ASTM A193
Grade B8LN Stud Bolts
Mumbai · India
Why ASTM A193 Grade B8LN Stud Bolts Exists
The “L” in B8LN refers to low carbon — the same low-carbon principle behind 316L stainless generally. Reducing carbon content to 0.030% maximum prevents chromium carbide precipitation at grain boundaries during welding, which is what causes sensitization and subsequent intergranular corrosion in weld heat-affected zones. That’s a genuine benefit for stud bolts used near welded piping joints — but lowering carbon also lowers the alloy’s strength, since carbon itself contributes to strength in austenitic stainless steel.
Nitrogen addition is the fix — the “N” in B8LN. Nitrogen is a strong austenite stabilizer and solid-solution strengthener that doesn’t carry carbon’s sensitization risk, so adding a controlled amount (typically 0.10–0.16%) recovers much of the strength lost by reducing carbon, without reintroducing the original weldability problem. The result is a grade that behaves almost like a strength-recovered 316L — genuinely useful wherever low-temperature toughness, corrosion resistance near welds, and reasonable strength all matter simultaneously, which is exactly the combination cryogenic and low-temperature piping systems demand.
Akbar Fasteners Pvt. Ltd. exports to over 50 countries, and our ASTM A193 Grade B8LN stud bolt range is manufactured with controlled carbon and nitrogen content, verified by mechanical and chemical testing under our ISO 9001:2015 quality system.
Where B8LN Genuinely Earns Its Place
Weld-Zone Sensitization Resistance
Low carbon content protects heat-affected zones near welds from chromium carbide precipitation and intergranular attack.
Strength Recovered via Nitrogen
Nitrogen addition offsets the strength loss typically associated with low-carbon 316L, without reintroducing sensitization risk.
Good Low-Temperature Toughness
Retains useful impact toughness at cryogenic temperatures, where many carbon and alloy steel grades become brittle.
Standard 316-Family Corrosion Resistance
Molybdenum content carries through the same chloride and pitting resistance associated with the 316 family generally.
Grade B8LN Detailed Properties
UNS S31653 Alloying Elements
- Chromium 16.0 – 18.0%
- Nickel 10.0 – 14.0%
- Molybdenum 2.0 – 3.0%
- Nitrogen 0.10 – 0.16%
- Carbon (max) 0.030%
Per ASTM A193 (Class 1, Annealed)
- Tensile Strength 550 MPa min
- Yield Strength 240 MPa min
- Elongation 35% min
- Hardness ~ 96 HRB max
- Testing MTC / NABL on request
Available Dimensions
- Metric Diameter M6 – M64
- Imperial Diameter 1/4″ – 4″
- Length Custom to drawing
- Thread Type UNC / UNF / Metric
- Matching Nut ASTM A194 Grade 8LN
Grade B8LN vs B8M vs B8MLN
B8LN sits alongside two closely related grades that solve overlapping but distinct problems. The comparison below is the one we walk through with buyers before quoting, so the grade matches whether molybdenum content, low temperature toughness, or both actually matter for the application.
| Property | Grade B8LN | Grade B8M | Grade B8MLN |
|---|---|---|---|
| Base Type | 316L + Nitrogen | 316 (Standard Carbon) | 316L + Nitrogen |
| Molybdenum Content | 2.0 – 3.0% | 2.0 – 3.0% | 2.0 – 3.0% |
| Carbon Content | 0.030% max | 0.08% max | 0.030% max |
| Sensitization Resistance | Good | Standard | Good |
| Best Suited For | Low-temp service, weld-adjacent bolting | General 316-grade bolting needs | Combines B8LN benefit with same Mo range |
Application Areas
Wherever low-temperature toughness and weld-zone corrosion resistance both matter.
LNG & Cryogenic Piping
and pipe joint bolting
Chemical Processing
requiring sensitization resistance
Refrigeration Systems
refrigeration piping bolting
Air Separation Plants
equipment fastening
Petrochemical Welded Assemblies
in process piping systems
Marine LNG Carriers
system fastening
Pharmaceutical Processing
hygienic welded assemblies
General Low-Temperature Bolting
cryogenic and cold service
Standard Export Documentation
Prepared as standard practice for every Grade B8LN stud bolt 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, chemical, and low-temperature impact testing available on request.
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 B8 Stud Bolts
The Type 304 base grade this specification family builds from.
View Grade B8 →Stainless Steel 316 Fasteners
The base 316 family that B8LN’s molybdenum content and corrosion resistance builds from.
View SS 316 →ASTM A276 Type 321 Fasteners
Another sensitization-resistant stainless grade, stabilized with titanium instead of low carbon.
View Type 321 →Stainless Steel Fasteners Manufacturer in India
Our full stainless steel grade range and manufacturing process explained.
View Stainless Range →Need Low-Temp Toughness
Near a Welded Joint?
Tell us your service temperature and weld proximity — we’ll confirm whether Grade B8LN is the right fit for your application. Akbar Fasteners Pvt. Ltd. responds within 24 hours.
Sales: +91 724 0000 733 · Support: +91 800 9315 333 · sales@akbarfasteners.in