Vascomax C250 at a glance
- Grade
- Vascomax® C250, also written VascoMax C-250, Maraging 250, 18Ni(250), Grade 250
- Alloy family
- Iron-nickel-cobalt-molybdenum maraging steel. An ultra-high-strength steel, not a nickel-base superalloy, although it is catalogued under Nickel Alloy on this site
- UNS number
- K92890
- Forging standard
- AMS 6512 (bar, forgings, tubing); ASTM A538 Grade B; MIL-S-46850 Grade 250
- Werkstoff / DIN
- 1.6359 / X2NiCoMo18-8-5
- Nominal chemistry
- 18% Ni, 8% Co, 5% Mo, 0.4% Ti, 0.1% Al, balance Fe, carbon 0.03% max
- Melting route
- VIM + VAR for aerospace work; VIM + ESR or EAF + VOD + ESR for tooling and general industrial work
- Yield strength, aged
- 1,725 MPa (250 ksi) minimum. The “250” in the grade name is the yield strength in ksi
- Hardness, aged
- 48–52 HRC
- Hardness, annealed
- 30–35 HRC, machinable in this condition
- Hardening treatment
- 815 °C solution anneal, air cool → 482 °C age 3–6 h, air cool. No quench, no temper
- Distortion on hardening
- Uniform contraction of roughly 0.04–0.08% (0.4–0.8 mm/m)
- Maximum service temperature
- About 400 °C (750 °F). Not a high-temperature alloy
- Corrosion resistance
- None. Not a stainless steel; requires plating, coating or oil in service
- Weldability
- Excellent. No preheat; re-age after welding
- Delivery condition
- Solution annealed (standard) or solution annealed + aged, to your order
- Certification
- EN 10204 3.1 as standard; 3.2 third-party witnessed on request
- Forged by
- Jiangyin Jiangnan Metal Co., Ltd., Jiangyin, Jiangsu, China
What Vascomax C250 is, and when to specify it
Vascomax C250 is an 18% nickel maraging steel that gets its strength from intermetallic precipitation during a low-temperature age, not from a carbon quench.
Conventional high-strength steels such as 4340, 300M and H13 are hardened by quenching carbon-bearing austenite into martensite and then tempering it back. That route brings quench distortion, residual stress and a real risk of quench cracking in a thick or awkward section. Maraging steels avoid it. Carbon is held down to 0.03% maximum and nickel is raised to 18%, so that on cooling from 815 °C the structure transforms to a body-centred-cubic iron-nickel martensite that is soft and tough at 30–35 HRC. The transformation occurs at any cooling rate, which means a still-air cool through a heavy section works as well as a quench.
Strength develops in the second stage. Holding the soft martensite at 482 °C for three to six hours precipitates fine, coherent Ni₃Mo and Ni₃Ti particles throughout the matrix. Hardness rises to 48–52 HRC and yield strength to 1725 MPa (250 ksi) minimum. Cobalt forms no precipitate of its own. It lowers the solubility of molybdenum in the matrix, which drives the Ni₃Mo reaction and accounts for the 8% cobalt addition.
Specify Vascomax C250 when you need strength above roughly 1,700 MPa and at least one of the following: a part too complex or too thin to survive a quench; a weld that has to develop full strength; a tool that will be repaired by welding several times over its life; or a component where post-hardening distortion cannot be machined out. If none of those apply and 1600 MPa is enough, a quenched and tempered 4340 will do the job for a fraction of the price.
Naming: Vascomax® is a registered trade name. The generic designation for the same material is 18Ni(250) maraging steel, UNS K92890. Order to UNS K92890 and AMS 6512 and the requirement is unambiguous regardless of who melts it.
Chemical composition of Vascomax C250
The limits below are the AMS 6512 composition window for UNS K92890, in weight percent. It is the specification range Jiangyin Jiangnan Metal forges to. Every heat is supplied with a ladle analysis on the mill certificate; product analysis on the finished forging can be added on request.
| Element | Minimum | Maximum | Role in the alloy |
|---|---|---|---|
| Nickel (Ni) | 17.00 | 19.00 | Forms the soft, carbon-free iron-nickel martensite that hardens on ageing |
| Cobalt (Co) | 7.00 | 8.50 | Lowers molybdenum solubility in the matrix, driving Ni₃Mo precipitation |
| Molybdenum (Mo) | 4.60 | 5.20 | Principal hardening element; forms Ni₃Mo on ageing |
| Titanium (Ti) | 0.30 | 0.50 | Forms Ni₃Ti; the main lever separating C250 from C300 and C350 |
| Aluminium (Al) | 0.05 | 0.15 | Deoxidiser; small contribution to age hardening |
| Carbon (C) | — | 0.03 | Deliberately kept out. Carbon forms brittle titanium carbides and consumes Ti |
| Manganese (Mn) | — | 0.10 | Residual limit; kept low to protect toughness |
| Silicon (Si) | — | 0.10 | Residual limit; kept low to protect toughness |
| Phosphorus (P) | — | 0.010 | Grain-boundary embrittler; tightly controlled |
| Sulfur (S) | — | 0.010 | Forms inclusions that cut transverse ductility and toughness |
| Iron (Fe) | balance | balance | Base element, roughly 65–70% of the alloy |
Source: Jiangyin Jiangnan Metal Co., Ltd., Vascomax C250 forging specification, compiled from AMS 6512. Highlighted blue rows are the four elements that define the hardening reaction; the highlighted orange row is the deliberate exclusion that distinguishes maraging steel from every other high-strength steel.
