Overview
A2 Tool Steel is a medium-alloy, air-hardening cold-work tool steel known for its excellent balance of toughness, wear resistance, dimensional stability, machinability, and heat treatment performance. Classified under the AISI A-series tool steels, A2 is widely used in tooling applications where both wear resistance and impact toughness are required.
Compared with D2 tool steel, A2 offers better toughness but lower wear resistance. Compared with O1 tool steel, A2 provides superior dimensional stability and lower distortion during heat treatment.
A2 is widely used in:
- Blanking Dies
- Punches
- Forming Dies
- Plastic Mold Components
- Shear Blades
- Machine Knives
- Gauges & Fixtures
- Precision Tooling
Because of its balanced performance and reliable heat treatment characteristics, A2 is one of the most widely used cold-work tool steels in manufacturing industries worldwide.
Material Specification
| Property | Value |
|---|---|
| Material Designation | A2 Tool Steel |
| Standard | ASTM A681 |
| UNS Number | T30102 |
| Material Family | Air-Hardening Cold Work Tool Steel |
| Density | 7.85 g/cm³ |
| Magnetic Property | Magnetic |
| Typical Supply Condition | Annealed |
| Standard Forms | Round Bar, Flat Bar, Plate, Block, Tooling Stock |
Chemical Composition
| Element | Content (%) |
|---|---|
| Iron (Fe) | Balance |
| Carbon (C) | 0.95–1.05 |
| Chromium (Cr) | 4.75–5.50 |
| Molybdenum (Mo) | 0.90–1.40 |
| Vanadium (V) | 0.15–0.50 |
| Manganese (Mn) | 0.50–1.00 |
| Silicon (Si) | 0.10–0.50 |
| Phosphorus (P) | ≤0.030 |
| Sulfur (S) | ≤0.030 |
The chromium and molybdenum content provide good wear resistance and deep hardening capability, while vanadium improves grain refinement and toughness.
Mechanical Properties
Annealed Condition
| Property | Value |
|---|---|
| Tensile Strength | 750–950 MPa |
| Yield Strength | 500–700 MPa |
| Hardness | 200–240 HB |
| Elastic Modulus | 210 GPa |
Hardened & Tempered Condition
| Property | Value |
|---|---|
| Hardness | 57–62 HRC |
| Toughness | Excellent |
| Wear Resistance | Excellent |
| Dimensional Stability | Outstanding |
Precision Tooling Condition
| Property | Value |
|---|---|
| Hardness | 58–60 HRC |
| Impact Resistance | Excellent |
| Service Life | Excellent |
Physical Properties
| Property | Value |
|---|---|
| Density | 7.85 g/cm³ |
| Melting Point | 1420–1460°C |
| Thermal Conductivity | 24 W/m·K |
| Electrical Resistivity | 0.65 μΩ·m |
| Thermal Expansion Coefficient | 10.8 × 10⁻⁶/K |
| Specific Heat Capacity | 460 J/kg·K |
Corrosion Resistance
| Environment | Performance |
|---|---|
| Indoor Environment | Good |
| Dry Atmosphere | Good |
| Humid Environment | Moderate |
| Outdoor Environment | Moderate |
| Marine Environment | Poor |
| Chemical Environment | Moderate |
A2 is not a stainless tool steel and should be protected in corrosive environments.
Recommended surface treatments:
- Black Oxide
- Nitriding
- TiN Coating
- TiCN Coating
- DLC Coating
- Hard Chrome Plating
- PVD Coating
Weldability
| Welding Process | Rating |
|---|---|
| TIG Welding | Fair |
| MIG Welding | Fair |
| Arc Welding | Fair |
| Laser Repair Welding | Good |
| Tool Steel Repair Welding | Good |
A2 offers better weldability than D2 and D3 due to its lower carbon content.
Recommended:
- Preheating Required
- Controlled Cooling Recommended
- Post-Weld Tempering Recommended
Machinability
| Process | Rating |
|---|---|
| CNC Turning | Good |
| CNC Milling | Good |
| Drilling | Good |
| Grinding | Excellent |
| EDM Machining | Excellent |
| Wire EDM | Excellent |
Machinability Comparison
| Material | Machinability |
|---|---|
| O1 Tool Steel | Excellent |
| A2 Tool Steel | Good |
| D2 Tool Steel | Fair |
| D3 Tool Steel | Fair |
| M2 Tool Steel | Fair |
A2 machines more easily than D2 while maintaining excellent tooling performance.
