This article references the authoritative data from the Encyclopedia of Metal Materials and provides a detailed analysis of the performance characteristics and machining key points of Cr12MoV die steel. Cr12MoV is a high-carbon, high-chromium cold-work die steel that is widely known as the “King of Die Steels” for its excellent wear resistance, hardenability, and micro-deformation characteristics.
1. Basic Information on Cr12MoV
Cr12MoV (GB/T 1299-2014) is a high-carbon, high-chromium cold-work die steel. Molybdenum (Mo) and vanadium (V) are added on the basis of Cr12 to further refine the grain structure and improve toughness and wear resistance. This steel grade has excellent hardenability, can be hardened by oil quenching, and exhibits minimal heat treatment deformation. It is widely used to manufacture cold-work dies requiring high wear resistance, high precision, and mass production.
Domestic equivalent grade: Cr12MoV / Cr12Mo1V1
International approximate grades: D2 (AISI/SAE), 1.2379 (DIN/EN), SKD11 (JIS)
2. Chemical Composition (GB/T 1299-2014)
| Element | Content (%) | Function |
|---|---|---|
| Carbon (C) | 1.45–1.70 | Forms carbides, ensuring high hardness and wear resistance |
| Silicon (Si) | ≤0.40 | Deoxidizer, improves tempering stability |
| Manganese (Mn) | ≤0.40 | Improves hardenability |
| Chromium (Cr) | 11.00–12.50 | Forms a large number of chromium carbides, ensuring high wear resistance |
| Molybdenum (Mo) | 0.40–0.60 | Refines grain structure, improves toughness and tempering stability |
| Vanadium (V) | 0.15–0.30 | Refines grain structure, improves wear resistance |
| Phosphorus (P) | ≤0.030 | Impurity element, controlled content |
| Sulfur (S) | ≤0.030 | Impurity element, controlled content |
3. Mechanical Properties
| Performance Indicator | Value | Condition |
|---|---|---|
| Hardness (annealed state) | ≤255 HBW | After annealing |
| Hardness (quenched + low-temperature tempering) | ≥60 HRC | Oil quenching at 1000–1050°C + tempering at 150–200°C |
| Hardness (quenched + high-temperature tempering) | 58–62 HRC | Oil quenching at 1000–1050°C + tempering at 500–520°C |
| Compressive strength | ≥2500 MPa | Quenched + low-temperature tempering |
| Impact toughness | ≥15 J/cm² | Quenched + tempered |
4. Heat Treatment Process
Heat treatment process characteristics of Cr12MoV:
- Spheroidizing annealing: Heat at 850–870°C, furnace cool to 730–750°C, hold isothermally for 3–4h, furnace cool to below 500°C, then air cool
- Quenching temperature: 1000–1050°C (primary hardening) / 1100–1150°C (secondary hardening)
- Cooling medium: Oil quenching or air cooling, excellent hardenability
- Tempering temperature: Low-temperature tempering at 150–200°C (62–64 HRC) / high-temperature tempering at 500–520°C (58–62 HRC, secondary hardening)
- Cryogenic treatment: After quenching, cryogenic treatment at –70 to –80°C for 2–4h, which further transforms retained austenite into martensite, improving dimensional stability
- Heat treatment deformation: Cr12MoV is a micro-deformation steel, with a typical volume change of approximately 0.1%–0.2% during conventional quenching
5. Typical Applications
- Cold stamping dies: Blanking dies, blanking dies, fine blanking dies, cold extrusion dies
- Cold heading dies: Cold heading dies, thread rolling flat dies, thread rolling cylindrical dies
- Drawing dies: Wire drawing dies, tube drawing dies
- Plastic molds: High-wear-resistant injection molds, thermosetting plastic molds
- Measuring tools and precision parts: Gauges, plug gauges, high-precision CNC-machined wear-resistant parts
- Powder metallurgy molds: Compact forming dies
6. CNC Machining Performance
CNC machining characteristics of Cr12MoV:
- Cutting in annealed state: Hardness ≤255 HBW, machinability is below average, carbide tools with low-speed rough machining are recommended
- Machining in hardened state: Hardness ≥58 HRC, conventional tools are difficult to cut, CBN tools or grinding are required
- Recommended cutting speed: Annealed state 40–80 m/min (carbide); hardened state requires grinding or low-speed CBN cutting
- Tool selection: Carbide K/P grades for rough machining, CBN tools for finishing, TiAlN-coated carbide drills for drilling
- Coolant: Water-soluble cutting fluid with extreme-pressure additives is recommended
- Precautions: The chromium carbide particles in Cr12MoV have extremely high hardness (HV 1200–1600), resulting in high cutting forces, rapid tool wear, and the machining allowance needs to be reasonably allocated
7. Procurement Guide
Supply forms: Hot-rolled plates, forgings, round bars, flat steel, blocks
Delivery condition: Annealed state (≤255 HBW)
Acceptance standard: GB/T 1299-2014 Tool and Die Steels
Common specifications:
- Round bars: φ10–φ300 mm
- Plates: thickness 10–200 mm
- Blocks: customized according to drawings
8. Summary
As a classic cold-work die steel, Cr12MoV is based on high carbon and high chromium, strengthened through Mo-V microalloying, and delivers outstanding performance in wear resistance, hardenability, and dimensional stability. A reasonable heat treatment process and machining strategy are the keys to maximizing its performance. Selecting the right supplier and following standardized process procedures are essential to ensure that die life and product quality meet expectations.
Data sources: GB/T 1299-2014 Tool and Die Steels, GB/T 228.1-2010 Metallic Materials – Tensile Testing Method, Encyclopedia of Metal Materials database
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