Datasheet published 18 March 2024. Last reviewed 21 August 2026 by the metallurgical team at Jiangyin Jiangnan Metal Co., Ltd.
§1 What Maraging 250 is
Maraging 250 belongs to the 18% nickel maraging steel family. The name combines martensitic and aging, which describes how the alloy is hardened.
The composition is about 18% nickel, 7.5 to 8.5% cobalt and 4.6 to 5.2% molybdenum, with small titanium and aluminium additions and carbon held below 0.03%. Cooling from the solution annealing temperature gives a soft, carbide-free lath martensite at 28 to 35 HRC. A low-temperature age at about 480 °C then precipitates Ni3Mo and Ni3Ti particles a few nanometres across, and yield strength roughly doubles to a minimum of 1,725 MPa. The figure 250 in the grade name is that yield strength expressed in ksi.
For anyone specifying a forging, this hardening route has three practical effects.
- No quench, so little distortion. Both heat treatment stages are air cooled. Large rings and long shafts hold their shape, which is why the grade is chosen for parts that would warp in oil or water.
- Machine soft, harden last. Cutting, drilling and forming are done in the annealed condition. The final age adds only a small, repeatable shrinkage of 0.04 to 0.08%.
- Toughness at very high strength. With no carbides to nucleate cleavage, fracture toughness stays in the region of 90 to 120 MPa·m½, at a strength level where quenched and tempered steels are far more notch sensitive.
Note on our catalogue
Maraging 250 is an iron-based steel, not a nickel-base superalloy. It sits in our Nickel Alloy section because of its 18% nickel content and because buyers search for it alongside Inconel, Incoloy and Waspaloy. Metallurgically it belongs with ultra-high-strength steels such as 300M and AerMet 100.
§2 Specifications and equivalents
AMS 6512 is the controlling specification for Maraging 250 bar and forging stock, and it is what most aerospace purchase orders reference. There is no direct EN, JIS or GB equivalent grade, so quote the AMS or ASTM designation on the order.
| System | Designation | Scope |
|---|---|---|
| UNS | K92890 | Unified numbering system |
| SAE / AMS | AMS 6512 | Bars, forgings, tubing and rings, consumable-electrode vacuum melted, annealed |
| ASTM | A538 Grade B | Pressure vessel plate, sheet and strip, 18Ni maraging |
| ASTM | A579 Grade 72 | Superstrength alloy steel forgings |
| Werkstoff / DIN | 1.6359 (X2NiCoMo18-8-5) | German material number, aviation handbook |
| US military | MIL-S-46850 Type 250 | Maraging steel, 18% nickel |
| British | BS S162, DTD 5212 | Bars, billets and forgings |
| Rolls-Royce | MSRR 6551 | Material specification |
| Trade names | Vascomax C250, Udimar 250, NiMark 250, Marvac 250 | Proprietary equivalents |
Trade names are the property of their respective owners and are listed for cross-reference only.
§3 Chemical composition
Composition limits below follow AMS 6512. Maraging 250 is double vacuum melted, by vacuum induction melting followed by vacuum arc remelting (VIM + VAR), to hold sulphur, phosphorus and non-metallic inclusions low. Inclusion cleanliness controls fatigue life at these strength levels. A VIM + ESR + VAR triple-melt route is available where the customer specification calls for it.
| Element | Minimum | Maximum | Role |
|---|---|---|---|
| Nickel (Ni) | 17.00 | 19.00 | Forms the tough carbide-free martensite matrix |
| Cobalt (Co) | 7.00 | 8.50 | Lowers Mo solubility, drives precipitation |
| Molybdenum (Mo) | 4.60 | 5.20 | Forms Ni3Mo strengthening precipitates |
| Titanium (Ti) | 0.30 | 0.50 | Forms Ni3Ti, principal hardener |
| Aluminium (Al) | 0.05 | 0.15 | Deoxidiser, assists aging response |
| Carbon (C) | – | 0.03 | Kept low, carbides would reduce toughness |
| Silicon (Si) | – | 0.10 | Residual |
| Manganese (Mn) | – | 0.10 | Residual |
| Phosphorus (P) | – | 0.010 | Impurity, grain-boundary embrittlement |
| Sulphur (S) | – | 0.010 | Impurity, inclusion control |
| Iron (Fe) | Balance | Matrix | |
Melt analysis and product analysis are both reported on the mill test certificate for every heat.
