ASTM A194
Grade 8C
Stainless Steel Nuts
Why 8C Isn’t Interchangeable With 8M
It’s tempting to treat every lettered A194 stainless grade as answering the same basic question — “which corrosion problem does this solve?” — but 8C and 8M solve two genuinely different problems, and neither substitutes well for the other.
Grade 8M’s molybdenum addresses chloride-driven pitting and crevice corrosion — a localized attack mechanism most relevant in seawater, de-icing salts, and similar chloride-bearing environments. Grade 8C’s niobium addresses something else entirely — it preferentially combines with carbon to form stable niobium carbides instead of chromium carbides, protecting grain-boundary chromium from depletion during and after welding at sustained high temperature, the specific failure mode called sensitization or weld decay.
A buyer facing a genuinely high-temperature welded assembly gains nothing from 8M’s molybdenum — chloride resistance doesn’t help with sensitization. Equally, a buyer facing chloride exposure gains nothing from 8C’s niobium stabilization if the assembly isn’t being welded at high temperature in the first place. Confirming which failure mode is actually the concern is the entire decision.
Akbar Fasteners Pvt. Ltd. exports to over 50 countries, and our Grade 8C nut range is verified by chemical composition and mechanical testing under our ISO 9001:2015 quality system.
Where This Grade Genuinely Applies
Genuine Weld-Decay Resistance
Niobium carbide formation protects grain-boundary chromium, resisting sensitization at high temperature.
Correct Default Pairing With B8C Studs
Matched material and mechanical properties for straightforward assembly compatibility.
Correct Choice for High-Temperature Welded Assembly
Reliable where sustained heat and welding, not chloride exposure, are the genuine service concern.
Verified Chemical & Mechanical Properties
Batch testing confirms genuine niobium content and mechanical properties for every lot.
Grade 8 vs 8M vs 8C — Three Genuinely Different Answers
Grade 8
No special corrosion strategy. Genuinely sufficient where neither chloride exposure nor weld-decay at high temperature is a concern.
View Grade 8 → 316 Base — Chloride ResistanceGrade 8M
Molybdenum addresses chloride-driven pitting and crevice corrosion, the failure mode 8C’s niobium doesn’t help with.
View Grade 8M →Grade 8C (This Page)
Niobium addresses sensitization at high welding temperature, the failure mode 8M’s molybdenum doesn’t help with.
You Are HereGrade 8M vs Grade 8C — Quick Reference
Confirming which failure mode is genuinely the concern — chloride pitting or high-temperature sensitization — decides between these two grades. This table is the quick reference we use with buyers before quoting.
| Aspect | Grade 8M (316) | Grade 8C (347) |
|---|---|---|
| Key Addition | Molybdenum | Niobium |
| Protects Against | Chloride pitting / crevice corrosion | High-temperature weld sensitization |
| Best Suited For | Marine, chloride-bearing exposure | High-temperature welded assemblies |
| Chloride Resistance vs Weld Resistance | Improved chloride, standard weld | Standard chloride, improved weld |
Grade 8C Specification Details
Nominal Composition
- Chromium 17.0 – 19.0%
- Nickel 9.0 – 13.0%
- Niobium (Columbium) ~10x Carbon Min
- Carbon ≤0.08%
Typical Mechanical Range
- Proof Load Per ASTM A194 Grade 8C
- Condition Solution Annealed
- Hardness Standard Annealed Range
- Weld-Decay Resistance Stabilized
Fastener Types We Manufacture
- Hex Nuts Standard & Heavy Hex
- Jam Nuts Thin Profile
- Matching Studs ASTM A193 Grade B8C
- Custom Sizes On Request
Application Areas
Wherever genuine high-temperature welded service, not chloride exposure, is the deciding factor.
High-Temperature Welded Piping
sustained heat and weld exposure
Furnace & Heat Treatment Equipment
sustained elevated temperature
Power Generation Steam Systems
steam and process lines
Refinery Process Furnace Piping
weld exposure bolting
Chemical Process High-Temp Vessels
assemblies at sustained heat
Petrochemical Reactor Vessels
welded reactor bolting
Nuclear-Adjacent Process Equipment
critical traceable bolting
General High-Temperature Welded Bolting
needing weld-decay resistance at heat
Standard Export Documentation
Prepared as standard practice for every Grade 8C nut shipment.
Mill Test Certificate (MTC)
Heat number, chemical composition, and mechanical property verification for every lot.
Chemical Composition Report
Confirms actual niobium content falls within the specified 347 grade range.
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.
NABL Accredited Test Reports
Independent mechanical, dimensional, and corrosion testing available on request.
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 8M
Our molybdenum-bearing 316-based grade, for chloride and marine service rather than weld decay.
View Grade 8M →ASTM A194 Grade 8
Our 304-based baseline stainless nut grade, without either special corrosion strategy.
View Grade 8 →ASTM A193 Grade B8CLN / B8CLNA
Our low-carbon, nitrogen-enhanced niobium-stabilized bolting family, based on 347LN.
View B8CLN / B8CLNA →Stainless Steel Fasteners Manufacturer India
Our broader stainless steel fastener manufacturing capability across all major grades.
View SS Manufacturer Guide →High-Temperature Welding,
Not Chloride Exposure?
Tell us your service temperature and welding requirements — we’ll confirm whether Grade 8C genuinely fits or whether 8M’s chloride resistance is what you actually need, 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