A325 Bolt Strength – Complete Technical Guide for B2B Buyers (2026)
Meta Title: A325 Bolt Strength Chart | ASTM F3125 Grade A325 Specifications | TJJ Fasteners
Search Intent Response: A325 bolts, now designated under ASTM F3125 Grade A325, are high-strength structural bolts with a minimum tensile strength of 120,000 psi for diameters 1″ and below, and 105,000 psi for diameters over 1″. They are made from medium-carbon steel, quenched and tempered, and are the standard for steel-to-steel structural connections in North American construction. This guide provides the complete strength data, compliance requirements, and procurement considerations for import managers and brand owners sourcing from China.
Senior Metallurgical Engineer & Supply Chain Specialist – 20 years in structural fasteners
Why A325 Bolt Strength Matters for Your Next Procurement
As an import manager or brand owner sourcing fasteners for critical infrastructure, you need verifiable, consistent mechanical properties. A325 bolts are the backbone of high-rise buildings, bridges, and heavy equipment. Understanding their strength grades, testing standards, and supply chain nuances will help you avoid costly rejections at job sites. This article covers everything from raw material chemistry to torque charts, OEM customization, and lead times from experienced Chinese foundries like SHIJIAZHUANG TJJ TRADE CO.,LTD.
Common Procurement Pain Points & How We Solve Them
| Pain Point | Impact on Your Business | TJJ Solution |
|---|---|---|
| Inconsistent hardness/strength batch to batch | Reduces structural safety; increases liability | Full in-house heat treatment monitoring & SPC; ISO 9001:2015 certified |
| Long lead times from overseas suppliers | Project delays and penalty costs | 30-45 days standard; express options available |
| Mislabeling/spec non-compliance | Rejected by QC inspectors on site | ASTM F3125 mill certificates; third-party inspection (SGS, TÜV) upon request |
| Difficulty sourcing custom lengths / coatings | Limits design flexibility | OEM/ODM services; hot-dip galvanized, HDG, Dacromet available |
A325 Bolt Strength: Technical Parameters & Comparisons
Mechanical Properties Table (ASTM F3125 Grade A325)
All data is for reference. Confirm exact values with your Mill Test Certificate.
| Bolt Diameter (in) | Tensile Strength, min (ksi) | Yield Strength, min (ksi) | Hardness (Rockwell C) | Core Hardness (HBW) |
|---|---|---|---|---|
| 1/2″ – 1″ | 120 | 92 | 24–35 | 235–321 |
| 1⅛″ – 1½″ | 105 | 81 | 19–30 | 207–285 |
| Over 1½″ (Type 1) | 105 | 81 | 19–30 | 207–285 |
a325 bolt strength structural bolts a325 / a325 bolt tensile strength grade 8 bolts strength
Material Chemistry (A325 Type 1 – Medium Carbon Alloy)
- Carbon: 0.30–0.52%
- Manganese: 0.60% min
- Phosphorus: 0.035% max
- Sulfur: 0.040% max
- Boron: 0.0005–0.003% (if added)
Our foundry in Shijiazhuang, Hebei Province, uses electric arc furnace (EAF) melted steel with tight chemistry control to ensure consistent hardenability.
Comparison: A325 vs. A490 vs. Grade 8.8
| Grade | Tensile (ksi) | Common Use | Coating Options |
|---|---|---|---|
| A325 (1″ & below) | 120 | Steel-to-steel structural connections | Plain, HDG, Dacromet |
| A490 (all sizes) | 150–170 | High-strength joints for bridges/towers | Only plain (no HDG) |
| Grade 8.8 (metric) | 116 | Similar to A325 but used globally | Plain, zinc, HDG |
Key Insight: A325 offers the best cost-strength balance for most structural applications. A490 is stronger but cannot be hot-dip galvanized due to hydrogen embrittlement risk.
Why Import Managers Trust TJJ for A325 Bolts
TJJ’s 20,000 m² facility in Shijiazhuang, Hebei
Advanced quench & temper line for A325 strength
In-house tensile & hardness testing lab
- Established 2004 – Over 20 years as one of China’s earliest dedicated casting & fastener foundries.
- 120+ skilled workers running 24/7 with strict SPC (Statistical Process Control).
- Quality certifications: ISO 9001:2015, ASTM F3125 compliant mill certs.
- Capacity: 3,000 metric tons per year; monthly output of A325 bolts exceeds 500 tons.
- MOQ: 5,000 pcs per size (stock sizes ½”–1½” in plain finish; HDG orders from 10,000 pcs).
- Lead Time: 30 days for stock sizes; 45 days for custom lengths/coatings.
- OEM/ODM: We can produce special head markings, custom lengths, and unique coatings (PTFE, black oxide, phosphated).
- Packaging: Bulk in pallets with plastic/steel strapping; small packs (100/500/1000 pcs) with labels; export-grade seaworthy cartons and wooden pallets (IPPC heat-treated).
Shipping & Commercial Terms
We offer FOB Tianjin / Qingdao, CIF to major US ports (Los Angeles, Long Beach, Houston, New York). Payment options: T/T (30% deposit, 70% balance against BL copy) or L/C at sight. For trial orders, we accept PayPal for up to $4,000.
What Our Customers Say
VP of Operations, Orion Structural Steel, USA
“We switched to TJJ after inconsistent hardness from another supplier. Their A325 bolts passed all our torque-tension tests. Lead time was 28 days – 5 days faster than promised. Strongly recommend for critical fasteners.”
Sourcing Manager, Pacific Bridge Supply LLC
“OEM custom length A325 bolts with HDG – TJJ made it easy. The mill certs are clear and traceable. We’ve ordered three shipments and every one arrived defect-free. Their communication is top-notch.”
Owner, Eagle Constructors, Canada
“As a small contractor, I appreciate that TJJ accepts MOQ of 5,000 pcs. Their pricing is competitive, and the product quality is consistent with US-made bolts. Will continue buying.”
Project Engineer, Pinnacle Engineering Group, Mexico
“TJJ provided third-party inspection (SGS) at no extra cost for our first order. The bolts performed perfectly in pre-construction torque tests. They understand ASTM standards thoroughly.”
Get Your Custom A325 Bolt Quotation Today
Stop risking project delays with unreliable fastener supply. SHIJIAZHUANG TJJ TRADE CO.,LTD. brings two decades of foundry expertise to every A325 bolt we ship. Whether you need standard sizes, special coatings, or unique head markings, our team is ready to deliver.
Contact Us Now for Fast & Reliable Supply
📞 Tel/WhatsApp: +86-15511680668
📧 Email: sindyhao2014@163.com
🌐 Website: www.tjjironcastings.com
Add: Shijiazhuang, Hebei Province, China | FOB/CIF terms available
John Calderon – Senior Metallurgical Engineer & Supply Chain Specialist. John has spent 20 years in fastener design and procurement across North America and Asia. He advises large contractors and importers on material compliance and cost-efficient sourcing. This article is based on his field experience and collaboration with TJJ’s technical team.
Disclaimer: All data, figures, and specifications provided in this article are for general informational and marketing purposes. They do not constitute a guarantee or warranty. Actual product performance may vary. Always refer to the Mill Test Certificate and order confirmation for final specifications. SHIJIAZHUANG TJJ TRADE CO.,LTD. reserves the right to update product parameters without prior notice.