§4 Mechanical and physical properties
Maraging 250 is supplied in one of two conditions, and they behave very differently. Ordering the wrong one is the most common mistake on maraging steel enquiries, so state the delivery condition on the purchase order.
| Property | Solution annealed | Aged, specified minimum | Aged, typical |
|---|---|---|---|
| Tensile strength | about 1,000 MPa (145 ksi) | 1,790 MPa (260 ksi) | 1,830 to 1,930 MPa (265 to 280 ksi) |
| Yield strength, 0.2% offset | about 760 MPa (110 ksi) | 1,725 MPa (250 ksi) | 1,760 to 1,860 MPa (255 to 270 ksi) |
| Elongation, 4D | 17 to 20% | 6% | 10 to 12% |
| Reduction of area | 70 to 75% | 35% | 45 to 58% |
| Hardness | 28 to 35 HRC | 48 HRC | 48 to 52 HRC |
| Charpy V-notch impact | – | – | 24 to 34 J (18 to 25 ft·lb) |
| Fracture toughness KIC | – | – | 90 to 120 MPa·m½ |
Acceptance limits are set by the controlling specification and the purchase order. Values above are for guidance. Certified results for the actual heat appear on the MTC.
| Property | Value |
|---|---|
| Density | 8.0 g/cm³ (0.289 lb/in³) |
| Modulus of elasticity | about 186 GPa (27 × 106 psi) |
| Mean coefficient of thermal expansion, 20 to 300 °C | about 10.1 × 10−6 /°C |
| Thermal conductivity | about 20 W/m·K |
| Melting range | about 1,413 °C (2,575 °F) |
| Magnetic response | Ferromagnetic |
| Useful service temperature | up to about 400 to 450 °C |
| Low-temperature behaviour | good notch toughness to −50 °C and below |
Important
Maraging 250 is not a high-temperature alloy. It over-ages and loses strength above about 450 °C, so it should not be substituted for a nickel-base superalloy in combustors, transition ducts, flame holders or afterburner liners. For those parts use Inconel 625, Hastelloy X, Haynes 230 or Waspaloy.
§5 Heat treatment
The heat treatment is two air-cooled stages, with no quench and no protective atmosphere needed, since the alloy is essentially carbon free. Aging temperature control is the critical variable, and a 5 °C deviation shows up in the tensile result.
- Solution anneal815 to 830 °C, 1 h per 25 mm, air cool
- Soft martensite28 to 35 HRC, fully machinable
- Machine and formleave allowance for shrinkage
- Age harden480 ±5 °C, 3 to 6 h, air cool
- Peak strength48 to 52 HRC, 1,725 MPa YS min
- Verifytensile, hardness, UT, dimensional
Practical notes
- Shrinkage on aging is about 0.04 to 0.08%, or 0.4 to 0.8 mm per metre, and it is repeatable enough to design around.
- Do not over-age. Holding much above 500 °C starts to revert martensite to austenite and drops strength.
- Re-solution annealing is permitted if a part needs reworking. The aging response is not lost.
- Nitriding at 455 to 480 °C can replace or run alongside the aging cycle, giving a wear-resistant case above 60 HRC over a 48 to 52 HRC core.
- Avoid slow cooling from above about 1,000 °C after forging, which can embrittle 18Ni maraging grades along prior-austenite boundaries.
§6 Forged product forms and sizes
Jiangyin Jiangnan Metal Co., Ltd. produces Maraging 250 as open-die forgings and seamless rolled rings, worked from vacuum-melted billet. Forging starts at 1,150 to 1,250 °C and finishes above about 900 °C, followed by air cooling, with the reduction ratio set to break down the cast structure and refine grain through the section.
| Form | Range | Common uses |
|---|---|---|
| Seamless rolled rings | OD 200 to 3,500 mm, wall 40 to 500 mm, height 30 to 600 mm | Bearing races, retaining rings, drive rings |
| Forged rings and flanges | OD up to 2,500 mm | Housings, mounting flanges, adapters |
| Discs and blanks | Ø 100 to 2,000 mm, thickness 30 to 600 mm | Gear blanks, coupling discs, tooling blanks |
| Round bar and shafts | Ø 60 to 800 mm, length up to 6,000 mm | Drive shafts, spindles, actuator rods |
| Stepped and eccentric shafts | to drawing | Transmission and press components |
| Hollow bar, sleeves, bushings | bore from 80 mm | Cylinders, liners, bushings |
| Forged blocks and plates | thickness up to 500 mm | Die blocks, mould bases, fixtures |
| Single-piece weight | 20 to 8,000 kg | – |
Delivery condition
- Solution annealed, rough machined. The usual choice when the customer does their own finish machining and aging.
