ASTM A194 Grade 6 Heavy Hex Nuts
ASTM A194 Grade 6 heavy hex nuts — quenched and tempered Type 410 martensitic stainless steel (Cr 11.5–13.5%, UNS S41000), 228–271 HB hardness (Rockwell C 20–28), with the full A194-11 proof-load ladder from 4,770 lbf at 1/4" to 223,800 lbf at 1-1/2" heavy hex (150,000 psi proof stress) and large heavy hex through 2-3/4".
Last updated: 2026-11
Specifications
Grade 6 is the martensitic stainless member of ASTM A194's ferritic-stainless group (the collected specification page groups it as "Ferritic Grades — 2H & 6"): a Type 410 chemistry (UNS S41000, 11.5–13.5% chromium) quenched and tempered so the nut combines the corrosion behaviour of a straight chromium stainless with hardness in the 228–271 Brinell band (Rockwell C 20–28). It is the stainless counterpart to the carbon-steel 2H rather than an austenitic grade like 8 or 8M — expect less low-temperature toughness and less general corrosion resistance than the 300-series grades, but a heat-treated martensitic structure the austenitic grades do not offer. The A194-11 proof-load table runs the full inch ladder from 1/4 through 1-1/2, based on a 150,000 psi proof stress in heavy hex (135,000 psi in the hex pattern), with the large heavy hex ladder to 2-3/4" carrying 814,500 lbf at 2-3/4. Proof loads are qualification figures, not design loads, and jam nuts are tested at 46% of the tabulated load per the standard's own note.
| Standard | ASTM A194 — Grade 6 (heavy hex pattern; scope 1/4"–4" nominal) |
|---|---|
| Material | Type 410 martensitic stainless steel (UNS S41000), quenched and tempered — grouped under the specification's "Ferritic Grades" with 2H |
| Chemistry (A194-11 Table 1) | C max 0.15%, Mn max 1.00%, P max 0.040%, S max 0.030%, Si max 1.00%, Cr 11.5–13.5% |
| Hardness (A194-11 Table 2) | Completed nuts: Brinell 228–271, Rockwell C 20–28 |
| Proof-load basis | Heavy hex 150,000 psi; hex pattern 135,000 psi (Table 3 stress-area basis) |
| Proof load, sampled sizes (heavy hex) | 1/4" → 4,770 lbf; 1/2" → 21,280 lbf; 3/4" → 50,100 lbf; 1" → 90,900 lbf; 1-1/2" → 223,800 lbf (full ladder table below) |
| Large heavy hex (Table 10) | 1-5/8" → 267,000 lbf through 2-3/4" → 814,500 lbf (full ladder table below) |
| Jam nuts | Proof load 46% of the tabulated load, per the standard's note |
| Design note | Proof loads are not design loads (A194-11 note 1) |
| Nominal size | Threads per inch | Stress area (in²) | Proof load, heavy hex (lbf) | Proof load, hex (lbf) |
|---|---|---|---|---|
| 1/4 | 20 | 0.0316 | 4770 | 4300 |
| 5/16 | 18 | 0.0524 | 7860 | 7070 |
| 3/8 | 16 | 0.0774 | 11620 | 10460 |
| 7/16 | 14 | 0.1063 | 15940 | 14350 |
| 1/2 | 13 | 0.1419 | 21280 | 19160 |
| 9/16 | 12 | 0.182 | 27300 | 24570 |
| 5/8 | 11 | 0.226 | 33900 | 30510 |
| 3/4 | 10 | 0.334 | 50100 | 45090 |
| 7/8 | 9 | 0.462 | 69300 | 62370 |
| 1 | 8 | 0.606 | 90900 | 81810 |
| 1-1/8 | 8 | 0.79 | 118500 | 106700 |
| 1-1/4 | 8 | 1 | 150000 | 135000 |
| 1-3/8 | 8 | 1.233 | 185000 | 166500 |
| 1-1/2 | 8 | 1.492 | 223800 | 201400 |
| Nominal size | Threads per inch | Stress area (in²) | Proof load, grade 6 heavy hex (lbf) |
|---|---|---|---|
| 1-5/8 | 8 | 1.78 | 267000 |
| 1-3/4 | 8 | 2.08 | 312000 |
| 1-7/8 | 8 | 2.41 | 361500 |
| 2 | 8 | 2.77 | 415500 |
| 2-1/4 | 8 | 3.56 | 534000 |
| 2-1/2 | 8 | 4.44 | 666000 |
| 2-3/4 | 8 | 5.43 | 814500 |
Materials
- Type 410 martensitic stainless steel (UNS S41000), quenched and tempered
Ordering & documentation
Documents
Shipments are backed by Mill Test Certificate (MTC), Dimensional Report, Salt Spray Test Report on request, with full batch traceability from raw material to finished product. Quality management follows the owner-confirmed compliance list: ISO 9001:2015, RoHS, REACH. Exact document sets are confirmed on the order.
