ASTM A193
Grade B6 Stud Bolts
Mumbai · India
What Is ASTM A193 Grade B6 Stud Bolts
Grade B6 is a martensitic stainless steel — Type 410, containing roughly 11.5 to 13.5% chromium — hardened and tempered to develop strength that standard austenitic grades like B8 simply cannot reach without cold working. Unlike austenitic stainless (304, 316), which gets its corrosion resistance and toughness from a face-centered crystal structure that can’t be hardened by heat treatment, martensitic stainless can be quenched and tempered much like carbon or alloy steel, developing higher hardness and tensile strength as a result.
That strength comes at the cost of corrosion resistance relative to austenitic grades. Type 410’s lower chromium content and martensitic structure give it noticeably less corrosion resistance than 304 or 316 — good enough for many mild atmospheric and moisture exposures, but not intended for aggressive chloride or acidic environments. Grade B6 occupies a specific niche as a result: applications like valve stems and turbine components, where cyclic mechanical loading and moderate corrosion exposure both matter, and where full nickel alloy performance isn’t required or economically justified.
Akbar Fasteners Pvt. Ltd. exports to over 50 countries, and our A193 Grade B6 stud bolt range is manufactured with the same ISO 9001:2015 quality system and full mill test documentation as our B7, B8, and nickel alloy stud bolt lines.
Where B6 Genuinely Fits the Job
Higher Strength Than Austenitic Grades
Quench-and-temper hardening gives meaningfully higher tensile and yield strength than standard 304/316-based B8 without a full alloy steel upgrade.
Moderate Corrosion Resistance Included
Chromium content gives working corrosion resistance for mild atmospheric and moisture exposure without needing full austenitic performance.
Cost-Effective Versus Nickel Alloys
Delivers the strength-plus-corrosion-resistance combination valve and turbine applications need at a fraction of nickel alloy cost.
Honest Guidance on Suitability
We flag when B6’s more limited corrosion resistance isn’t sufficient for a given chloride or acid environment before quoting it.
Grade B6 vs B8 vs B7 vs B6X
Grade B6 sits deliberately between austenitic stainless and full alloy steel — more strength than B8, more corrosion resistance than B7, but a genuine compromise rather than the best of both. The comparison below is the one we walk through with buyers before quoting, so the trade-off is understood rather than assumed.
| Property | Grade B6 | Grade B8 (Cl.1) | Grade B7 | Grade B6X |
|---|---|---|---|---|
| Base Material | Type 410 (S41000) | Type 304 (S30400) | Cr-Mo alloy steel | Type 410, low-carbon variant |
| Structure | Martensitic | Austenitic | Martensitic (carbon-alloy) | Martensitic |
| Min Tensile Strength | 110 ksi (760 MPa) | 75 ksi (515 MPa) | 125 ksi (860 MPa) | 95 ksi (655 MPa) |
| Corrosion Resistance | Moderate | Good — better than B6 | Low — needs coating | Moderate, better toughness |
| Best Suited For | Valve stems, turbine components | General corrosion-resistant, low load | High-strength general flange bolting | Where B6 toughness needs improving |
| Relative Cost | Moderate | Moderate | Lower | Moderate |
ASTM A193 B6 Product Range
B6 Stud Bolts
Hardened and tempered Type 410 stud bolts for valve, turbine, and moderate-corrosion high-strength applications.
Grade 6 Hex Nuts
Matching heavy hex nuts manufactured to pair correctly with B6 stud bolts per ASTM A194.
B6X Stud Bolts
Improved-toughness variant of B6 for applications needing better impact resistance at moderate strength.
B8 Stud Bolts
Austenitic stainless alternative where corrosion resistance matters more than raw strength.
Grade B6 Technical Overview
Type 410 Alloying Elements
- Chromium 11.5 – 13.5%
- Carbon (max) 0.15%
- Manganese (max) 1.0%
- Nickel Not intentionally added
- Iron Balance
Property Ranges (per ASTM A193)
- Tensile Strength 110 ksi min (760 MPa)
- Yield Strength 85 ksi min (585 MPa)
- Elongation 15% min
- Hardness Max per diameter, per spec
- Testing MTC / NABL on request
Available Dimensions
- Diameter Range 1/4″ – 4″
- Metric Equivalent M6 – M100
- Stud Length Custom to drawing
- Thread Type UNC / UNF / 8UN
- Finish As-machined / Passivated
Application Areas
Wherever strength and moderate corrosion resistance both matter more than either alone.
Valve Stems & Components
and bonnet bolting
Turbine Components
steam and gas turbine parts
Power Generation Equipment
power plant components
Pump & Compressor Parts
equipment bolting
Petrochemical Machinery
equipment fastening
General Industrial Machinery
with moderate corrosion needs
Structural Machinery Parts
austenitic strength falls short
General Engineering
moderate-corrosion bolting
Standard Export Documentation
Prepared as standard practice for every Grade B6 shipment.
Mill Test Certificate (MTC)
Heat number, chemical composition, and mechanical property verification for every lot.
Certificate of Conformance
Confirms the shipment matches the purchase order specification and grade in full.
Certificate of Origin (COO)
Confirms India as country of manufacture for destination customs purposes.
Commercial Invoice & Packing List
Itemized value, Incoterm, and detailed carton/weight breakdown for customs clearance.
NABL Accredited Test Reports
Independent mechanical and chemical testing available on request for critical applications.
Bill of Lading
Ocean or air freight shipping document confirming carrier, mode, and consignee details.
Internationally Recognised Standards Coverage
Related Fastener Grades & Materials
ASTM A193 Grade B7 Stud Bolts
Higher-strength alloy steel where corrosion resistance isn’t required.
View Grade B7 →ASTM A193 Grade B8 Stud Bolts
Austenitic stainless option with better corrosion resistance than B6.
View Grade B8 →ASTM A193 Grade B7M Stud Bolts
Hardness-controlled Cr-Mo bolting for sour service oil & gas applications.
View Grade B7M →Fastener Applications By Industry
A guide to matching fastener material grades to the right industry and environment.
View Applications Guide →Need Strength
With Moderate Corrosion Resistance?
Tell us the load and the environment — and we’ll confirm whether B6 or an alternative grade is the right fit for your valve, turbine, or machinery application. Akbar Fasteners Pvt. Ltd. responds within 24 hours.
Sales: +91 724 0000 733 · Support: +91 800 9315 333 · sales@akbarfasteners.in