Overview
SKD61 Tool Steel is a premium chromium-molybdenum-vanadium hot work tool steel specified under JIS G4404, widely recognized as the Japanese equivalent of AISI H13 and DIN 1.2344. It is renowned for its exceptional combination of hot hardness, thermal fatigue resistance, wear resistance, toughness, and dimensional stability.
SKD61 is considered the industry-standard material for:
- Aluminum Die Casting Dies
- Plastic Injection Molds
- Hot Forging Dies
- Extrusion Dies
- Hot Shear Blades
- Die Casting Inserts
- Aerospace Tooling
- High-Temperature Manufacturing Equipment
Its excellent resistance to heat checking and thermal cracking makes SKD61 one of the most widely used hot-work tool steels in Asia and globally.
Material Specification
| Property | Value |
|---|---|
| Material Designation | SKD61 |
| Standard | JIS G4404 |
| Material Family | Chromium Hot Work Tool Steel |
| Density | 7.80 g/cm³ |
| Magnetic Property | Magnetic |
| Typical Supply Condition | Annealed, Pre-Hardened |
| Standard Forms | Round Bar, Plate, Block, Forgings |
Chemical Composition
| Element | Content (%) |
|---|---|
| Iron (Fe) | Balance |
| Carbon (C) | 0.32–0.42 |
| Chromium (Cr) | 4.80–5.50 |
| Molybdenum (Mo) | 1.00–1.50 |
| Vanadium (V) | 0.80–1.20 |
| Silicon (Si) | 0.80–1.20 |
| Manganese (Mn) | 0.20–0.50 |
| Phosphorus (P) | ≤0.030 |
| Sulfur (S) | ≤0.030 |
The chromium, molybdenum, and vanadium alloy system provides excellent hot strength, temper resistance, and thermal fatigue performance.
Mechanical Properties
Annealed Condition
| Property | Value |
|---|---|
| Tensile Strength | 800–1000 MPa |
| Yield Strength | 600–800 MPa |
| Hardness | 180–235 HB |
| Elastic Modulus | 210 GPa |
Hardened & Tempered Condition
| Property | Value |
|---|---|
| Hardness | 44–54 HRC |
| Toughness | Excellent |
| Wear Resistance | Excellent |
| Thermal Fatigue Resistance | Outstanding |
High Temperature Condition
| Property | Value |
|---|---|
| Hot Hardness | Outstanding |
| Heat Checking Resistance | Outstanding |
| Thermal Shock Resistance | Excellent |
| Service Life | Exceptional |
Physical Properties
| Property | Value |
|---|---|
| Density | 7.80 g/cm³ |
| Melting Point | 1420–1460°C |
| Thermal Conductivity | 28 W/m·K |
| Electrical Resistivity | 0.55 μΩ·m |
| Thermal Expansion Coefficient | 11.7 × 10⁻⁶/K |
| Specific Heat Capacity | 460 J/kg·K |
Corrosion Resistance
| Environment | Performance |
|---|---|
| Indoor Environment | Moderate |
| Dry Atmosphere | Good |
| Humid Environment | Moderate |
| Outdoor Environment | Moderate |
| Marine Environment | Poor |
| Chemical Environment | Poor |
SKD61 is not a stainless steel and should be protected in corrosive environments.
Recommended surface treatments:
- Gas Nitriding
- Ion Nitriding
- PVD Coating
- TiN Coating
- CrN Coating
- QPQ Treatment
- Hard Chrome Plating
Weldability
| Welding Process | Rating |
|---|---|
| TIG Welding | Good |
| MIG Welding | Good |
| Arc Welding | Good |
| Laser Repair Welding | Excellent |
| Mold Repair Welding | Excellent |
SKD61 is widely used in mold repair applications because of its excellent weldability.
Recommended:
- Preheat: 300–450°C
- Controlled Cooling
- Post-Weld Tempering
Machinability
| Process | Rating |
|---|---|
| CNC Turning | Good |
| CNC Milling | Good |
| Drilling | Good |
| Grinding | Excellent |
| EDM Machining | Excellent |
| Wire EDM | Excellent |
Machinability Comparison
| Material | Machinability |
|---|---|
| P20 Mold Steel | Excellent |
| SKD61 | Good |
| H13 | Good |
| SKD11 | Fair |
| D2 | Fair |
SKD61 is frequently supplied in pre-hardened condition for mold production.
