ASTM A194 Grade 7L Heavy Hex Nuts
Heavy hex nuts in ASTM A194 Grade 7L — the low-temperature member of the Grade 7 pair: identical chromium-molybdenum chemistry (AISI 4140/4142 family, C 0.37–0.49%, Cr 0.75–1.20%, Mo 0.15–0.25%) and hardness, with a mandatory Charpy V-notch impact requirement at −150 °F (−101 °C) for low-temperature service with A320 Grade L7 studs.
Last updated: 2026-11
Specifications
Grade 7L answers one question: what happens to a Grade 7 nut when the line runs cold. The chemistry is the same medium-carbon chromium-molybdenum alloy as Grade 7 — carbon 0.37–0.49%, silicon 0.15–0.35%, manganese 0.65–1.10%, phosphorus 0.035% max, sulfur 0.04% max, chromium 0.75–1.20%, molybdenum 0.15–0.25%, the AISI 4140/4142 family — quenched and tempered into the heavy hex form with hardness in the 248–302 BHN band the collected datasheet prints for the style. The "L" adds a single, decisive requirement: Charpy V-notch impact testing at −150 °F (−101 °C), certifying that the nut keeps its toughness where ordinary Grade 7 has no data. It is the nut-side mirror of the B7/B7L stud convention — A194 7L pairs with A320 L7 studs the same way 7 pairs with B7 — so the low-temperature callout travels through the whole bolted joint, not just one component. Use it for cryogenic-adjacent process lines, cold-climate field equipment and any specification that cites impact-tested nuts; note the "L" is a certification requirement, not a different alloy, which is why the two grades cannot be told apart without the test record. The collected datasheet's metric proof-load ladder prints the M6 heavy hex value at 29.2 kN with the larger sizes truncated in the extract — per-size proof loads are confirmed at quotation from the current edition.
| Standard | ASTM A194 Grade 7L — heavy hex nuts, low-temperature impact-tested |
|---|---|
| Chemistry (weight %) | C 0.37–0.49; Si 0.15–0.35; Mn 0.65–1.10; P 0.035 max; S 0.04 max; Cr 0.75–1.20; Mo 0.15–0.25 (AISI 4140/4142 family) |
| Hardness | 248–302 BHN (heavy hex style, as printed by the collected datasheet) |
| Low-temperature requirement | Charpy V-notch impact testing at −150 °F (−101 °C) — the only delta from Grade 7 |
| Stud pairing convention | A194 Gr. 7L with A320 Gr. L7 studs, mirroring the Gr. 7 / B7 convention |
| Proof load | Metric ladder per size; M6 heavy hex 29.2 kN printed (higher sizes confirmed at quotation from the current edition) |
| Service intent | High-pressure service at low temperature; nuts for A320 L7 stud bolts |
Materials
- Medium-carbon Cr-Mo alloy steel (AISI 4140/4142 family), quenched and tempered, impact-tested at −150 °F
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 7L 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
Is Grade 7L a different steel from Grade 7?
No — the chemistry, heavy hex form and hardness band are identical, and that is easy to verify against a mill certificate. The difference is the certification: 7L carries mandatory Charpy V-notch impact testing at −150 °F (−101 °C), so it arrives with an impact record proving toughness at temperature. That is why the grades are not interchangeable in the other direction either: a plain Grade 7 nut has no impact data, however sound its chemistry.
What should an RFQ for A194 Gr. 7L nuts state?
The grade callout (ASTM A194 Grade 7L, heavy hex), thread size and series, the mating stud grade (A320 L7 by convention), finish or lubrication if the specification carries one, quantity per size, and the certificate scope — the impact test record is the reason the grade exists, so state explicitly that Charpy results at −150 °F accompany the shipment. Proof loads for the specific sizes are confirmed with the quotation.
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. Confirm the exact schedule against quantity and size mix at quotation.
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