Heat Treatment
Annealing
| Parameter | Value |
|---|---|
| Temperature | 845–870°C |
| Cooling Method | Furnace Cool |
Preheating
| Parameter | Value |
|---|---|
| Temperature | 650–760°C |
Hardening
| Parameter | Value |
|---|---|
| Temperature | 955–980°C |
| Cooling Medium | Air Cooling |
Tempering
| Parameter | Value |
|---|---|
| Temperature | 175–540°C |
| Cycles | Double Temper Recommended |
Hardness After Heat Treatment
| Condition | Hardness |
|---|---|
| Annealed | 200–240 HB |
| Hardened | 60–63 HRC |
| Hardened & Tempered | 57–62 HRC |
Nitriding
| Property | Value |
|---|---|
| Surface Hardness | 65–72 HRC |
| Wear Resistance | Outstanding |
International Equivalent Grades
| Standard | Equivalent Grade |
|---|---|
| ASTM / AISI (USA) | A2 |
| UNS | T30102 |
| GB/T (China) | Cr5Mo1V |
| EN (Europe) | X100CrMoV5 |
| DIN (Germany) | 1.2363 |
| JIS (Japan) | SKD12 |
| ISO | X100CrMoV5 |
Available Forms
| Product Type | Availability |
|---|---|
| Round Bar | Yes |
| Flat Bar | Yes |
| Tool Steel Plate | Yes |
| Precision Ground Plate | Yes |
| Mold Blocks | Yes |
| Tooling Stock | Yes |
| Forgings | Yes |
Typical Applications
Tool & Die Industry
- Blanking Dies
- Piercing Dies
- Forming Dies
- Bending Dies
Precision Manufacturing
- Gauges
- Fixtures
- Precision Tooling
- Wear Components
Plastic Mold Industry
- Mold Inserts
- Core Components
- Ejector Systems
Cutting Applications
- Machine Knives
- Shear Blades
- Trimming Tools
Metal Processing
- Punches
- Cold Forming Tools
- Drawing Dies
General Engineering
- Wear Plates
- Guide Components
- Precision Mechanical Parts
Manufacturing Characteristics
| Manufacturing Process | Rating |
|---|---|
| CNC Machining | Excellent |
| Precision Grinding | Outstanding |
| EDM Machining | Excellent |
| Wire EDM | Excellent |
| Vacuum Heat Treatment | Outstanding |
| Nitriding | Outstanding |
| PVD Coating | Outstanding |
| Tool Grinding | Excellent |
Advantages
Excellent Toughness
Superior impact resistance compared with D2 and D3.
Outstanding Dimensional Stability
Minimal distortion during heat treatment.
Good Wear Resistance
Suitable for most cold-work tooling applications.
Excellent Machinability
Easier to machine than high-chromium tool steels.
Air-Hardening Capability
Reduces cracking and distortion risks.
Versatile Tool Steel
Suitable for a wide range of tooling applications.
Limitations
Lower Wear Resistance Than D2
Not ideal for extremely abrasive environments.
Not Stainless
Requires corrosion protection.
Lower Edge Retention Than D3
Less suitable for maximum-abrasion cutting applications.
Higher Cost Than O1
Due to alloy content and heat treatment performance.
Comparison with Other Tool Steels
| Property | A2 | D2 | D3 | O1 | SKD12 |
|---|---|---|---|---|---|
| Toughness | Excellent | Moderate | Lower | Good | Excellent |
| Wear Resistance | Excellent | Outstanding | Exceptional | Good | Excellent |
| Hardness | 62 HRC | 62 HRC | 64 HRC | 60 HRC | 62 HRC |
| Dimensional Stability | Outstanding | Excellent | Excellent | Good | Outstanding |
| Machinability | Good | Fair | Fair | Excellent | Good |
Comparison with Engineering Materials
| Material | Hardness Potential | Wear Resistance | Toughness |
|---|---|---|---|
| A2 Tool Steel | 62 HRC | Excellent | Excellent |
| D2 Tool Steel | 62 HRC | Outstanding | Moderate |
| D3 Tool Steel | 64 HRC | Exceptional | Lower |
| O1 Tool Steel | 60 HRC | Good | Good |
| 4140 Steel | 58 HRC | Good | Excellent |
| SKD12 | 62 HRC | Excellent | Excellent |
Available Surface Finishes
Raw Finishes
- Annealed Finish
- Ground Finish
- Precision Machined Finish
Functional Finishes
- Vacuum Hardened Finish
- Precision Ground Finish
- Nitrided Finish
- EDM Finish
Protective Finishes
- Black Oxide
- TiN Coating
- TiCN Coating
- DLC Coating
- Hard Chrome Plating
- PVD Coating
Frequently Asked Questions (FAQ)
What is A2 tool steel?
A2 is an air-hardening cold-work tool steel known for its excellent balance of toughness, wear resistance, and dimensional stability.
What is A2 steel used for?
Typical applications include:
- Punches
- Dies
- Shear Blades
- Gauges
- Fixtures
- Mold Components
What is the equivalent material to A2?
Common equivalents include:
- SKD12 (Japan)
- 1.2363 (Germany)
- Cr5Mo1V (China)
- X100CrMoV5 (Europe)
What is the difference between A2 and D2?
| Property | A2 | D2 |
|---|---|---|
| Toughness | Higher | Lower |
| Wear Resistance | Lower | Higher |
| Machinability | Better | Lower |
| Impact Resistance | Better | Moderate |
What hardness can A2 achieve?
- Hardened: 60–63 HRC
- Hardened & Tempered: 57–62 HRC
Is A2 suitable for punches and dies?
Yes. A2 is one of the most commonly used materials for punches, dies, and precision tooling.
Can A2 be nitrided?
Yes. Surface hardness can reach 65–72 HRC after nitriding.
Why is A2 preferred over D2 in some applications?
Because A2 provides:
- Better Toughness
- Improved Impact Resistance
- Easier Machining
- Lower Risk of Chipping
Is A2 suitable for precision tooling?
Yes. Its excellent dimensional stability makes it ideal for high-precision tooling applications.
Does GCNOV provide custom manufacturing services for A2 steel?
Yes. GCNOV provides:
- CNC Machining
- Tool & Die Manufacturing
- Wire EDM
- Precision Grinding
- Vacuum Heat Treatment
- Nitriding
- PVD Coating
- Prototype Development
- Low-Volume Production
- Mass Production