- Solution annealed, black forged with machining allowance. The lowest-cost option.
- Aged and finish machined to drawing, with dimensional report.
- Aged and nitrided where a wear-resistant surface is required.
§7 Where Maraging 250 is used
Maraging 250 is specified when a part needs extreme strength, good toughness and tight dimensional stability, and when the cost of cobalt, nickel and vacuum melting is justified by the consequences of failure.
Aerospace and defence structures
Landing gear components, actuator rods and pistons, helicopter rotor shafts and flexbeams, engine drive shafts, wing and fuselage fittings, ejector-seat parts and rocket motor cases. High strength-to-weight ratio combined with low distortion in heat treatment is the reason it is used here.
Tooling and die making
Aluminium and zinc die-casting dies and cores, aluminium extrusion dies, cold-heading and cold-forming punches and dies, plastic injection mould inserts, and hot-forging tooling for non-ferrous metals. Since the die is machined soft and aged at only 480 °C, complex cavities come out of heat treatment close to the shape they went in.
Motorsport and high-performance drivetrain
Transmission gears, driveshafts, constant-velocity joints, crankshafts, differential components and clutch parts, where fatigue strength and impact resistance justify the material cost.
Precision and industrial equipment
Machine tool spindles, load cells and flexures that depend on dimensional stability, high-load fasteners and studs, hydraulic and isostatic press components, torque tools, and springs and diaphragms working at high stress.
Where not to use it
Maraging 250 contains almost no chromium, so it rusts like a low-alloy steel and always needs a protective finish. It is not suitable for NACE MR0175 sour service, seawater exposure without coating, chemical process wetted parts, or service above about 450 °C. For corrosive duty at high strength, consider PH13-8Mo, 17-4PH or Inconel 725.
§8 Maraging 250 against 300, 350 and other high-strength steels
Within the 18Ni maraging family, strength rises and toughness falls as cobalt and titanium go up. Maraging 250 sits where most large forgings land: enough strength for the job, with the toughness to survive dynamic loading.
Nominal minimum yield strength in the aged condition. Toughness moves in the opposite direction.
| Grade | Specification | Co | Ti | Yield, aged | Hardness | Best for |
|---|---|---|---|---|---|---|
| Maraging 200 | ASTM A538 Gr A | 8.5 | 0.2 | 1,400 MPa | about 44 HRC | Formability, weld-heavy assemblies |
| Maraging 250 | AMS 6512, A538 Gr B | 7.5 to 8.5 | 0.3 to 0.5 | 1,725 MPa | 48 to 52 HRC | Best strength-to-toughness balance, large forgings |
| Maraging 300 | AMS 6514, A538 Gr C | 8.5 to 9.5 | 0.55 to 0.8 | about 2,000 MPa | 52 to 56 HRC | Higher strength where toughness margin allows |
| Maraging 350 | AMS 6515 | 11.5 to 12.5 | 1.3 to 1.6 | about 2,400 MPa | 56 to 60 HRC | Maximum strength, small sections only |
Against quenched and tempered ultra-high-strength steels
AISI 4340 and 300M reach comparable tensile strength at much lower material cost, but they need an oil quench and a carefully controlled temper, they distort, and their notch toughness at peak strength is lower. AerMet 100 offers strength and toughness in the same class as Maraging 250 and better than Maraging 300, at a similar or higher price, but it also requires a quench. In short, choose Maraging 250 when distortion control, weldability or toughness at 250 ksi decide the design, and choose 4340 or 300M when cost decides it and the geometry tolerates quenching.
§9 Machining, welding and finishing
Machining
Machine in the solution annealed condition at 28 to 35 HRC, where the alloy cuts at roughly the rate of quenched and tempered 4340. It work-hardens, so use sharp tools, positive rake, rigid setups, heavy feeds and light depth of cut, and do not let the tool dwell. Aged material at 48 to 52 HRC can be ground and hard-turned with CBN, but bulk metal removal after aging is slow and expensive, so plan the sequence to avoid it.
Welding
Carbon below 0.03% means the heat-affected zone does not form brittle martensite, so Maraging 250 welds more easily than most steels at the same strength. Weld in the annealed condition by GTAW, plasma or electron beam with matching filler, without preheat, keeping heat input low. Age the assembly at 480 °C afterwards to bring weld and parent metal to full strength together.
