ASTM A194
Grade 4
Carbon Steel Hex Nuts
Why Choose Grade 4 Over Grade 2
Grade 4 occupies a specific niche in the ASTM A194 lineup — a medium carbon steel, quenched and tempered to a higher mechanical property level than Grade 2, without requiring the chromium-molybdenum alloying that Grade 2’s alloy-steel variant or the higher B16/Grade 7 studs typically call for. It’s a genuine, real strength increase achieved through carbon content and heat treatment control rather than alloy chemistry.
That makes Grade 4 the right call specifically when a project genuinely needs strength above Grade 2’s range, but the service conditions don’t demand the elevated-temperature creep resistance or specific alloy composition that would otherwise justify moving to a chromium-molybdenum grade. For general structural and mechanical bolting operating at ambient-to-moderate temperature, that’s a real, cost-relevant distinction — you get meaningfully more strength without paying for alloy content the application doesn’t actually use.
Grade 4 is less commonly stocked than Grade 2 or Grade 2H, simply because most projects needing higher strength than Grade 2 either specify an alloy steel grade directly (when elevated temperature service is genuinely present) or find Grade 2H’s heavy-hex, higher-hardness route sufficient. Grade 4 remains a legitimate, standard-recognized option for the specific gap between those two paths.
Akbar Fasteners Pvt. Ltd. exports to over 50 countries, and our Grade 4 nut range is manufactured and verified by mechanical testing under our ISO 9001:2015 quality system.
Where This Grade Genuinely Applies
Genuine Strength Increase Over Grade 2
Medium carbon content plus quench-and-temper delivers a real proof load improvement.
No Alloy Content Required
Strength achieved through carbon and heat treatment alone — no chromium-molybdenum needed.
Cost-Efficient for Ambient Service
Appropriate where elevated-temperature creep resistance isn’t a genuine service requirement.
Verified Mechanical Properties
Batch hardness and proof load testing confirms consistent heat-treated strength for every lot.
Choosing Between Related Carbon & Alloy Steel Grades
Grade 2 / 2M
The widely-used standard match for ASTM A193 Grade B7 — Grade 4 sits above this in mechanical capability.
View Grade 2 / 2M →Grade 4 (This Page)
Medium carbon steel, quenched and tempered above Grade 2’s range, without alloy content.
You Are HereGrade 2H
Heavy hex, higher-hardness carbon steel nut, another widely specified alternative high-strength option.
View Grade 2H →Grade 2 vs Grade 4 — Quick Reference
Confirming whether the joint genuinely needs strength beyond Grade 2’s range before specifying the higher grade. This table is the quick reference we use with buyers before quoting.
| Aspect | Grade 2 | Grade 4 |
|---|---|---|
| Base Material | Carbon or alloy steel | Medium carbon steel |
| Heat Treatment | Quenched and tempered | Quenched and tempered, higher target range |
| Relative Strength | Standard structural-grade | Higher than Grade 2 |
| Alloy Content | Present in alloy variants | Not required |
Grade 4 Specification Details
Nominal Composition
- Carbon Medium Range
- Manganese Controlled Range
- Alloying Elements Not Required
- Heat Treatment Required — Quench & Temper
Typical Mechanical Range
- Proof Load Higher Than Grade 2
- Condition Quenched and Tempered
- Hardness Elevated Range
- Service Temperature Ambient to Moderate
Fastener Types We Manufacture
- Hex Nuts Standard & Heavy Hex
- Jam Nuts Thin Profile
- Coating Options Zinc, Black Oxide, Plain
- Custom Sizes On Request
Application Areas
Wherever ambient-to-moderate temperature service genuinely needs strength beyond Grade 2, without requiring alloy steel.
Higher-Load Structural Steelwork
more than Grade 2 provides
Heavy Machinery Assembly
bolting at ambient temperature
General Industrial High-Load Bolting
strength, ambient service
Non-Critical Pressure Equipment
isn’t specifically required
Standard Export Documentation
Prepared as standard practice for every Grade 4 nut shipment.
Mill Test Certificate (MTC)
Heat number, chemical composition, and mechanical property verification for every lot.
Mechanical Property Report
Confirms actual quenched and tempered hardness meets the specified Grade 4 proof load requirement.
Certificate of Conformance
Confirms the shipment matches the purchase order grade/size specification in full.
Certificate of Origin (COO)
Confirms India as country of manufacture for destination customs purposes.
Dimensional Inspection Report
Confirms thread pitch, across-flats dimension, and thickness conform to ASME B18.2.2.
Commercial Invoice & Packing List
Itemized value, Incoterm, and detailed carton/weight breakdown for customs clearance.
Internationally Recognised Standards Coverage
Related Fastener Grades & Materials
ASTM A194 Grade 2 / 2M
Our widely-used standard grade matching ASTM A193 Grade B7, which Grade 4 exceeds in strength.
View Grade 2 / 2M →ASTM A194 Grade 2H
Our heavy hex, high-hardness carbon steel grade — another widely specified alternative high-strength option.
View Grade 2H →ASTM A194 Grade 1
Our general-purpose carbon steel baseline, for applications not requiring elevated strength.
View Grade 1 →Stainless Steel Fasteners Manufacturer India
Our broader fastener manufacturing capability across all major carbon, alloy, and stainless grades.
View SS Manufacturer Guide →Need Higher Strength
Without Alloy Content?
Tell us your service temperature and strength requirements — we’ll confirm whether Grade 4 fits, and quote with full documentation. Akbar Fasteners Pvt. Ltd. responds within 24 hours.
Sales: +91 724 0000 733 · Support: +91 800 9315 333 · sales@akbarfasteners.in