ASTM A563
ASTM A563 Hex Nut Grade O,A,B, C,D.

ASTM A563 Grades
A | Carbon steel, hex or heavy hex |
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B | Carbon steel, hex or heavy hex |
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C | Carbon steel, quenched and tempered, heavy hex |
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D | Carbon steel, quenched and tempered, heavy hex |
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DH | Carbon steel, quenched and tempered, heavy hex |
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C3 | Weathering steel, quenched and tempered, heavy hex |
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DH3 | Weathering steel, quenched and tempered, heavy hex |
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ASTM A563 Mechanical Properties
Grade | Style | Size, in. | Proof Load, ksi | Hardness, HBN |
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Plain | Galvanized |
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A | Hex | 1/4 – 1-1/2 | 90 | 68 | 116 – 302 |
Heavy Hex | 1/4 – 4 | 100 | 75 | 116 – 302 |
B | Heavy Hex | 1/4 – 1 | 133 | 100 | 121 – 302 |
Heavy Hex | 1-1/8 – 1-1/2 | 116 | 87 | 121 – 302 |
C / C3 | Heavy Hex | 1/4 – 4 | 144 | 144 | 143 – 352 |
D | Heavy Hex | 1/4 – 4 | 150 | 150 | 248 – 352 |
DH / DH3 | Heavy Hex | 1/4 – 4 | 175 | 150 | 248 – 352 |
For UNC, 8UN, 6UN, and Coarse Pitch Threads |
ASTM A563 Chemical Properties
Element | Grades O, A, B, C | D** | DH** |
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Carbon | 0.55% max | 0.55% max | 0.20 – 0.55% |
Manganese, min | | 0.30% | 0.60% |
Phosphorus, max | 0.12% | 0.04% | 0.04% |
Sulfur, max | 0.15%* | 0.05% | 0.05% |
* For grades O, A and B a sulfur content of 0.23% max is acceptable with the purchasers approval |
** For grades D and DH a sulfur content of 0.05 – 0.15% is acceptable provided the manganese is 1.35% min |
Element | Classes for Grade C3* | DH3 |
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A | B | C | D | E | F | N |
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Carbon | 0.33 – 0.40% | 0.38 – 0.48% | 0.15 – 0.25% | 0.15 – 0.25% | 0.20 – 0.25% | 0.20 – 0.25% | | 0.20 – 0.53% |
Manganese | 0.90 – 1.20% | 0.70 – 0.90% | 0.80 – 1.35% | 0.40 – 1.20% | 0.60 – 1.00% | 0.90 – 1.20% | | 0.40% min |
Phosphorus | 0.040% max | 0.06 – 0.12% | 0.035% max | 0.040% max | 0.040% max | 0.040% max | 0.07 – 0.15% | 0.046% max |
Sulfur, max | 0.050% | 0.050% | 0.040% | 0.050% | 0.040% | 0.040% | 0.050% | 0.050% |
Silicon | 0.15 – 0.35% | 0.30 – 0.50% | 0.15 – 0.35% | 0.25 – 0.50% | 0.15 – 0.35% | 0.15 – 0.35% | 0.20 – 0.90% | |
Copper | 0.25 – 0.45% | 0.20 – 0.40% | 0.20 – 0.50% | 0.30 – 0.50% | 0.30 – 0.60% | 0.20 – 0.40% | 0.25 – 0.55% | 0.20% min |
Nickel | 0.25 – 0.45% | 0.50 – 0.80% | 0.25 – 0.50% | 0.50 – 0.80% | 0.30 – 0.60% | 0.20 – 0.40% | 1.00% max | 0.20% min** |
Chromium | 0.45 – 0.65% | 0.50 – 0.75% | 0.30 – 0.50% | 0.50 – 1.00% | 0.60 – 0.90% | 0.45 – 0.65% | 0.30 – 1.25% | 0.45% min |
Vanadium | | | 0.020% min | | | | | |
Molybdenum | | 0.06% max | | 0.10% max | | | | 0.15% min** |
Titanium | | | | 0.05% max | | | | |
* Selection of a class shall be at the option of the manufacturer |
** Nickel or Molybdenum may be used. |
ASTM A563 Grade Identification Markings
Grade Identification Marking | Specification | Material | Nominal Size, In. | Proof Load Stress, ksi | Hardness Rockwell | See Note |
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Min | Max |
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 | ASTM A563 Grade O | Carbon Steel | 1/4 – 1-1/2 | 69 | B55 | C32 | 2,3 |
ASTM A563 Grade A | Carbon Steel | 1/4 – 1-1/2 | 90 | B68 | C32 | 2,3 |
ASTM A563 Grade B | Carbon Steel | 1/4 – 1 | 120 | B69 | C32 | 2,3 |
>1 – 1-1/2 | 105 |
 | ASTM A563 Grade C | Carbon Steel, may be Quenched and Tempered | 1/4 – 4 | 144 | B78 | C38 | 4 |
 | ASTM A563 Grade C3 | Atmospheric Corrosion Resistant Steel, may be Quenched and Tempered | 1/4 – 4 | 144 | B78 | 38 | 4,6 |
 | ASTM A563 Grade D | Carbon Steel, may be Quenched and Tempered | 1/4 – 4 | 150 | B84 | C38 | 5 |
 | ASTM A563 Grade DH | Carbon Steel, Quenched and Tempered | 1/4 – 4 | 175 | C24 | C38 | 5 |
 | ASTM A563 Grade DH3 | Atmospheric Corrosion Resistant Steel, Quenched and Tempered | 1/4 – 4 | 175 | C24 | C38 | 4,6 |
NOTES:- In addition to the indicated grade marking, all grades, except A563 grades O, A, and B, must be marked for manufacturer identification.
