end and the manufacturer’s identification symbol marked on the other end.) For bolts and screws smaller than 1⁄4 in. [6 mm] in diameter and studs smaller than 3⁄8 in. [10 mm] in diameter and for 1⁄4 in. [6 mm] in diameter studs requiring more than a total of three symbols, the marking shall be a matter of agreement between the purchaser and the manufacturer.

ASME Dimensional Standards

B18.2.2 Imperial Square, Hex, Heavy Hex, Lock, Heavy Hex Lock Nuts

ASTM F594 Bolting Certifications

  • EN 10204 3.1
  • EN 10204 3.2
  • PED 2014/68/EC
  • MERKBLATT AD 2000 W2/W7/W10
  • API 20 E BSL 1/ BSL 2
  • NACE MR 0175
  • NACE MR 0103

ASTM F594 Testing Standards

ASME B1.1 Unified Inch Screw Threads (UN and UNR Thread Form)
ASME B1.3 Screw Thread Gaging System for Dimensional Acceptability - Inch Screw Threads (IN, UNR, and UNJ)
ASME B1.13M Metric Screw Threads - M Profile
ASME B1.21M Metric Screw Threads - MJ Profile
ASME B1.2 Gauges & gauging for Unified Screw Threads(Imperial)

ASME Threading Specifications

ASME B1.1 Unified Inch Screw Threads (UN and UNR Thread Form)
ASME B1.3 Screw Thread Gaging System for Dimensional Acceptability - Inch Screw Threads (IN, UNR, and UNJ)

ASTM F594 Supplementary Requirements

S1 Shipment Lot Testing
S2 Additional Tests
S3 Source Inspection
S4 Alloy Control
S5 Heat Control
S6 Permeability