Surface protection
Corrosion resistance is only that of a low-alloy steel, so forgings are shipped oiled and should be plated, painted, phosphated, black-oxided or nitrided for service. Where electroplating is used, follow it with a hydrogen embrittlement relief bake, since the alloy is sensitive to hydrogen at this strength level.
§10 Testing, certification and traceability
Every Maraging 250 forging leaving Jiangyin Jiangnan Metal Co., Ltd. is released against a documented test package tied to the heat and lot number.
- Chemistry. Melt analysis and product analysis, both reported.
- Mechanical testing. Tensile, yield, elongation, reduction of area, hardness survey, and Charpy V-notch impact on request, from test blanks heat treated with the production parts.
- Ultrasonic examination. EN 10228-3, ASTM A388 or SEP 1921, to the acceptance class stated on the order.
- Surface NDT. Magnetic particle to ASTM E1444 or dye penetrant to ASTM E1417.
- Grain size and cleanliness. ASTM E112 and ASTM E45 where specified.
- Heat treatment records. Furnace charts for both the solution anneal and the age.
- Dimensional report for finish-machined parts.
- Certification. EN 10204 3.1 as standard, 3.2 witnessed by TUV, SGS, BV or Lloyd's on request.
Trade compliance
Maraging steels are treated as dual-use controlled items in a number of jurisdictions. Jiangyin Jiangnan Metal Co., Ltd. supplies Maraging 250 for civil industrial and commercial applications only, and requires end-user and end-use documentation before shipment. Buyers remain responsible for import licensing and for compliance with the rules that apply in their own country.
§11 How to order
Send a drawing or the finished dimensions and Jiangyin Jiangnan Metal Co., Ltd. will return a quotation, forging plan and test scope, normally within 24 hours. To get a firm price first time, include:
- Drawing or dimensions, with machining allowance if the part is to be supplied rough machined.
- Quantity, and whether this is a prototype, a trial order or a series.
- Controlling specification: AMS 6512, ASTM A538 Grade B, MIL-S-46850 or a customer specification.
- Delivery condition: solution annealed or aged, black or machined.
- Test and certification requirements, including UT acceptance class.
- Destination port and required delivery date.
| Item | Detail |
|---|---|
| Minimum order | 1 piece, trial and prototype orders accepted |
| Lead time | 20 to 45 days, depending on size, heat treatment and machining |
| Quotation turnaround | within 24 hours of receiving a drawing |
| Incoterms | EXW, FOB Shanghai or Ningbo, CIF, DDP |
| Payment | T/T or irrevocable L/C at sight |
| Packing | Rust-preventive oil, VCI film, fumigation-free plywood cases |
§12 About the manufacturer
Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China, in the Yangtze River delta forging cluster, about two hours from the ports of Shanghai and Ningbo.
The works produces open-die forgings and seamless rolled rings in carbon steel, alloy steel, tool steel, stainless steel, nickel alloys and maraging steels, covering rings, discs, shafts, bars, flanges, sleeves, bushings, tube sheets and blocks, all made to customer drawing. Maraging 250 is supplied alongside the rest of the 18Ni maraging family and the precipitation-hardening stainless grades, so one enquiry can be quoted across several candidate materials.
- Made to drawing. No catalogue-only limitation, and one-off and small-batch work is accepted.
- In-house heat treatment with recorded furnace charts for both anneal and age.
- Full documentation. EN 10204 3.1 as standard, 3.2 third-party witnessed on request.
- Export experience across Europe, North America, the Middle East and Asia.
Contact the sales engineering team or email sales@steelforgepieces.com with your drawing.
§13 Frequently asked questions
What is Maraging 250 steel?
Maraging 250 is an ultra-high-strength steel containing about 18% nickel, 7.5 to 8.5% cobalt and 4.6 to 5.2% molybdenum, with almost no carbon. It is also known as 18Ni(250), UNS K92890, AMS 6512 and W.Nr. 1.6359. Strength comes from nanoscale Ni3Mo and Ni3Ti precipitates formed during a low-temperature age at about 480 °C, not from carbon and quenching. In the aged condition it reaches a minimum yield strength of 1,725 MPa (250 ksi).
What is the difference between Maraging 250 and Maraging 300?