- Nuts are not required to be marked unless specified by the purchaser. When marked, the identification marking shall be the grade letter O, A, or B.
- Properties shown are those of nonplated or noncoated coarse thread nuts.
- Properties shown are those of coarse thread heavy hex nuts.
- Properties shown are those of coarse thread heavy hex nuts. Other nuts styles and fine threads may apply.
- The nut manufacturer, at his option, may add other markings to indicate the use of atmospheric corrosion resistant steel.
Inch Fastener Standards. 7th ed. Cleveland: Industrial Fasteners Institute, 2003. n-80-n-81. |
Thread Dimensions and Oversizing Allowances
For Nuts: Hot Dipped Galvanized per Specification F2329
Nominal Nut Size, in. and Pitch | Diametral Allowance, in. | Pitch Diameter |
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Min | Max |
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0.250 – 20 | 0.016 | 0.2335 | 0.2384 |
0.312 – 18 | 0.017 | 0.2934 | 0.2987 |
0.375 – 16 | 0.017 | 0.3514 | 0.3571 |
0.437 – 14 | 0.018 | 0.4091 | 0.4152 |
0.500 – 13 | 0.018 | 0.4680 | 0.4745 |
0.562 – 12 | 0.020 | 0.5284 | 0.5352 |
0.625 – 11 | 0.020 | 0.5860 | 0.5932 |
0.750 – 10 | 0.020 | 0.7050 | 0.7127 |
0.875 – 9 | 0.022 | 0.8248 | 0.8330 |
1.000 – 8 | 0.024 | 0.9428 | 0.9516 |
1.125 – 8 | 0.024 | 1.0678 | 1.0768 |
1.125 – 7 | 0.024 | 1.0562 | 1.0656 |
1.250 – 8 | 0.024 | 1.1928 | 1.2020 |
1.250 – 7 | 0.024 | 1.1812 | 1.1908 |
1.375 – 8 | 0.027 | 1.3208 | 1.3301 |
1.375 – 6 | 0.027 | 1.2937 | 1.3041 |
1.500 – 8 | 0.027 | 1.4458 | 1.4553 |
1.500 – 6 | 0.027 | 1.4187 | 1.4292 |
1.750 – 5 | 0.050 | 1.6701 | 1.6817 |
2.000 – 4.5 | 0.050 | 1.9057 | 1.9181 |
2.250 – 4.5 | 0.050 | 2.1557 | 2.1683 |
2.500 – 4 | 0.050 | 2.3876 | 2.4011 |
2.750 – 4 | 0.050 | 2.6376 | 2.6513 |
3.000 – 4 | 0.050 | 2.8876 | 2.9015 |
3.250 – 4 | 0.050 | 3.1376 | 3.1517 |
3.500 – 4 | 0.050 | 3.3876 | 3.4019 |
3.750 – 4 | 0.050 | 3.6376 | 3.6521 |
4.000 – 4 | 0.050 | 3.8876 | 3.9023 |
The ASTM A563 determination covers the synthetic and mechanical prerequisites for carbon and compound steel nuts utilized on screws, studs, and remotely Threaded Fasteners. The diagrams beneath address over tapping remittances for hot-plunge aroused nuts, grade stamping prerequisites, and mechanical necessities. For data on reasonable nuts for different grades of fasteners.
As indicated by the A563 determination, “The prerequisites for any grade of nut may, at the provider’s choice, and with notice to the buyer, be satisfied by outfitting nuts of one of the more grounded grades determined thus except if such a replacement is banished in the request and buy request”. This is significant on the grounds that some nut grades are not promptly accessible in specific sizes and wraps up. Furthermore, the determination considers the replacement of ASTM A194 grade 2H nuts in lieu of A563 grade DH nuts because of the absence of accessibility of grade DH nuts in ostensible sizes 3/4″ and bigger.