Heat Treatment
Annealing
| Parameter | Value |
|---|---|
| Temperature | 840–870°C |
| Cooling Method | Furnace Cool |
Preheating
| Parameter | Value |
|---|---|
| Temperature | 800–850°C |
Hardening
| Parameter | Value |
|---|---|
| Temperature | 1020–1050°C |
| Cooling Medium | Air, Vacuum, or Oil |
Tempering
| Parameter | Value |
|---|---|
| Temperature | 540–650°C |
| Cycles | Double or Triple Temper Recommended |
Hardness After Heat Treatment
| Condition | Hardness |
|---|---|
| Annealed | 180–235 HB |
| Hardened | 52–56 HRC |
| Hardened & Tempered | 44–54 HRC |
Nitriding
| Property | Value |
|---|---|
| Surface Hardness | 900–1200 HV |
| Case Depth | 0.10–0.60 mm |
| Wear Resistance | Outstanding |
International Equivalent Grades
| Standard | Equivalent Grade |
|---|---|
| JIS (Japan) | SKD61 |
| ASTM / AISI (USA) | H13 |
| DIN (Germany) | 1.2344 |
| EN (Europe) | X40CrMoV5-1 |
| GB/T (China) | 4Cr5MoSiV1 |
| ISO | X40CrMoV5-1 |
| UNS | T20813 |
Available Forms
| Product Type | Availability |
|---|---|
| Round Bar | Yes |
| Tool Steel Plate | Yes |
| Mold Blocks | Yes |
| Forgings | Yes |
| Pre-Hardened Blocks | Yes |
| Precision Ground Stock | Yes |
Typical Applications
Die Casting Industry
- Aluminum Die Casting Dies
- Zinc Die Casting Dies
- Magnesium Die Casting Dies
- Die Inserts
Plastic Mold Industry
- Injection Mold Cavities
- Mold Cores
- Hot Runner Components
- Mold Inserts
Forging Industry
- Hot Forging Dies
- Press Forging Dies
- Hammer Dies
- Upsetting Dies
Extrusion Industry
- Aluminum Extrusion Dies
- Copper Extrusion Tooling
- Mandrels
- Tool Holders
Aerospace Industry
- Hot Forming Tooling
- Precision Forging Dies
- Structural Component Molds
General Engineering
- Hot Shear Blades
- Hot Punches
- High-Temperature Wear Components
Manufacturing Characteristics
| Manufacturing Process | Rating |
|---|---|
| CNC Machining | Excellent |
| Precision Grinding | Outstanding |
| EDM Machining | Excellent |
| Wire EDM | Excellent |
| Heat Treatment | Outstanding |
| Nitriding | Outstanding |
| Mold Repair Welding | Outstanding |
Advantages
Outstanding Hot Hardness
Maintains hardness and strength at elevated temperatures.
Exceptional Thermal Fatigue Resistance
Excellent resistance to heat checking and thermal cracking.
Excellent Wear Resistance
Suitable for long production runs.
Good Toughness
Provides a balance between wear resistance and crack resistance.
Excellent Hardenability
Suitable for large mold and die sections.
Long Tool Life
Industry-standard material for high-volume die casting and molding.
Limitations
Moderate Corrosion Resistance
Requires protective coatings.
Higher Cost Than P20
Premium alloy content increases material cost.
Requires Proper Heat Treatment
Performance depends heavily on heat-treatment quality.
Lower Toughness Than H11
May not be ideal for extreme impact applications.
Comparison with Other Tool Steels
| Property | SKD61 | H13 | H11 | SKD11 | P20 |
|---|---|---|---|---|---|
| Hot Hardness | Outstanding | Outstanding | Excellent | Poor | Poor |
| Wear Resistance | Excellent | Excellent | Good | Outstanding | Moderate |
| Toughness | Excellent | Excellent | Higher | Moderate | Good |
| Thermal Fatigue Resistance | Outstanding | Outstanding | Excellent | Poor | Poor |
| Mold Applications | Outstanding | Outstanding | Excellent | Limited | Excellent |
Comparison with Mold Steels
| Material | Hardness | Thermal Fatigue Resistance | Mold Life |
|---|---|---|---|
| SKD61 | 44–54 HRC | Outstanding | Exceptional |
| H13 | 44–54 HRC | Outstanding | Exceptional |
| H11 | 44–52 HRC | Excellent | Excellent |
| P20 | 28–34 HRC | Moderate | Good |
| S136 | 48–52 HRC | Good | Excellent |
Available Surface Finishes
Raw Finishes
- Annealed Finish
- Forged Finish
- Ground Finish
- Precision Machined Finish
Functional Finishes
- Hardened Finish
- Nitrided Finish
- Precision Ground Finish
- EDM Finish
Protective Finishes
- Gas Nitriding
- QPQ Treatment
- TiN Coating
- CrN Coating
- PVD Coating
- Hard Chrome Plating
Frequently Asked Questions (FAQ)
What is SKD61 tool steel?
SKD61 is a Japanese hot-work tool steel equivalent to H13, widely used in die casting, plastic molding, and hot forging applications.
What is SKD61 used for?
Typical applications include:
- Die Casting Dies
- Plastic Injection Molds
- Forging Dies
- Extrusion Dies
- Hot Shear Blades
What is the equivalent material to SKD61?
Common equivalents include:
- H13 (USA)
- DIN 1.2344 (Germany)
- X40CrMoV5-1 (Europe)
- 4Cr5MoSiV1 (China)
Is SKD61 the same as H13?
Yes. SKD61 and H13 are generally considered direct equivalents for industrial applications.
What hardness can SKD61 achieve?
Typically:
- Hardened: 52–56 HRC
- Hardened & Tempered: 44–54 HRC
Is SKD61 suitable for die casting?
Yes. It is one of the most widely used materials for aluminum and zinc die casting dies.
Can SKD61 be nitrided?
Yes. Nitriding significantly improves wear resistance and extends mold life.
What is the difference between SKD61 and SKD11?
| Property | SKD61 | SKD11 |
|---|---|---|
| Application | Hot Work | Cold Work |
| Hot Hardness | Excellent | Poor |
| Wear Resistance | Excellent | Outstanding |
| Thermal Fatigue Resistance | Outstanding | Poor |
| Die Casting Use | Yes | No |
Why is SKD61 widely used in mold manufacturing?
Because it combines:
- High Hot Hardness
- Excellent Thermal Fatigue Resistance
- Good Toughness
- Long Mold Life
- Reliable Heat Treatment Performance
Does GCNOV provide custom manufacturing services for SKD61 steel?
Yes. GCNOV provides:
- CNC Machining
- Mold Manufacturing
- Die Manufacturing
- EDM Processing
- Precision Grinding
- Heat Treatment
- Nitriding
- Mold Repair Welding
- Prototype Development
- Low-Volume Production
- Mass Production