Руководство по мартенситно-стареющей стали

Джон
Март 16, 2025

Maraging steel is the secret hero behind rockets, medical tools, and ultra-strong industrial parts. Unlike regular steel, it gains superhuman strength through a special heat treatment, not carbon.

At SteelPro Group, we’ve helped engineers use this material to solve tough challenges for over 20 years. In this article, you’ll learn what makes maraging steel unique, where it shines, and how to work with it effectively

What Is Maraging Steel?

Maraging steel is a super-strong alloy with nearly zero carbon content (<0.03%). It’s made from an iron-nickel base, combined with cobalt, molybdenum, and titanium. Unlike regular steel, which uses carbon to gain hardness, maraging steel gets strength through heat treatment. During this process, tiny particles like Ni₃Mo form, locking the structure together. This is known as “aging.”

In its raw form, maraging steel is soft enough to cut or shape easily, with a hardness of RC30-35. But after aging, it transforms into a material that’s incredibly strong and shock-resistant. This makes it perfect for:

Aerospace parts needing lightweight strength
Precision molds requiring exact shapes
Critical components where failure isn’t an option

Why the Name?

“Mar” = Martensite: The initial tough-but-workable structure.
“Aging” = The timed heat treatment that locks in strength.

Maraging Steel Key Characteristics

Strength-to-Weight Champion: Outperforms titanium alloys in load-bearing applications.
Термическая стабильность: Maintains precise dimensions during aging.
Устойчивость к трещинам: Withstands impact forces better than most high-strength alloys, even at sub-zero temperatures.
Corrosion Defense: Inherent resistance to hydrogen embrittlement and stress corrosion cracking.
Machining-Friendly Soft Stage: Easily shaped/cut in the annealed state (pre-aging).
Weldable Without Preheating: Allows on-site repairs – a rare trait among ultra-strong metals.

Maraging Steel Grades at a Glance

Оценка	AMS Standard	Предел прочности	Cobalt Content	Titanium Content	Типичные применения
C200	AMS 6511	1380 МПа	8-9%	0.15-0.25%	Injection molds, structural brackets
C250	AMS 6512	1,720 MPa	7-8.5%	0.3-0.5%	Aerospace gears, hydraulic systems
C300	AMS 6514	2,070 MPa	8.5-9.5%	0.5-0.8%	Rocket motor casings, extrusion dies
C350	AMS 6515*	2,410 MPa	11.5-12.5%	1.3-1.6%	Nuclear centrifuges, military components
*C350 requires export licenses under nuclear non-proliferation agreements.

All grades undergo strict vacuum melting (VIM/VAR) to minimize impurities. At SteelPro Group, we help clients select the optimal grade based on cost, fabrication needs, and end-user demands.

Maraging Steel Chemical Composition

Оценки	C200	C250	C300	C350
Никель (Ni)	17.0–19.0	17.0–19.0	18.0–19.0	18.0–19.0
Кобальт (Co)	8.0–9.0	7.0–8.5	8.5–9.5	11.5–12.5
Молибден (Mo)	3.0–3.5	4.6–5.2	4.6–5.2	4.6–5.2
Титан (Ti)	0.15–0.25	0.3–0.5	0.5–0.8	1.3–1.6
Алюминий (Al)	0.05–0.15	0.05–0.15	0.05–0.15	0.05–0.15
Углерод (С)	≤0,03	≤0,03	≤0,03	≤0,03
Кремний (Si)	≤0,10	≤0,10	≤0,10	≤0,10
Марганец (Mn)	≤0,10	≤0,10	≤0,10	≤0,10
Железо (Fe)	Баланс	Баланс	Баланс	Баланс

Maraging Steel Mechanical Properties

Свойство	C200	C250	C300	C350
Предел прочности	1,379 MPa (200 ksi)	1,724 MPa (250 ksi)	2,068 MPa (300 ksi)	2,413 MPa (350 ksi)
Yield Strength (0.2%)	1,724 MPa (250 ksi)	1,930 MPa (280 ksi)	2,275 MPa (330 ksi)	2,620 MPa (380 ksi)
Удлинение (%)	11–15%	10–12%	8–10%	6–8%
Уменьшение площади (%)	50–60%	45–55%	40–50%	25–35%
Hardness (Aged, HRC)	30–35 HRC	50 HRC	54 HRC	58 ЧРС
Fracture Toughness (KIC)	175 MPa·m¹⁄² (160 ksi√in)	–	–	–

