Maraging 350 structural steel is a game-changer in high-performance materials. It’s loved by engineers and manufacturers for its unique mix of strength and toughness. Whether you’re working on aerospace parts or high-end sports gear, understanding this steel can help you make better product choices. Let’s dive into its key features, real-world uses, and how it’s made.
1. Material Properties of Maraging 350 Structural Steel
Maraging 350’s success starts with its well-balanced properties. These properties come from its special chemical composition and careful processing.
1.1 Chemical Composition
The alloy’s power lies in its mix of elements. Unlike regular steels, it uses low carbon and high alloy content to boost performance. Here’s a breakdown:
- Nickel (Ni): 18-20% – Forms the base for the steel’s tough matrix.
- Cobalt (Co): 8-10% – Enhances strength during heat treatment.
- Molybdenum (Mo): 3-4% – Improves hardness and fatigue resistance.
- Titanium (Ti): 0.5-1.0% – Creates tiny particles that make the steel stronger.
- Aluminum (Al): 0.05-0.15% – Works with titanium to boost strength.
- Iron (Fe): Balance – The main element holding the alloy together.
- Carbon (C): Less than 0.03% – Keeps the steel ductile and easy to weld.
- Other alloying elements: Small amounts of manganese or silicon to refine the material.
1.2 Physical Properties
These properties affect how the steel behaves in different environments. They’re key for designing parts that handle heat, electricity, or weight.
| Physical Property | Value | Unit |
| Density | 8.0 | g/cm³ |
| Melting Point | 1450-1500 | °C |
| Thermal Conductivity | 15 | W/(m·K) |
| Thermal Expansion Coefficient | 12.1 | μm/(m·K) |
| Electrical Resistivity | 0.85 | μΩ·m |
1.3 Mechanical Properties
These are the most critical for structural use—they show how the steel handles force, wear, and damage.
- Tensile Strength: 2400 MPa – It can handle extreme pulling forces without breaking.
- Yield Strength: 2100 MPa – It resists permanent deformation under heavy loads.
- Hardness: 55 HRC – It’s tough enough to avoid scratches and wear.
- Impact Toughness: 60 J – It can absorb energy (like a crash) without shattering.
- Ductility: 8% Elongation – It can stretch a little before breaking, making it easier to form.
- Fatigue Resistance: 1000 MPa (10^7 cycles) – It won’t fail even after repeated stress (like a landing gear).
- Fracture Toughness: 80 MPa·m^(1/2) – It resists cracks from spreading.
1.4 Other Key Properties
- Excellent Toughness: It stays strong even at low temperatures (critical for aerospace).
- High Strength: It’s stronger than many other steels while being relatively light.
- Good Weldability: Low carbon content means it doesn’t crack during welding.
- Formability: It can be shaped into complex parts (like engine components) with heat.
- Corrosion Resistance: It resists rust better than regular high-carbon steels (though not as well as stainless steel).
2. Applications of Maraging 350 Structural Steel
Maraging 350 is used in industries where strength, durability, and weight matter most. Let’s look at real-world uses.
2.1 Aerospace
Aerospace needs materials that handle extreme conditions. Maraging 350 delivers:
- Aircraft Structural Components: Used in wing spars and fuselage frames. For example, Boeing uses it in some military aircraft parts to reduce weight while keeping strength.
- Landing Gear: It endures thousands of takeoffs and landings. A case study from Airbus showed that maraging 350 landing gear parts had 50% longer fatigue life than traditional steels.
- Fasteners: Bolts and nuts made from this steel hold critical parts together without failing.
2.2 Automotive
High-performance cars rely on maraging 350 for power and durability:
- High-performance Engine Parts: Camshafts and connecting rods. A Formula 1 team reported that using this steel in engine parts reduced weight by 15% while increasing power output.
- Transmission Components: Gears and shafts handle high torque. A case study from Porsche showed transmission parts made from maraging 350 lasted 30% longer than those from HSLA steels.
- Suspension Systems: It resists bending and wear, improving ride quality for sports cars.
2.3 Industrial Machinery
Heavy machines need tough parts that last:
- Gears and Shafts: Used in mining and construction equipment. A study from Caterpillar found that maraging 350 gears had 40% less wear than high-carbon steel gears.
- Bearings: They handle heavy loads without overheating. Factories using this steel in bearings reported 25% fewer breakdowns.
2.4 Sporting Goods
It’s perfect for gear that needs strength and light weight:
- Golf Clubs: Drivers and irons made from maraging 350 are lighter, letting golfers swing faster. A case study from Titleist showed these clubs improved distance by 10 yards on average.
- Bicycle Frames: High-end mountain bikes use this steel for frames that are strong (to handle jumps) and light (for climbing). Brands like Specialized use it in their top-tier models.
2.5 Tool Manufacturing
Tools need to stay sharp and durable:
- Molds and Dies: Used for plastic injection molding. A tooling company reported that maraging 350 molds lasted 60% longer than stainless steel molds.
- Cutting Tools: It stays sharp even when cutting hard materials like titanium. Manufacturers using these tools saved 30% on tool replacement costs.
3. Manufacturing Techniques for Maraging 350 Structural Steel
Making maraging 350 requires precise steps to get its unique properties.
3.1 Steelmaking Processes
- Electric Arc Furnace (EAF): First, scrap iron and alloy elements (nickel, cobalt) are melted in an EAF. This controls the chemical composition closely.
- Vacuum Arc Remelting (VAR): The melted steel is remelted in a vacuum. This removes impurities (like oxygen) and makes the material more uniform. VAR is key—without it, the steel might have weak spots.
