Our ASTM A307 Grade A Mild Steel Hex Bolts deliver reliable strength for everyday construction and machinery. Cold-forged from low-carbon steel (max 0.29% carbon per ASTM A307), they hit 60,000 PSI tensile strength - 15% higher than generic hardware store bolts. Third-party tests show they handle 120 ft-lbs torque without head rounding (per ASME B18.2.1), making them ideal for structural steel connections or agricultural equipment. The secret? Our controlled sulfur content (<0.05%) prevents brittle fractures in freezing temps down to -20°F (-29°C). Compared to stainless alternatives, you'll save 50-70% per thousand pieces while getting certified reliability for non-corrosive applications.
Every Mild Steel Hex Bolt gets battle-ready treatment:
Cold-forged using Japanese dies (denser grain structure vs. hot forging)
Rolled threads to ASME B1.1 Class 2A fit (25% stronger than cut threads)
Zinc-plated per ASTM B633 Type II (96hr salt spray tested)
100% torque-tested (we weed out 3% with hidden forging flaws)
We radius the head-to-shank transition - stops stress cracks in vibrating conveyors.
Running 18 automated lines with:
30 million-piece monthly output (handles warehouse construction booms)
Real-time PMI checks (XRF guns verify chemistry on every 100th piece)
Laser-etched grade markings (no fading like ink stamps)
Barcode-tracked batches from coil to crate
Urgent order? Our Rotterdam hub stocks 20M+ Grade A hex bolts (1/4"-1" sizes) - all CE marked and ready for 48hr EU delivery.
For wholesale partners
Volume power: Orders >250,000pcs get 12% discount + free RoHS kits
On-time pledge: 99% ship in 10 days (delayed? We cover air freight)
No-snap guarantee: Shear below 45,000 PSI? Free replacement + $500 compensation
Compliance pack: Free REACH/UKCA docs + test samples
High carbon steel (carbon content: 0.60%–1.05%, often alloyed with manganese for enhanced strength; e.g., SAE 1060, 1080, or ASTM A325 Type 3 in some high-strength variants)
Mechanical Properties
Tensile Strength: 800–1200 MPa (116–174 ksi, varies by heat treatment)
Yield Strength: 600–900 MPa (87–130 ksi)
Hardness: 20–35 HRC (after quenching and tempering)
Elongation: 5%–15% (lower ductility than low/mild carbon steel)
Hex Head Feature
6-sided hexagonal head (standardized across sizes for wrench compatibility); head height proportional to bolt diameter (e.g., 1.5× diameter for metric, 2× diameter for imperial in some standards)
Thread Standards
Metric: ISO 898-1 (coarse/fine threads: M5–M64)
Imperial: UNC/UNF (Unified National Coarse/Fine) per ASME B1.1 (1/4"–2")
Diameter: M5–M64 (metric); 1/4"–2" (imperial)
Length: 10 mm–1000 mm (metric); 1"–40" (imperial) (custom lengths available)
Heat Treatment
Quenched and tempered (Q&T): heated to 800–900°C, rapidly cooled (quenched) in water/oil, then tempered at 300–600°C to balance strength and brittleness
Surface Finish
Plain (black oxide for minor corrosion resistance)
Zinc-plated (electroplated or hot-dip for moderate corrosion protection)
Galvanized (for outdoor/moist environments)
Phosphated (for paint adhesion)
Standards Compliance
ISO 898-1 (metric high-strength bolts)
ASTM A325 (structural high-strength bolts, some grades use high carbon steel)
SAE J429 (automotive high-strength fasteners)
Key Applications
Heavy machinery: engine mounts, gearbox connections
Construction: structural steel joints, bridge components (high-load areas)
Automotive: suspension systems, axle bolts
Industrial: press tools, Mold fixation (die clamping)
Key Characteristics
High strength: Ideal for high-tensile, heavy-load applications
Low ductility: Prone to brittleness; not suitable for shock/vibration (risk of fracture)
Corrosion resistance: Poor (requires coatings in moist environments)
Frequently Asked Questions
Q: Can you print our company logo on the products?
A: Yes, we can print your logo via laser engraving or stamping, as long as you provide the design file.
Q: What is the minimum order quantity (MOQ) for custom products?
A: The MOQ for custom products depends on specifications, but generally starts from 1 pieces. For special cases, we can discuss further.
Q: How do you ensure the accuracy of product specifications?
A: Each product is inspected by our QC team using precision instruments, and we provide MTC (Material Test Certificate) to confirm specifications.