Maraging Steel Physical Properties

Свойство	Метрические единицы	Имперские единицы
Плотность	8.1 g/cm³	0.292 lb/in³
Температура плавления	1,413°C	2,575°F
Теплопроводность	25.5 W/m·K	17.7 BTU·in/hr·ft²·°F
Коэффициент теплового расширения	11.3×10⁻⁶ K⁻¹ (20–100°C)	6.3×10⁻⁶ in/in·°F (68–212°F)
Удельная теплоемкость	452 J/kg·K	0.108 BTU/lb·°F
Модуль Юнга	210 ГПа	30×10⁶ psi
Модуль сдвига	77 ГПа	11.2×10⁶ psi

Мартенситная сталь Приложения

1. Aerospace & Aviation

Structural components: Rocket motor casings, lightweight airframe parts, landing gear.
Engine systems: High-stress turbine shafts, gears, and fasteners.
Satellite hardware: Precision parts requiring high strength-to-weight ratios.

2. Tooling & Dies

Injection molds: Enhanced wear resistance for high-volume production.
Extrusion dies: Superior thermal fatigue resistance for metal forming.
Forging tools: Retains hardness under extreme cyclic loads.

3. Defense & Military

Weapon systems: Firing pins, armored vehicle components.
Ballistic applications: Lightweight armor plating with high impact resistance.

4. Energy & Industrial

Nuclear reactors: Centrifuge rotors for uranium enrichment.
Oil & gas: Downhole tools (drilling mandrels, valves) resistant to H₂S corrosion.

5. Medical & Precision Engineering

Surgical instruments: Biocompatible, non-magnetic properties for MRI compatibility.
High-performance springs: Retains elasticity under repeated stress.

6. Sports & Consumer Goods

High-end bicycles: Frames (e.g., Reynolds 953) for durability and weight savings.
Golf clubs: Club heads optimized for strength and impact resistance.

How Is Maraging Steel Made?

Maraging steel is produced through three key steps:

Alloy Melting:

High-purity iron, nickel, cobalt, and other metals are melted in a vacuum to remove impurities and ensure uniformity.

Термическая обработка:

Отжиг раствора: Heated to dissolve elements, then cooled to form a soft, workable martensite structure.

Старение: Heated at lower temperatures to create tiny, strength-boosting particles (like Ni₃Ti) within the steel.

Shaping & Finishing:

Easily molded (rolled, forged, or machined) while soft. After aging, optional surface treatments (e.g., nitriding) enhance wear resistance.

SteelPro Group Maraging steel is mill-processed to your exact specs, minimizing post-treatment delays. Our team can optimize your workflow from melt to final part.

Maraging Steel Heat Treatment

Maraging steel achieves its exceptional properties through a controlled heat treatment process. Its ultra-low carbon content (<0.03%) allows for flexible processing without brittleness. Below are the key steps:

Solution Annealing: Preparing the Foundation

Process Parameters:

Температура: 820°C (1,510°F)
Soaking Time: 15 minutes for thin sections; 1 hour per 25 mm (1 inch) for thicker parts.
Охлаждение: Air-cooled or oil-quenched to form soft, low-carbon martensite (RC 30–35).

Result:

The steel becomes ductile and workable, with a high dislocation density. This process also removes residual stresses from prior manufacturing steps, ensuring better performance in subsequent stages.

Aging (Precipitation Hardening): Unleashing Strength

Процесс:

Heating to 480–500°C (900–930°F) causes compounds like Ni₃Mo and Ni₃Ti to form. These particles block dislocation movement, strengthening the steel without losing toughness.
The standard aging duration is 3 hours, though it can be extended to 6 hours for complex geometries.
If the temperature exceeds 500°C, coarse phases like Fe₂Mo may form, reducing both strength and ductility. Strict temperature control is crucial to avoid these negative effects.