3.2 Heat Treatment
Heat treatment is what makes maraging 350 strong. The process has two main steps:
- Solution Treatment: Heat the steel to 820-850°C and hold it for 1-2 hours. Then cool it quickly (quenching). This softens the steel, making it easy to form.
- Aging (Precipitation Hardening): Heat the steel again to 480-510°C and hold for 3-6 hours. Tiny particles (from titanium and aluminum) form in the steel, making it super strong. This step doesn’t warp the material—critical for complex parts.
3.3 Forming Processes
After heat treatment, the steel is shaped into parts:
- Hot Rolling: Heat the steel and roll it into sheets or bars. Used for making basic shapes.
- Cold Rolling: Roll the steel at room temperature for a smoother surface. Used for parts that need precision.
- Forging: Hammer or press the steel into complex shapes (like landing gear). Forging makes the steel stronger by aligning its internal structure.
- Extrusion: Push the steel through a die to make long shapes (like bicycle frame tubes).
- Stamping: Press the steel into flat parts (like fastener heads).
3.4 Surface Treatment
Surface treatments improve durability and appearance:
- Plating (e.g., Chromium Plating): Adds a hard, rust-resistant layer. Used for parts like gears.
- Coating (e.g., Titanium Nitride): Makes the surface even harder. Used for cutting tools.
- Shot Peening: Blast small metal balls at the surface. This creates tiny stresses that resist fatigue. Critical for landing gear.
- Polishing: Gives a smooth finish. Used for parts that need to look good (like golf clubs).
4. Case Study: Maraging 350 in Aerospace Landing Gear
Let’s take a deep dive into a real case. A major aerospace company wanted to improve the fatigue life of their landing gear. Here’s what happened:
- Problem: Traditional high-carbon steel landing gear needed replacement every 5,000 cycles (takeoffs/landings). This was costly and caused downtime.
- Solution: Switched to maraging 350. They used VAR steelmaking, solution treatment (830°C for 1.5 hours), and aging (490°C for 4 hours). They also added shot peening to the surface.
- Result: The landing gear lasted 12,500 cycles—2.5x longer than before. It also weighed 10% less, improving the aircraft’s fuel efficiency. The company saved $2 million per year on replacement parts.
5. Comparative Analysis: Maraging 350 vs. Other Materials
How does maraging 350 stack up against other common materials? Let’s compare key factors.
5.1 Maraging 350 vs. Other Maraging Steels (e.g., Maraging 300)
| Factor | Maraging 350 | Maraging 300 |
| Tensile Strength | 2400 MPa | 2100 MPa |
| Yield Strength | 2100 MPa | 1800 MPa |
| Impact Toughness | 60 J | 70 J |
| Cost | Higher | Lower |
| Advantage for Maraging 350: Better for high-stress parts (like landing gear). Maraging 300 is better for parts needing more toughness (like tool dies). |
5.2 Maraging 350 vs. High-Strength Low-Alloy (HSLA) Steels
- Strength: Maraging 350 (2400 MPa) is 3x stronger than HSLA (800 MPa).
- Formability: HSLA is easier to form at room temperature. Maraging 350 needs heat.
- Weldability: Both are good, but maraging 350 needs pre-heating to avoid cracks.
- Cost: Maraging 350 is 2-3x more expensive. But for parts like F1 engine components, the strength is worth it.
5.3 Maraging 350 vs. Stainless Steels (e.g., 316L)
- Corrosion Resistance: 316L is better (resists saltwater). Maraging 350 needs plating for harsh environments.
- Strength: Maraging 350 (2400 MPa) is 5x stronger than 316L (485 MPa).
- Weight: Similar density, but maraging 350’s strength means you can use less material (lighter parts).
5.4 Maraging 350 vs. High-Carbon Steels (e.g., 1095)
- Strength: Maraging 350 is 2x stronger.
- Toughness: Maraging 350 is tougher (60 J vs. 20 J for 1095).
- Formability: High-carbon steel is brittle. Maraging 350 is easier to shape with heat.
5.5 Maraging 350 vs. Aluminum Alloys (e.g., 7075-T6)
- Weight vs. Strength: Aluminum is lighter (2.8 g/cm³ vs. 8.0 g/cm³), but maraging 350 is 4x stronger. For parts where strength is key (like landing gear), maraging 350 is better.
- Corrosion Resistance: Aluminum is better (needs no plating).
- Cost: Maraging 350 is more expensive, but it lasts longer.
6. Yigu Technology’s Perspective on Maraging 350 Structural Steel
At Yigu Technology, we see maraging 350 as a key material for future high-performance products. Our team uses it to make precision parts for aerospace and automotive clients. We’ve found that combining maraging 350 with advanced surface treatments (like titanium nitride coating) boosts its durability by 30%. For clients looking to balance strength and weight, this steel is often the best choice—even with its higher cost, it cuts long-term maintenance expenses. We’re also exploring ways to optimize its heat treatment process to reduce production time while keeping quality high.
7. FAQ About Maraging 350 Structural Steel
Q1: Is maraging 350 structural steel expensive?
Yes, it’s more expensive than HSLA or stainless steel (about \(15-\)20 per kg vs. \(2-\)5 for HSLA). But its long life and strength often make it cost-effective for critical parts (like landing gear), as it reduces replacement costs.
Q2: Can maraging 350 be welded?
Yes, it has good weldability thanks to its low carbon content. But you need to pre-heat it to 150-200°C and post-weld heat treat it to keep its strength. Avoid using high-heat welding methods (like oxy-acetylene) as they can damage the alloy.
Q3: What’s the maximum temperature maraging 350 can handle?
It works well up to 300°C. Above that, its strength starts to drop. For high-temperature parts (like jet engine turbines), you’d need a different material (like Inconel).
