Maraging 300 Steel: Properties and Key Applications
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Table Of Content
Table Of Content
Maraging 300 Steel (C300/M300) is a high-strength, low-carbon steel that belongs to the family of maraging steels. It is primarily classified as a low-carbon alloy steel, notable for its unique combination of strength, toughness, and ductility. The primary alloying elements in Maraging 300 include nickel, cobalt, molybdenum, and titanium, which contribute significantly to its mechanical properties and overall performance.
Comprehensive Overview
Maraging 300 Steel is characterized by its exceptional strength and toughness, achieved through a unique aging process that transforms the steel's microstructure. The low carbon content minimizes the risk of brittleness, while the high nickel content enhances its hardenability. The addition of cobalt and molybdenum further improves its strength and resistance to wear, making it suitable for demanding applications.
The most significant characteristics of Maraging 300 include:
- High Yield Strength: Typically exceeding 2,000 MPa (290 ksi), making it ideal for applications requiring high load-bearing capacity.
- Excellent Toughness: Retains toughness even at low temperatures, which is critical for applications in extreme environments.
- Good Weldability: Can be welded using standard techniques, although preheating and post-weld treatments are recommended to avoid cracking.
Advantages and Limitations
| Advantages | Limitations |
|---|---|
| Exceptional strength-to-weight ratio | Higher cost compared to conventional steels |
| Good ductility and toughness | Limited corrosion resistance in certain environments |
| Excellent machinability | Requires careful heat treatment to achieve desired properties |
Maraging 300 is commonly used in aerospace, tooling, and high-performance applications due to its superior mechanical properties. Historically, it has played a significant role in the development of advanced materials for critical engineering applications.
Alternative Names, Standards, and Equivalents
| Standard Organization | Designation/Grade | Country/Region of Origin | Notes/Remarks |
|---|---|---|---|
| UNS | K93120 | USA | Closest equivalent to AISI 300M |
| AISI/SAE | 300M | USA | Minor compositional differences to be aware of |
| ASTM | A787 | USA | Standard specification for maraging steels |
| EN | 1.6350 | Europe | Equivalent grade with similar properties |
| JIS | SCS14 | Japan | Similar performance but with different alloying elements |
The differences between these grades can affect performance in specific applications, particularly in terms of strength and corrosion resistance. For instance, while both K93120 and 300M offer high strength, the specific heat treatment processes may yield different toughness levels.
Key Properties
Chemical Composition
| Element (Symbol and Name) | Percentage Range (%) |
|---|---|
| Ni (Nickel) | 17.0 - 19.0 |
| Co (Cobalt) | 8.0 - 9.0 |
| Mo (Molybdenum) | 4.0 - 5.0 |
| Ti (Titanium) | 0.5 - 1.0 |
| C (Carbon) | ≤ 0.03 |
| Fe (Iron) | Balance |
The primary alloying elements in Maraging 300 play crucial roles in its performance:
- Nickel: Enhances hardenability and strength.
- Cobalt: Improves high-temperature strength and hardness.
- Molybdenum: Increases resistance to softening at elevated temperatures.
- Titanium: Aids in grain refinement and contributes to strength.
Mechanical Properties
| Property | Condition/Temper | Test Temperature | Typical Value/Range (Metric) | Typical Value/Range (Imperial) | Reference Standard for Test Method |
|---|---|---|---|---|---|
| Tensile Strength | Annealed | Room Temp | 2,000 - 2,200 MPa | 290 - 320 ksi | ASTM E8 |
| Yield Strength (0.2% offset) | Annealed | Room Temp | 1,800 - 2,000 MPa | 261 - 290 ksi | ASTM E8 |
| Elongation | Annealed | Room Temp | 10 - 15% | 10 - 15% | ASTM E8 |
| Hardness (Rockwell C) | Annealed | Room Temp | 40 - 45 HRC | 40 - 45 HRC | ASTM E18 |
| Impact Strength (Charpy) | Annealed | -196 °C | 50 - 70 J | 37 - 52 ft-lbf | ASTM E23 |
The combination of these mechanical properties makes Maraging 300 particularly suitable for applications requiring high strength and toughness, such as aerospace components and tooling.
Physical Properties
| Property | Condition/Temperature | Value (Metric) | Value (Imperial) |
|---|---|---|---|
| Density | Room Temp | 8.0 g/cm³ | 0.289 lb/in³ |
| Melting Point | - | 1,400 °C | 2,552 °F |
| Thermal Conductivity | Room Temp | 20 W/m·K | 13 BTU·in/h·ft²·°F |
| Specific Heat Capacity | Room Temp | 500 J/kg·K | 0.119 BTU/lb·°F |
| Electrical Resistivity | Room Temp | 0.7 µΩ·m | 0.0000007 Ω·m |
The practical significance of the density and melting point of Maraging 300 is crucial for applications in aerospace, where weight savings are paramount, and components must withstand high temperatures without deformation.
