ASTM A563 Carbon and Alloy Steel Nuts (Grades A, B, C, D, DH, DH3)
The nut specification for carbon and alloy steel bolting: Grade A for A307, Grade B for cast-iron flanges, C and D for 105 to 120 ksi bolts, and DH and DH3 heat treated for A325, A490, A354 and Grade 8 — with proof stress by grade and style.
What A563 nuts is.
ASTM A563 covers the nuts that go with carbon and alloy steel bolts. Each grade is matched to a bolt strength by its proof stress: Grade A (90 to 100 ksi) for A307 and Grade 2 bolts; Grade B (105 to 133 ksi) for flanged joints; Grades C and D (130 to 150 ksi) for 120 ksi bolts; Grade DH (150 to 175 ksi, quenched and tempered) for A325, A490, A354 BD and Grade 8; and DH3, the weathering-steel version. Heavy hex nuts carry a higher proof stress than finished hex of the same grade because of their thicker section.
We machine A563 nuts in every grade and style, including the large and special sizes stock does not cover, and supply them plain, zinc plated or hot-dip galvanized and overtapped to suit coated bolts.
Chemical composition.
| Element | Grades A, B, C (and 8S) | Grade DH (and 10S) | Grade D |
|---|---|---|---|
| Carbon, max | 0.55 | 0.20–0.55 | 0.55 |
| Manganese | — | 0.60 min | 0.30 min |
| Phosphorus, max | 0.12 | 0.04 | 0.04 |
| Sulfur, max | 0.15 | 0.05 | 0.05 |
Values per ASTM A563/A563M-21 Table 1 (verified against the specification). Confirm the edition called out on your purchase order with our estimating team. Grades C3 and DH3 (weathering steel) have their own columns in the same table.
Mechanical properties.
| Grade · style · size | Proof stress, plain (ksi) | Proof stress, zinc coated (ksi) | Hardness, min | Hardness, max | — |
|---|---|---|---|---|---|
| A · hex · ¼–4 | 90 | 68 | 116 HBW / B68 | 302 HBW / C32 | |
| A · heavy hex · ¼–4 | 100 | 75 | 116 HBW / B68 | 302 HBW / C32 | |
| B · heavy hex · ¼–1 | 133 | 100 | 121 HBW / B69 | 302 HBW / C32 | |
| B · heavy hex · 1⅛–1½ | 116 | 87 | 121 HBW / B69 | 302 HBW / C32 | |
| C, C3 · heavy hex · ¼–4 | 144 | 144 | 143 HBW / B78 | 352 HBW / C38 | |
| D · heavy hex · ¼–4 | 150 | 150 | 159 HBW / B84 | 352 HBW / C38 | |
| DH, DH3 · heavy hex · ¼–4 | 175 | 150 | 248 HBW / C24 | 352 HBW / C38 | |
| DH · hex · ¼–4 | 150 | 150 | 248 HBW / C24 | 352 HBW / C38 |
Values per ASTM A563/A563M-21 Table 2 (verified against the specification). Confirm the edition called out on your purchase order with our estimating team. Zinc-coated nuts of Grades A, B and DH carry the lower proof stress shown; fine-thread nuts are listed separately in the specification.
Specifications that apply.
How A563 nuts ships from Houston.
- Hex and heavy hex bolts and cap screws
- Studs and threaded rod
- Nuts and washers to match
- Machined specials to drawing
A563 nuts fasteners we make.
Every item is manufactured to your drawing or standard in A563 nuts, imperial or metric, with an EN 10204 3.1 certificate.
Matching the nut to the bolt
A nut must be able to develop the full strength of the bolt without stripping, so its proof stress is set above the bolt's tensile strength. Grade A at 90 to 100 ksi covers 60 ksi A307 bolts with margin; Grade DH at 175 ksi covers 150 ksi A490 and Grade 8. Heavy hex nuts are thicker and wider than finished hex, which is why they carry the higher proof stress and why structural and high-strength bolting specifies them. When a nut is galvanized it is tapped oversize, and the specification allows a lower proof stress for the coated nut to account for the reduced thread engagement.
Testing, certification and marking
- Proof load and hardness per lot to ASTM F606
- Grade mark (A, B, C, D, DH, DH3) and manufacturer's identification on the nut
- Certificate of conformance or test report with heat number
- Overtap size and lubricant reported on galvanized DH nuts
Recent A563 nuts jobs.
ASTM A194 Grade 2H
The standard heavy hex nut for A193 B7 studs — quenched and tempered carbon steel, 175 ksi proof load, 24 to 35 HRC.
ASTM F594ASTM F594 Stainless Steel Nuts
The stainless nut specification: the same alloy groups and conditions as F593 bolts, with proof stress from 70 ksi annealed to 120 ksi strain hardened for austenitic grades and 160 ksi for hardened 410.
ASTM F3125/F3125M Grade A325 · Type 1 and Type 3ASTM F3125 Grade A325 Structural Bolts (120 ksi)
The structural steel connection bolt: heavy hex head, 120 ksi tensile, ½ to 1½ in., quenched and tempered, with the twist-off F1852 and metric A325M variants in the same specification.