Maraging steel is a type of ultra-high strength steel. It is an ultra-high-strength maraging steel with carbon-free (or micro-carbon) martensite as the matrix, which can produce precipitation hardening of intermetallic compounds during aging. Unlike traditional high-strength steels, it does not use carbon but is strengthened by the precipitation of intermetallic compounds. This gives it some unique properties: high strength and toughness, low hardening index, good formability, simple heat treatment process, little deformation during aging, and very good weldability. Therefore, maraging steel has been widely used in sectors that require such properties.
The outstanding advantage of this kind of steel is that the heat treatment process is simple and convenient. After solid solution, it is first machined and then aged. The heat treatment deformation is small, and the processing performance and welding performance are very good. The heat treatment process and properties of maraging steel are shown in the table below.
| Maraging Steel Data | C200/18Ni(200) | C250/18Ni(250) | C300/18Ni(300) | C350/18Ni(350) |
|---|---|---|---|---|
| Solution temperature | 815 – 830 ℃ | 815 ℃ | 816 ℃ | 816 ℃ |
| Aging temperature | 475 – 485 ℃ | 482 ℃ | 482 ℃ | 510 ℃ |
| Hardness | 34 HRC | 50 – 52 HRC | 53 HRC | 57 – 60 HRC |
| Tensile strength, MPa (ksi) | 1450 (200) | 1850 (250) | 2068 (300) | 2490 (350) |
| Yeild Strength | 1380 Mpa | 1800 Mpa | 2010 Mpa | 2363 |
| Elongation | 12% | 10 – 12% | 11% | 7.50% |
| Iron content | balance | balance | balance | balance |
| Nickel content | 17.0–19.0% | 17.0–19.0% | 18.0–19.0% | 18.0–19.0% |
| Cobalt content | 8.0–9.0% | 7.0–8.5% | 8.5–9.5% | 11.5–12.5% |
| Molybdenum content | 3.0–3.5% | 4.6–5.2% | 4.6–5.2% | 4.6–5.2% |
| Titanium content | 0.15–0.25% | 0.3–0.5% | 0.5–0.8% | 1.3–1.6% |
| Aluminium content | 0.05–0.15% | 0.05–0.15% | 0.05–0.15% | 0.05–0.15% |
Excellent properties of maraging steel
- High yield strength
- High tensile strength
- High toughness
- High ductility
- high impact strength
- high fatigue strength
- machinability
- High crack growth resistance
- Solderability
- Heat treatment characteristics
- Low thermal expansion coefficient
Maraging steels are used in aircraft and other industrial applications where high strength-to-weight ratio materials are required. The table below lists some of the most common applications for maraging steels：
Category 1 – Aerospace and aircraft parts
- Anchor rails
- Arresting hooks
- Gimbal ring pivots
- Rocket motor cases
- Load cells
- Shock absorbers for lunar rover
- Universal flexures
Category 2 – Production tools
- Aluminium and zinc dies
- Casting and forging dies
- Carbide die holders
- Extrusion press rams, dies, and containers
- Gears for machine tools
- Index plates
- Pistons
- Springs
- Stub shafts
- Cold reducing mandrels
Category 3 – Military
- Cannon recoil springs
- Lightweight portable military bridges
- Rocket motor cases
Category 4 – Other industries
- Auto-racing car parts (rods, shafts, gears)
- Uranium enrichment plants parts (rotors, shafts)
- Cable sockets
- Hydraulic hoses
- Pump impellers and casings
- Tensile test equipment
- Rotors for ultracentrifuges
In addition to this, maraging steel alloy powders have recently been increasingly used to 3D print parts