Custom Maraging Steel Springs
Coiling Technologies is a certified custom industrial spring manufacturer. We create custom sizes for a variety of springs with applications in heavier industries, such as military or oil & gas. Our springs have proven to be effective and high-quality through years of usage in harsh conditions.
Whatever the demand, Coiling Technologies will meet it with the highest performance parts, made from the best materials, such as Maraging C300 and C350. We produce products for industrial use, so we make sure our springs are reliable and durable.
Maraging Steel Spring Features & Benefits
Maraging steel springs are carbon-free iron-nickel alloys with the addition of cobalt strengthen steel (C-type), molybdenum, titanium, and aluminum. Maraging steels belong to the category of ultra-high-strength materials which have excellent toughness properties. C300 grade has tensile strength properties up to 300 Ksi and C350 is up to 350 Ksi while still retaining excellent ductility.
The main benefit of this material is that it is an easily shaped hard steel containing many other useful properties.
| Technical Specification | Maraging C300 | Maraging C350 |
|---|---|---|
| Nominal Composition |
Ni:18.0 - 19.0 Mo: 4.6 - 5.20 Fe: Balance |
Ni:18.0 - 19.0 Mo: 4.6 - 5.20 |
| Density |
0.289 lb./in3, (8.0 g/cm3) |
0.292 lb./in3, (8.1 g/cm3) |
| Modulus of Elasticity (E) |
27.5 x 106 psi |
29 x 106 psi |
| Modulus of Rigidity (G) |
10.6 x106 psi |
11.2 x 106 psi |
| Coefficient of Expansion |
5.6 µin/in.-°F (70°F to 900°F) |
6.3 µin/in.-°F (70°F to 900°F) |
| Electrical Resistivity |
68.5 µΩ.in, (174 µΩ.cm) |
68.5 µΩ.in, (174 µΩ.cm) |
| Thermal Conductivity |
176Btu-in/ft2hr-°F, (25.3 W/m-K) |
176Btu-in/ft2hr-°F, (25.3 W/m-K) |
| Min Size |
0 |
0 |
| Max Temp |
482oC (900oF) |
482oC (900oF) |
| Uses of Maraging Steel Springs |
It is resistant to crack propagation and used in aircraft or high-performance racing springs |
C350 alloy is heavier and harder than C300 due to higher amounts of Cobalt. Used in high end military applications, such as, recoil springs for heavy guns. |
Maraging C300 & C350 Spring Applications
Maraging steel is commonly used in military defense applications and high-performance gears and shafting. Our springs are used as valve springs in oil pumps, firearms parts, and torsion springs in aerospace equipment. Maraging steel springs are used frequently when there is a need for a high strength-to-weight ratio. Applicable standards for Maraging Steels are MIL-S-46850D,
Applications for these springs include:
- Recoil and torsion for military tanks
- High-Performance Vehicle suspensions
- Oil and petroleum pumps and equipment
- Heavy machinery
Industries Using Maraging C300 & C350 Springs
Coiling technologies springs are used in many industries from military defense to the automotive aftermarket. Nearly any industry with heavy equipment or large applications can benefit greatly from our high strength, temperature resistance springs.
Some other common industries we serve:
- Mining
- Construction
- Recreation equipment
- Agriculture
- Material handling
- Aerospace
- Automotive
Types of Springs Coiling Technologies Offers:
- Custom springs
- Die springs
- Compression springs
- Torsion springs
- Disc springs
- Suspension springs
- Wire forms
- Draw bar springs
- Extension springs
- Wave springs
What Sets Coiling Technologies Apart?
Coiling Technologies works to create custom springs to meet every demand in your industry. From custom small and large coils, to a wide variety of materials and options to choose from, we can help you create the exact springs you are looking for!
Coiling Tech’s experienced team will be happy to help, contact us today.
Maraging C300 and C350 Springs FAQs
What are maraging steel springs and what makes them different from standard alloy steel?
Maraging steels are carbon-free (or near-zero carbon) iron-nickel alloys strengthened with cobalt, molybdenum, titanium, and aluminum through an age hardening mechanism rather than carbon-based martensitic strengthening. This unique hardening mechanism produces ultra-high strength—up to 350 ksi tensile—while retaining excellent toughness and ductility that are difficult to achieve simultaneously in conventional high-carbon spring steels. The near-zero carbon content also eliminates the risk of carbon-related hydrogen embrittlement, making maraging steel appropriate for some hydrogen-exposed environments where high-carbon steels would be disqualified.
What is the difference between Maraging C300 and C350?
Maraging C300 achieves ultimate tensile strength up to approximately 300,000 psi (300 ksi) after aging, while C350 reaches up to approximately 350,000 psi (350 ksi) due to its higher cobalt content—making C350 stronger but also heavier and more expensive than C300. C350 is typically reserved for the highest-strength applications where C300's strength level is insufficient, such as recoil springs for heavy artillery and specialty aerospace components. C300 covers a broad range of high-performance aerospace, racing, and defense applications where ultra-high strength at relatively low mass is required but the extreme upper strength limit of C350 is not necessary. Both grades conform to MIL-S-46850D and related aerospace standards.
What applications most commonly use maraging steel springs?
Maraging steel springs are used in: aerospace structures and aircraft components (flap actuator springs, landing gear springs, flight control components where ultra-high strength-to-weight ratio is the primary driver), high-performance motorsport racing suspension springs, valve springs in high-performance engine oil pump applications, firearm and weapons system components (recoil springs for heavy artillery and automatic weapons), torsion springs in aerospace mechanisms and instrumentation, and specialized industrial applications demanding the highest strength-to-weight ratio achievable in a spring steel at moderate service temperatures.
What is the maximum operating temperature for maraging steel springs?
Maraging C300 and C350 springs are rated for continuous service up to approximately 900°F (482°C), providing a notably higher temperature ceiling than standard high-carbon spring steels (approximately 250°F for music wire, approximately 475°F for chrome silicon) while retaining their ultra-high-strength properties. Above approximately 900°F, over-aging begins to reduce strength significantly, and nickel superalloys become the appropriate material choice.
Why are maraging steel springs resistant to crack propagation?
Maraging steels achieve their strength through age hardening of a near-carbon-free martensitic structure rather than through carbon-based quench hardening. This low-carbon martensite is inherently tougher than high-carbon martensite at equivalent hardness levels, giving maraging steel springs a high fracture toughness that resists crack initiation and propagation. This combination of high strength and high toughness is particularly important in aerospace and defense applications governed by damage tolerance standards—programs where a spring must remain structurally sound even with minor surface damage or manufacturing flaws.
Which industries use maraging C300 and C350 springs beyond aerospace and defense?
Beyond military and aerospace, maraging steel springs are used in high-performance motorsport (race car suspension springs where minimum spring weight is critical for handling and unsprung mass reduction), precision tooling and press applications, high-performance engine programs in both motorsport and industrial machinery, and any application where the spring mass itself is a performance-limiting factor and the cost premium over standard alloy spring steel is justified by the weight reduction achieved.