Maraging 300 carries higher cobalt and titanium and reaches about 2,000 MPa yield strength against 1,725 MPa for Maraging 250, but it is less tough. Maraging 250 keeps higher fracture toughness and better ductility, so it is usually the better choice for large forged rings and shafts carrying dynamic or impact loads. Maraging 300 is chosen where peak strength or hardness matters most.
What is the maximum service temperature of Maraging 250?
Maraging 250 holds its strength up to about 400 to 450 °C. Above that the aged structure over-ages and strength falls away. It is not a high-temperature alloy and should not be substituted for nickel superalloys such as Inconel 718, Waspaloy or Hastelloy X in combustors, transition ducts or other hot-section gas turbine parts. Notch toughness stays good down to −50 °C and below.
Does Maraging 250 need to be quenched?
No. Both stages are air cooled. Solution annealing at 815 to 830 °C is followed by air cooling, and aging at 480 °C is also followed by air cooling. With no water or oil quench, distortion and residual stress are much lower than in quenched and tempered steels of the same strength, which is why the grade suits large, precise forged components and die-casting dies.
Is Maraging 250 corrosion resistant?
No. Maraging 250 contains almost no chromium and corrodes much like a low-alloy steel, so it needs oil, paint, plating, nitriding or another protective finish in service. Its resistance to stress corrosion cracking is better than that of quenched and tempered steels at the same strength level, but it is not a stainless steel and is not suitable for NACE MR0175 sour service.
Can Maraging 250 be welded?
Yes. Carbon content below 0.03% means the heat-affected zone does not form brittle martensite, so Maraging 250 welds more easily than most steels of the same strength. It is normally welded in the solution annealed condition by GTAW, plasma or electron beam with matching filler and without preheat, and the assembly is then aged at 480 °C to bring weld and parent metal to full strength.
Which product forms of Maraging 250 does Jiangyin Jiangnan Metal supply?
Jiangyin Jiangnan Metal Co., Ltd. supplies Maraging 250 as open-die forgings made to customer drawing: seamless rolled rings, forged rings and flanges, discs and blanks, round bars and shafts, stepped and eccentric shafts, hollow bars, sleeves, bushings, tube sheets and forged blocks. Material can be delivered solution annealed for the customer to machine and age, or fully aged and machined to finished dimensions.
What certification is supplied with Maraging 250 forgings?
Every order ships with a mill test certificate to EN 10204 3.1, and 3.2 certification witnessed by a third party such as TUV, SGS, BV or Lloyd's is available on request. Certificates cover melt and product analysis, tensile and hardness results, heat treatment records with furnace charts, ultrasonic examination to EN 10228-3, ASTM A388 or SEP 1921, and full heat and lot traceability.
How do I order Maraging 250 forgings from China?
Send a drawing, or the finished dimensions, quantity, controlling specification and delivery condition, to sales@steelforgepieces.com or call +86-189-2135-9659. Jiangyin Jiangnan Metal Co., Ltd. returns a quotation with forging plan, test scope and lead time, normally within 24 hours. Typical lead time is 20 to 45 days depending on size and heat treatment, and trial quantities of a single piece are accepted.
§14 References
Composition, property and heat treatment data on this page are taken from the published specifications and reference works below, and cross-checked against production test results at Jiangyin Jiangnan Metal Co., Ltd. Where a range is given, the controlling specification and the purchase order take precedence.
- SAE AMS 6512. Steel Bars, Forgings, Tubing and Rings, 18Ni 7.8Co 4.9Mo 0.40Ti 0.10Al, consumable-electrode vacuum melted, annealed.
- ASTM A538/A538M. Pressure Vessel Plates, Alloy Steel, Precipitation Hardening (Maraging), 18 Percent Nickel, Grade B.
- ASTM A579/A579M. Superstrength Alloy Steel Forgings, Grade 72.
- MIL-S-46850. Steel, Bar, Plate, Sheet, Strip, Forgings and Extrusions, 18 Percent Nickel Alloy, Maraging, Type 250.
- ASM Handbook, Volume 4, Heat Treating. Heat treating of maraging steels.
- ASM Specialty Handbook, Carbon and Alloy Steels. The 18Ni maraging steel family.
- EN 10204, Metallic products, types of inspection documents. EN 10228-3, Non-destructive testing of steel forgings, ultrasonic testing of ferritic or martensitic steel forgings.
This datasheet is provided for guidance. It is not a warranty of properties for a specific application and does not replace the controlling specification. Contact our engineering team to confirm suitability for your design.