Result:

The aging process increases the strength of the steel, achieving up to 58 ЧРС for C350 grade. The resulting microstructure significantly boosts the material’s strength without compromising its toughness, making it ideal for demanding applications.

Post-Treatment Enhancements

Азотирование:

Процесс: Nitrogen is diffused into the surface at 500–550°C (930–1,020°F).
Исход: The surface hardness increases to over 60 HRC, making it ideal for wear-resistant parts like gears.

Снятие стресса:

Процесс: Anneal at 815–830°C (1,500–1,525°F) for 1 hour per inch of thickness.
Исход: Stress relieving helps to restore the material’s properties after welding or repairs. It is used for repaired or welded tools (e.g., injection molds).

Maraging Steel Machining and Process

Cold and Hot Working

In its annealed state (RC 30–35), maraging steel can be cold-worked with impressive flexibility. Cold rolling can achieve up to 90% deformation without cracking, making it suitable for thin sheets or precision wire.

For complex shapes, hot working at 1,000–1,100°C (1,832–2,012°F) followed by rapid cooling maintains ductility. After forming, aging treatments restore full strength.

This process is ideal for aerospace fasteners and structural components.

Welding and Joining

Maraging steel’s low carbon content eliminates the need for preheating, simplifying the welding process. TIG (GTAW) и лазерная сварка are preferred methods, as they prevent carbon contamination.

After welding, it’s crucial to re-age the heat-affected zone (HAZ) at 480–500°C for 3 hours. This step removes soft zones and ensures uniform strength, which is critical for pressure vessels and defense hardware.

Key Parameters:

Shielding gas: Argon or helium to prevent oxidation.
Filler material: Matching composition (e.g., 18Ni maraging wire).

Additive Manufacturing (LPBF)

Laser Powder Bed Fusion (LPBF) is transforming the use of maraging steel in lightweight, high-strength components. In this process, fine alloy powder is melted layer by layer using a high-power laser.

Optimized Workflow:

Printing: Laser power of 200–400 W, scan speed of 800–1,200 mm/s.
Снятие стресса: 600°C for 2 hours to reduce residual stresses.
Старение: Standard 480°C treatment boosts strength by 30–40%.

Post-processing steps, such as Hot Isostatic Pressing (HIP), can further improve density and fatigue resistance. This method is especially valuable for parts like satellite brackets and custom medical implants, where complex geometries are essential.

Severe Plastic Deformation (SPD)

For applications requiring extreme strength, SPD techniques like High-Pressure Torsion (HPT) или Equal-Channel Angular Pressing (ECAP) are used to refine the steel’s microstructure. These processes create ultrafine grains (<100 nm) and dislocation networks, pushing yield strength beyond 3.0 GPa.

While expensive, SPD is crucial for applications like armor plating and high-cycle fatigue components in defense systems.

Maraging Steel Pros and Cons

Maraging Steel Advantages

Strength-Toughness Balance: Exceeds tool steels (e.g., H13) and titanium alloys, with tensile strength up to 3.5 GPa and fracture toughness over 175 MPa·m¹⁄².
Ease of Fabrication: Cold workable (up to 90% deformation), weldable without preheating, and polishable to a mirror finish.
Environmental Resistance: High resistance to hydrogen embrittlement and stress corrosion cracking.

Maraging Steel Limitations

High Cost: Driven by nickel and cobalt content, limiting use in budget-sensitive projects.
Temperature Limits: Strength declines sharply above 400°C due to austenite reversion.
Post-Aging Machining Complexity: Requires carbide tools for hardened states (RC 55+), reducing efficiency.

Optimize Your Project with Trusted Maraging Steel Expertise

With over 20 years of experience solving complex engineering challenges, we ensure your maraging steel components meet and exceed performance standards. At Группа компаний SteelPro, we connect material science with real-world applications. Our certified team delivers Grade-Specific Solutions, from cost-effective C200 tooling to export-compliant C350 nuclear components.