Our A2-70 grade SS 321 hexagonal bolts handle high-temperature environments where standard fasteners fail.
In oxidizing environments, you get aerospace-grade performance without the price of 316 stainless steel.
Each hexagonal bolt undergoes our heat-resistant treatments:
Cold-forged from German 321 stainless steel wire
Solution annealed at 1900°F (1038°C) to dissolve carbides
Threads rolled to UNRC 2A tolerances
Electropolished to ASTM B912
We perform eddy current testing, which can reveal micro-cracks in high-temperature bolts that standard milling cutters cannot.
We operate a dedicated production line with the following features:
Monthly production capacity of 8 million pieces (capable of accommodating peak factory downtime)
Laser-etched marking (permanent grade identification)
MTC uses blockchain to track the entire process from melting to shipment
Our warehouse stocks 3M+ SS 321 hexagonal bolts in sizes M8-M24, all complying with ASME B18.2.1 standards, and provides real-time inventory updates.
Wholesale Partners
Volume Benefits: Orders over 75,000 units receive a 10% discount and a free RoHS/REACH kit.
On-Time Guarantee: Shipping within 14 days (Delays? We cover 40% of air freight costs).
Compliance Ready: CE/PED/NACE MR0175 documentation provided free of charge.
Chemical Composition
Cr: 17-19%, Ni: 9-12%, Ti: 5×C–0.70% (minimum 0.4% Ti), C: ≤0.08%, Mn: ≤2%, Si: ≤1%, N: ≤0.1%
Mechanical Strength
Tensile strength: ≥515 MPa
Yield strength: ≥205 MPa
Hardness: ≤217 HB (Brinell) / ≤95 HRB (Rockwell)
Elongation: ≥40% (in 50mm)
Corrosion Resistance
Superior to 304 in high-temperature and oxidizing environments.
Titanium eliminates intergranular corrosion (a critical issue in 304 after welding or high-heat exposure).
Resists pitting in moderate chloride environments (though less than 316/316Ti).
Performs well in nitric acid and oxidizing media.
Temperature Range
Continuous service: -270°C to 870°C
Excellent for both cryogenic conditions and high-heat applications (e.g., exhaust systems, furnaces).
Magnetic Behavior
Non-magnetic in annealed condition (suitable for sensitive electronic or medical environments).
Metric Size (M)
Thread Pitch (mm)
Hex Head Width (mm)
Hex Head Height (mm)
Length Range (mm)
Imperial Equivalent
Thread Type (Imperial)
1/8" (approx.)
UNC (1/8"-40), UNF (1/8"-48)
UNC (5/16"-18), UNF (5/16"-24)
UNC (3/8"-16), UNF (3/8"-24)
UNC (1/2"-13), UNF (1/2"-20)
UNC (5/8"-11), UNF (5/8"-18)
Defines metric hex bolt dimensions, thread tolerances, and head geometry.
ASME B18.2.1
Governs imperial hex bolt specifications for industrial and structural use.
Specifies full-threaded metric hex bolts with strict dimensional tolerances.
Covers alloy steel and stainless steel bolts for high-temperature service (includes 321).
High-Temp Performance
Excellent (up to 870°C; resists scaling).
Moderate (up to 870°C but prone to corrosion).
Good (up to 815°C).
Superior (up to 870°C; better than 316).
Weldability
Excellent (no post-weld annealing needed).
Good but prone to intergranular corrosion.
Good but may need annealing post-weld.
Excellent (no post-weld annealing).
Intergranular Corrosion
Resistant (titanium stabilizes carbides).
Vulnerable after welding/high heat.
Vulnerable after welding/high heat.
Resistant (titanium-stabilized).
Chloride Resistance
Moderate (suitable for low chloride levels).
Poor (prone to pitting in seawater).
Excellent (resists seawater/chlorides).
Excellent (same as 316, better at high temps).
Higher than 304, lower than 316/316Ti.
Moderate to high.
Highest (due to molybdenum + titanium).
Frequently Asked Questions
Q: Do you have experience exporting to our country/region?
A: We have exported to over 50 countries, including the US, EU, Southeast Asia, and the Middle East. We're familiar with local import regulations.
Q: What testing reports can you provide for the products?
A: We can provide reports such as pressure test, chemical composition analysis, and mechanical property test, as per your request.
Q: How do you pack the products to avoid damage during shipping?
A: We use seaworthy packaging: small products in cartons or wooden crates, and large ones in steel frames or pallets with waterproof film.
