H13 Tool Steel: Properties and Key Applications
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H13 Tool Steel is a high-performance tool steel known for its exceptional toughness, wear resistance, and ability to withstand high temperatures. Classified as a hot work tool steel, H13 is primarily alloyed with chromium, molybdenum, and vanadium, which contribute to its unique properties. The chromium content enhances hardenability and corrosion resistance, while molybdenum improves strength and toughness at elevated temperatures. Vanadium is added to refine the grain structure, enhancing wear resistance.
Comprehensive Overview
H13 Tool Steel is widely used in applications requiring high strength and resistance to thermal fatigue. Its ability to maintain hardness and toughness at elevated temperatures makes it ideal for hot work applications, such as die casting and forging. The steel's excellent thermal conductivity and resistance to softening under heat contribute to its performance in demanding environments.
Advantages:
- High Toughness: H13 exhibits excellent toughness, reducing the risk of cracking during thermal cycling.
- Wear Resistance: The alloying elements provide superior wear resistance, making it suitable for high-impact applications.
- Heat Resistance: H13 maintains its hardness and strength at elevated temperatures, making it ideal for hot work tooling.
Limitations:
- Corrosion Resistance: While H13 has some resistance to corrosion, it is not as effective as stainless steels in highly corrosive environments.
- Machinability: H13 can be challenging to machine due to its hardness, requiring specialized tooling and techniques.
Historically, H13 has been a staple in the tool steel market, with applications in various industries, including automotive, aerospace, and manufacturing. Its versatility and performance have made it a preferred choice for many engineers and manufacturers.
Alternative Names, Standards, and Equivalents
| Standard Organization | Designation/Grade | Country/Region of Origin | Notes/Remarks |
|---|---|---|---|
| UNS | T20813 | USA | Closest equivalent to AISI H13 |
| AISI/SAE | H13 | USA | Commonly used designation |
| ASTM | A681 | USA | Specification for hot work tool steels |
| EN | 1.2344 | Europe | Equivalent grade in Europe |
| DIN | X40CrMoV5-1 | Germany | Minor compositional differences |
| JIS | SKD61 | Japan | Similar properties, often used interchangeably |
| GB | 4Cr5MoSiV1 | China | Equivalent with slight variations |
H13 is often compared to other tool steels like D2 and S7, which may have different wear resistance and toughness characteristics. Understanding these subtle differences is crucial for selecting the appropriate grade for specific applications.
Key Properties
Chemical Composition
| Element (Symbol and Name) | Percentage Range (%) |
|---|---|
| C (Carbon) | 0.32 - 0.45 |
| Cr (Chromium) | 4.75 - 5.50 |
| Mo (Molybdenum) | 1.10 - 1.75 |
| V (Vanadium) | 0.80 - 1.20 |
| Si (Silicon) | 0.80 - 1.20 |
| Mn (Manganese) | 0.20 - 0.60 |
| P (Phosphorus) | ≤ 0.03 |
| S (Sulfur) | ≤ 0.03 |
The primary alloying elements in H13 play critical roles:
- Chromium: Enhances hardenability and corrosion resistance.
- Molybdenum: Improves strength and toughness at high temperatures.
- Vanadium: Refines grain structure, enhancing wear resistance.
Mechanical Properties
| Property | Condition/Temper | Test Temperature | Typical Value/Range (Metric) | Typical Value/Range (Imperial) | Reference Standard for Test Method |
|---|---|---|---|---|---|
| Tensile Strength | Quenched & Tempered | Room Temp | 1,700 - 2,100 MPa | 247 - 304 ksi | ASTM E8 |
| Yield Strength (0.2% offset) | Quenched & Tempered | Room Temp | 1,500 - 1,800 MPa | 218 - 261 ksi | ASTM E8 |
| Elongation | Quenched & Tempered | Room Temp | 10 - 15% | 10 - 15% | ASTM E8 |
| Hardness (HRC) | Quenched & Tempered | Room Temp | 48 - 54 HRC | 48 - 54 HRC | ASTM E18 |
| Impact Strength | Quenched & Tempered | -20 °C | 20 - 30 J | 15 - 22 ft-lbf | ASTM E23 |
The combination of high tensile and yield strength, along with good elongation, makes H13 suitable for applications that experience significant mechanical loading and require structural integrity.
Physical Properties
| Property | Condition/Temperature | Value (Metric) | Value (Imperial) |
|---|---|---|---|
| Density | Room Temp | 7.85 g/cm³ | 0.284 lb/in³ |
| Melting Point/Range | - | 1,400 - 1,500 °C | 2,552 - 2,732 °F |
| Thermal Conductivity | Room Temp | 25 W/m·K | 14.5 BTU·in/h·ft²·°F |
| Specific Heat Capacity | Room Temp | 460 J/kg·K | 0.11 BTU/lb·°F |
| Electrical Resistivity | Room Temp | 0.0005 Ω·m | 0.0003 Ω·in |
| Coefficient of Thermal Expansion | Room Temp | 11.5 x 10⁻⁶/K | 6.4 x 10⁻⁶/°F |
Key physical properties such as thermal conductivity and melting point are significant for applications involving high temperatures, ensuring that H13 can perform effectively without losing its structural integrity.