Quotation
- The fastener family (ASTM A194 Grade 6 Heavy Hex Nuts) plus the standard designation from your drawing — DIN / ISO / JIS / ASTM / ANSI, or a drawing for custom parts.
- Size (diameter and length), thread type (metric or inch), property class or grade, and coating or finish.
- Quantity per size and your target delivery date.
- Destination country, and any required documents (for example a mill test certificate) so the quote includes them.
Sample & supply
Minimum order quantity is 10,000 pieces. Stock items run 3–7 days. Quantities or variants outside the standard range are confirmed at quotation.
Storage & shipping
Parts are packed for export and shipped factory-direct to buyers in Europe, Asia, the Americas and the Middle East. Store fasteners dry and protected until installation, and keep coated parts in their packaging until use; specific packing and preservation requirements can be stated on the order and confirmed at quotation.
Frequently asked questions
Grade 6 or Grade 8 — which stainless A194 nut for my service?
They are different stainless families, not two strength levels of one. Grade 6 is martensitic (Type 410, 11.5–13.5% chromium, quenched and tempered to 228–271 HB), so it can be heat-treated to a hard, strong structure and suits high-pressure/high-temperature service where the carbon-steel grades would corrode. Grade 8 is austenitic (Type 304 chemistry, 18–20% chromium plus 8–11% nickel, 126–300 HB), with markedly better general corrosion resistance and low-temperature toughness but a much lower proof-load ladder. Where chloride pitting governs, move to 8M (316 chemistry) instead.
Why does the Grade 6 proof ladder read 150,000 psi when Grade 2H heavy hex reads 175,000 psi?
Each grade-and-pattern column of the A194-11 table carries its own proof stress: Grade 2H heavy hex is tabulated at 175,000 psi, Grade 6 heavy hex at 150,000 psi, Grade 6 hex at 135,000 psi, and the austenitic Grade 8s at 80,000/75,000 psi. The tabulated proof load is the stress times the thread stress area for the size, which is why the loads step with size at the same grade. Order by the designation the engineer of record called out rather than by converting one grade into another.
What is the MOQ and lead time for this nut type?
The minimum order quantity is 10,000 pieces. Stock items ship in 3–7 days; non-stock items are confirmed at quotation. Common diameters in this nut type are widely stocked; confirm the exact schedule against quantity and size mix at quotation.
What should an RFQ for this nut type state?
State the standard designation (for example DIN 985 or DIN 6923), nominal thread size and pitch (metric coarse unless fine pitch is required), material and strength pairing with the mating bolt, finish (plain, zinc, or hot-dip galvanized where compatible), required certificates such as a mill test report per EN 10204 3.1, and quantity per size — plus destination country.
Request a Quote
Get factory-direct pricing from the manufacturer.
What to include in your inquiry
- ✓ Standard and property class (e.g. DIN 912, ISO 4762, class 8.8) — or a drawing for custom parts.
- ✓ Sizes, lengths and thread type (metric or inch).
- ✓ Quantity per size and your target delivery date.
- ✓ Destination country, plus any coating or finish requirement.
- ✓ Any documents you need with the shipment (e.g. mill test certificate) so the quote includes them.
- ✓ Your inquiry goes straight to the factory team by email and gets a reply within 24 hours.
- ✓ Factory-direct pricing
- ✓ Standard and custom specifications
- ✓ Factory-direct export to buyers in Europe, Asia, the Americas and the Middle East
- ✓ Full fastener family support