Corrosion Resistance
| Corrosive Agent | Concentration (%) | Temperature (°C) | Resistance Rating | Notes |
|---|---|---|---|---|
| Chlorides | 3-10 | 20-60 | Fair | Risk of pitting corrosion |
| Sulfuric Acid | 10-30 | 20-40 | Poor | Not recommended |
| Sea Water | - | 20-30 | Good | Moderate resistance |
Maraging 300 exhibits moderate resistance to corrosion, particularly in chloride environments, but is susceptible to pitting and stress corrosion cracking. Compared to stainless steels like 316L, which offer excellent corrosion resistance, Maraging 300 may require protective coatings or surface treatments in aggressive environments.
Heat Resistance
| Property/Limit | Temperature (°C) | Temperature (°F) | Remarks |
|---|---|---|---|
| Max Continuous Service Temp | 300 °C | 572 °F | Suitable for high-temperature applications |
| Max Intermittent Service Temp | 400 °C | 752 °F | Can withstand short-term exposure to higher temperatures |
| Scaling Temperature | 600 °C | 1,112 °F | Risk of oxidation beyond this temperature |
At elevated temperatures, Maraging 300 maintains its strength and hardness but may experience oxidation. Proper heat treatment can enhance its performance in high-temperature applications.
Fabrication Properties
Weldability
| Welding Process | Recommended Filler Metal (AWS Classification) | Typical Shielding Gas/Flux | Notes |
|---|---|---|---|
| TIG | ERNiCrMo-3 | Argon | Preheat recommended |
| MIG | ERNiCrMo-3 | Argon/CO2 | Post-weld heat treatment needed |
Maraging 300 is weldable using standard techniques, but preheating and post-weld heat treatment are essential to prevent cracking and ensure optimal mechanical properties.
Machinability
| Machining Parameter | Maraging 300 | AISI 1212 | Notes/Tips |
|---|---|---|---|
| Relative Machinability Index | 70 | 100 | Requires high-speed tooling |
| Typical Cutting Speed (Turning) | 50 m/min | 80 m/min | Use carbide tools for best results |
Maraging 300 exhibits good machinability, but care must be taken to use appropriate cutting speeds and tooling to avoid work hardening.
Formability
Maraging 300 is suitable for both cold and hot forming processes. However, due to its high strength, it may require higher forces during forming operations. The material exhibits good ductility, allowing for complex shapes to be formed without cracking.
Heat Treatment
| Treatment Process | Temperature Range (°C/°F) | Typical Soaking Time | Cooling Method | Primary Purpose / Expected Result |
|---|---|---|---|---|
| Solution Annealing | 820-850 °C / 1,508-1,562 °F | 1-2 hours | Air Cooling | Dissolves precipitates, refines grain structure |
| Aging | 480-500 °C / 896-932 °F | 4-8 hours | Air Cooling | Increases strength through precipitation hardening |
The heat treatment processes significantly influence the microstructure of Maraging 300, enhancing its mechanical properties and ensuring optimal performance in applications.
Typical Applications and End Uses
| Industry/Sector | Specific Application Example | Key Steel Properties Utilized in this Application | Reason for Selection |
|---|---|---|---|
| Aerospace | Aircraft landing gear | High strength, toughness | Critical load-bearing application |
| Tooling | Molds for injection molding | High wear resistance, machinability | Precision and durability required |
| Automotive | High-performance components | Lightweight, high strength | Performance enhancement |
Other applications include:
-
- High-speed tooling
-
- Structural components in aerospace
-
- Sports equipment (e.g., golf clubs)
Maraging 300 is chosen for these applications due to its unique combination of high strength, toughness, and machinability, making it ideal for components that must withstand extreme conditions.
Important Considerations, Selection Criteria, and Further Insights
| Feature/Property | Maraging 300 | AISI 4340 | 17-4 PH | Brief Pro/Con or Trade-off Note |
|---|---|---|---|---|
| Key Mechanical Property | High strength | Moderate strength | High strength | Maraging 300 offers superior toughness |
| Key Corrosion Aspect | Fair | Good | Excellent | 17-4 PH is better for corrosion resistance |
| Weldability | Good | Fair | Good | Maraging 300 is easier to weld than 4340 |
| Machinability | Good | Fair | Good | Maraging 300 is easier to machine than 4340 |
| Approx. Relative Cost | High | Moderate | High | Cost considerations may limit use |
| Typical Availability | Moderate | High | High | Availability can affect project timelines |
When selecting Maraging 300, considerations include its cost-effectiveness, availability, and specific performance requirements. While it offers exceptional mechanical properties, its higher cost compared to conventional steels may limit its use to specialized applications. Additionally, its magnetic properties make it suitable for applications requiring non-magnetic materials.
In summary, Maraging 300 Steel is a high-performance material that excels in applications demanding strength, toughness, and machinability. Its unique properties make it a preferred choice in aerospace, tooling, and high-performance engineering sectors.