Corrosion Resistance
| Corrosive Agent | Concentration (%) | Temperature (°C) | Resistance Rating | Notes |
|---|---|---|---|---|
| Chlorides | 5 - 10 | 25 - 60 | Fair | Risk of pitting corrosion |
| Sulfuric Acid | 10 - 30 | 25 - 50 | Poor | Not recommended |
| Acetic Acid | 5 - 20 | 25 - 60 | Fair | Susceptible to SCC |
| Atmospheric | - | - | Good | Moderate resistance |
H13 Tool Steel exhibits moderate corrosion resistance, making it suitable for certain environments but not ideal for highly corrosive applications. Compared to stainless steels like 304 or 316, H13 is less resistant to pitting and stress corrosion cracking, which can limit its use in specific applications.
Heat Resistance
| Property/Limit | Temperature (°C) | Temperature (°F) | Remarks |
|---|---|---|---|
| Max Continuous Service Temp | 500 | 932 | Suitable for prolonged exposure |
| Max Intermittent Service Temp | 600 | 1,112 | Short-term exposure without degradation |
| Scaling Temperature | 700 | 1,292 | Risk of oxidation above this temperature |
| Creep Strength considerations | 400 | 752 | Begins to degrade above this temperature |
H13 maintains its mechanical properties at elevated temperatures, making it suitable for hot work applications. However, care must be taken to avoid prolonged exposure to temperatures above its scaling limit, which can lead to oxidation and degradation.
Fabrication Properties
Weldability
| Welding Process | Recommended Filler Metal (AWS Classification) | Typical Shielding Gas/Flux | Notes |
|---|---|---|---|
| MIG | ER80S-D2 | Argon + CO2 mix | Preheat recommended |
| TIG | ER80S-D2 | Argon | Post-weld heat treatment |
| Stick | E7018 | - | Requires preheating |
H13 can be welded, but care must be taken to avoid cracking. Preheating and post-weld heat treatment are recommended to relieve stresses and ensure integrity.
Machinability
| Machining Parameter | H13 | AISI 1212 | Notes/Tips |
|---|---|---|---|
| Relative Machinability Index | 60% | 100% | Requires specialized tooling |
| Typical Cutting Speed (Turning) | 30 - 50 m/min | 80 - 120 m/min | Use carbide tools for best results |
H13 is more challenging to machine than lower alloy steels, requiring careful selection of cutting speeds and tooling to achieve optimal results.
Formability
H13 is not particularly suited for cold forming due to its hardness. Hot forming processes are preferred, allowing for better deformation without cracking. The steel exhibits work hardening, which can complicate cold forming operations.
Heat Treatment
| Treatment Process | Temperature Range (°C/°F) | Typical Soaking Time | Cooling Method | Primary Purpose / Expected Result |
|---|---|---|---|---|
| Annealing | 800 - 850 / 1,472 - 1,562 | 1 - 2 hours | Air | Reduce hardness, improve machinability |
| Quenching | 1,000 - 1,050 / 1,832 - 1,922 | 30 - 60 minutes | Oil | Achieve high hardness |
| Tempering | 500 - 600 / 932 - 1,112 | 1 - 2 hours | Air | Reduce brittleness, enhance toughness |
The heat treatment process significantly affects the microstructure of H13, transitioning it from austenite to martensite, which enhances its hardness and wear resistance.
Typical Applications and End Uses
| Industry/Sector | Specific Application Example | Key Steel Properties Utilized in this Application | Reason for Selection |
|---|---|---|---|
| Automotive | Die casting | High toughness, wear resistance | Durability under high stress |
| Aerospace | Forging dies | Heat resistance, strength at elevated temperatures | Performance in extreme conditions |
| Manufacturing | Hot stamping tools | Thermal fatigue resistance | Long tool life in production |
Other applications include:
- Injection molds
- Extrusion dies
- Metal forming tools
H13 is chosen for these applications due to its ability to withstand high temperatures and mechanical stresses, ensuring longevity and reliability in production processes.
Important Considerations, Selection Criteria, and Further Insights
| Feature/Property | H13 | D2 | S7 | Brief Pro/Con or Trade-off Note |
|---|---|---|---|---|
| Key Mechanical Property | High toughness | High wear resistance | High impact resistance | H13 offers a balance of toughness and wear resistance |
| Key Corrosion Aspect | Fair | Poor | Fair | H13 is better suited for less corrosive environments |
| Weldability | Moderate | Poor | Fair | H13 requires careful welding practices |
| Machinability | Challenging | Moderate | Good | H13 needs specialized tooling |
| Formability | Poor | Fair | Good | H13 is less formable than alternatives |
| Approx. Relative Cost | Moderate | Low | Moderate | Cost varies based on market conditions |
| Typical Availability | Common | Common | Less common | H13 is widely available in various forms |
When selecting H13, consider its performance characteristics in relation to the specific application requirements. While it offers excellent toughness and heat resistance, its machinability and corrosion resistance may limit its use in certain environments. Understanding these trade-offs is essential for optimizing material selection in engineering applications.