Huaxia Steel — Professional Cold Work Tool Steel Supplier
15+ years of experience | ISO 9001 & SGS Certified | Factory-direct pricing | Custom sizes available | Worldwide shipping
What is O1 TOOL STEEL?
AISI O1 tool steel is a low-alloy cold work tool steel that must be hardened by oil quenching. It is by far the most widely used general-purpose tool steel due to its exceptional dimensional stability during heat treatment, minimal distortion, and highly reliable hardening response. The carefully balanced composition of manganese, chromium, and tungsten gives O1 an optimal combination of high hardness (63-65 HRC after quenching), good wear resistance, and sufficient toughness for most standard tool and die applications.
As a leading O1 tool steel supplier based in China, Huaxia Steel provides AISI O1 in various forms—plates, round bars, flat bars, and custom-cut pieces—all manufactured to ASTM A681 standards with full mill test certificates (MTC). Whether you need O1 for precision gauges, blanking dies, or cutting tools, we deliver consistent quality at competitive factory-direct pricing.
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Chemical Composition (wt%)
| Element | Min (%) | Max (%) |
|---|---|---|
| Carbon (C) | 0.85 | 1.00 |
| Silicon (Si) | 0.10 | 0.50 |
| Manganese (Mn) | 1.00 | 1.40 |
| Phosphorus (P) | — | 0.030 |
| Sulfur (S) | — | 0.030 |
| Chromium (Cr) | 0.40 | 0.70 |
| Tungsten (W) | 0.40 | 0.60 |
| Vanadium (V) | — | 0.30 |
Data per ASTM A681 / equivalent standards (2025/2026 Reference).
Mechanical & Physical Properties
- Hardness (Annealed): 183-212 HB
- Hardness (Oil Quenched, 800°C): 63-65 HRC
- Hardness (Tempered, 175-260°C): 57-63 HRC
- Tensile Strength (800°C OQ + 425°C Temper): 1,690 MPa (245 ksi)
- Yield Strength (800°C OQ + 425°C Temper): 1,500 MPa (218 ksi)
- Density: 7.85 g/cm³ (0.283 lb/in³)
- Elastic Modulus (20°C): 193 GPa (28 × 10⁶ psi)
- Thermal Conductivity (20°C): 32.0 W/m·K
Heat Treatment Guide
| Process | Temperature | Details |
|---|---|---|
| Annealing | 760-790°C (1400-1450°F) | Furnace cool at ≤22°C/hr to ~600°C; hardness 183-212 HB |
| Preheating | 650°C (1200°F) | Slow, uniform heating to avoid thermal stress |
| Austenitizing (Hardening) | 790-815°C (1450-1500°F) | Soak 10-30 minutes; oil quench |
| Quenching Medium | Oil | Quench to ~50-60°C; hardness reaches 63-65 HRC |
| Tempering | 175-260°C (350-500°F) | Hold 2 hours; final hardness 57-63 HRC |
Need Custom Heat Treatment Advice?
Our engineers can recommend optimal heat treatment parameters for your specific application.
Common Applications
- Cutting tools & knives
- Blanking & piercing dies
- Drawing & forming dies
- Coining & embossing tools
- Precision gauges & measuring instruments
- Bushings, mandrels & arbors
- Shear blades for light-gauge metal
- Woodworking cutters & planer blades
- Cold-forming punches
- Thread rolling dies
International Equivalent Grades
| Standard / Country | Grade Designation | Details |
|---|---|---|
| USA (AISI/SAE) | O1 | UNS T31501, ASTM A681 |
| Germany (DIN) | 1.2510 | 100MnCrW4 (superseded); 95MnWCr5 (1.2825) |
| EU (EN ISO) | 95MnWCr5 | EN ISO 4957 |
| Japan (JIS) | SKS3 | JIS G4401 / G4404 |
| China (GB) | 9CrWMn | GB/T 1299 |
| UK (BS) | BO1 | BS 4659 |
Available Forms & Dimensions
Round bars (dia 6-300mm), Flat bars (thickness 2-100mm), Steel plates (thickness 2-200mm, width up to 1500mm), Custom-cut blanks available
Custom sizes: Available upon request. Contact us with your specifications for a tailored quotation.
Why Choose Huaxia Steel as Your O1 TOOL STEEL Supplier?
Factory-Direct Pricing
Eliminate middlemen. Our direct mill partnerships ensure competitive pricing on every order, from small prototype quantities to container loads.
Certified Quality
Every shipment includes full mill test certificates (MTC/EN 10204 3.1). ISO 9001 certified. Third-party SGS inspection available on request.
Custom Processing
Cut-to-size, precision sawing, surface grinding, and heat treatment services. We deliver material ready for your production line.
Fast Global Logistics
Efficient shipping to North America, Europe, Middle East, Southeast Asia, and beyond. Standard lead time 7-15 days for stock items.
Frequently Asked Questions
Q: What is the maximum hardness achievable with O1 tool steel?
The maximum hardness depends on the specific grade. After proper heat treatment, typical maximum hardness ranges from 58-67 HRC. Refer to the heat treatment table above for specific tempering curves.
Q: Can O1 tool steel be welded?
Most tool steels can be welded for repair purposes, but it requires proper preheating, low-hydrogen electrodes, and post-weld heat treatment. For high-chromium grades like D2, welding is generally not recommended for structural applications. Always consult the manufacturer’s welding guidelines.
Q: What is the difference between O1 and other tool steel grades?
Each tool steel grade is optimized for specific applications. The key differentiators are wear resistance, toughness, hot hardness, and heat treatment method (air/oil/water). Compare grades based on your specific requirements: wear resistance (D2 > A2 > O1), toughness (S7 > H13 > A2), and hot hardness (M2 > H13 > D2).
Q: How do I order O1 tool steel from Huaxia Steel?
Simply contact us via the form on this page, email, or phone. Provide the grade, dimensions (thickness x width x length or diameter x length), quantity, and any special requirements such as surface finish or heat treatment condition. Our team will respond with a tailored quotation within 12 hours.
Q: What certifications do your tool steel products carry?
All Huaxia Steel tool steel products are supplied with full Mill Test Certificates (MTC/EN 10204 3.1) showing chemical composition and mechanical properties. We are ISO 9001:2015 certified, and third-party inspection (SGS, BV, TUV) is available upon request at no extra charge for orders above 5 tons.
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