In a conventional steel, carbon is the hardening element. In a maraging steel it behaves as a contaminant: any carbon present ties up titanium as TiC, removing it from the Ni₃Ti reaction, and the carbides act as fracture initiation sites. The 0.03% ceiling is the reason C250 has to be melted under vacuum or under slag rather than in open air.
Mechanical properties of Vascomax C250 forgings
Aged condition: solution annealed and precipitation treated
This is the condition C250 is used in. The minimum column is what we certify on the mill test certificate; the typical column is what our production normally returns on longitudinal test bars from forged sections.
| Property | Minimum, metric | Minimum, imperial | Typical range |
|---|---|---|---|
| Tensile strength | 1,860 MPa | 270 ksi | 1,860–1,930 MPa |
| Yield strength, 0.2% offset | 1,725 MPa | 250 ksi | 1,760–1,830 MPa |
| Elongation on 4D | 12% | 12% | 10–13% |
| Reduction of area | — | — | 45–58% |
| Hardness | 48 HRC | 48 HRC | 48–52 HRC |
| Charpy V-notch impact, 20 °C | — | — | 24–34 J (18–25 ft·lb) |
| Plane-strain fracture toughness KIC | — | — | 80–110 MPa·m½ |
| Modulus of elasticity | — | — | 186 GPa (27.0 × 10⁶ psi) |
Source: Jiangyin Jiangnan Metal Co., Ltd. Minimum values are as published in our Vascomax C250 forging specification. Where your purchase order invokes a different standard or a different test direction, the standard governs. Confirm the required minima at enquiry stage. The mill test certificate issued with each forging governs acceptance.
Solution annealed condition, as normally delivered for machining
Forgings are usually shipped solution annealed so the buyer can machine them soft and age them afterwards. In this condition the steel behaves roughly like a medium-strength alloy steel and cuts easily.
| Property | Metric | Imperial |
|---|---|---|
| Tensile strength | 965–1,035 MPa | 140–150 ksi |
| Yield strength, 0.2% offset | 760–830 MPa | 110–120 ksi |
| Elongation on 4D | 17–19% | 17–19% |
| Reduction of area | 72–80% | 72–80% |
| Hardness | 30–35 HRC | 285–340 HB |
| Modulus of elasticity | 179 GPa | 26.0 × 10⁶ psi |
Typical values for design screening only. They are not specification minimums and vary with section size and forging reduction.
Physical properties of Vascomax C250
| Property | Metric | Imperial |
|---|---|---|
| Density | 8.00 g/cm³ | 0.289 lb/in³ |
| Melting range | 1,413–1,440 °C | 2,575–2,625 °F |
| Modulus of elasticity, aged | 186 GPa | 27.0 × 10⁶ psi |
| Modulus of elasticity, annealed | 179 GPa | 26.0 × 10⁶ psi |
| Poisson's ratio | ≈ 0.31 | ≈ 0.31 |
| Specific heat | ≈ 452 J/kg·K | 0.108 Btu/lb·°F |
| Thermal conductivity, 20 °C | ≈ 20 W/m·K | ≈ 139 Btu·in/ft²·h·°F |
| Mean thermal expansion, 20–500 °C | ≈ 10.1 µm/m·K | 5.6 × 10⁻⁶ in/in·°F |
| Electrical resistivity, annealed | ≈ 0.60 µΩ·m | ≈ 60 µΩ·cm |
| Dimensional change on ageing | −0.04 to −0.08% | −0.0004 to −0.0008 in/in |
| Magnetic response | Ferromagnetic | Ferromagnetic |
Nominal values compiled from published maraging steel literature for guidance in design screening. Approximate values are marked with ≈. Where a physical property is critical to your design, request measured data at enquiry stage.
Ageing shrinks the part by roughly 0.4 to 0.8 millimetres per metre, uniformly and predictably, so the machining sequence has to be planned around it: rough machine before ageing, leave 0.25–0.5 mm of stock per surface, then finish grind or turn. The steel is ferromagnetic, so magnetic particle inspection is available on it, which the austenitic nickel alloys do not allow.
Heat treatment of Vascomax C250
Solution anneal at 815 °C (1500 °F) for one hour per 25 mm of section and air cool; then age at 482 °C (900 °F) for three to six hours and air cool. There is no quench and no temper.
- Solution anneal at 815 °C ± 15 °C, 1 hour per 25 mm, air coolDissolves the intermetallic precipitates and resets the structure to soft iron-nickel martensite at 30–35 HRC. Air cooling is sufficient in any section thickness because the transformation is not diffusion-controlled. A protective atmosphere or vacuum keeps the surface clean; heavy scale means titanium loss from the skin and a soft layer after ageing.
- Rough machineCut the part in the annealed condition, leaving 0.25–0.5 mm per surface for finishing. Machining at this stage is what keeps the grade economic, since the same cut at 50 HRC would have to be ground.
- Age at 482 °C ± 6 °C, 3 to 6 hours, air coolPrecipitates Ni₃Mo and Ni₃Ti. Hardness rises to 48–52 HRC and yield strength to 1,725 MPa minimum. Air atmosphere is acceptable at this temperature; oxidation is light. Time is measured from when the part reaches temperature, not from when it enters the furnace. A heavy forging can take several hours to soak.
- Finish machine or grindRemoves the residual stock and corrects the 0.04–0.08% contraction that occurred during ageing.
Ageing response
Hardness is not very sensitive to time once the reaction is complete, which makes the cycle forgiving in a production furnace. It is sensitive to temperature. The table below shows the practical response; use the heat-treatment planner below to explore intermediate cycles.
| Ageing cycle | Hardness | Yield strength, 0.2% | Result |
|---|---|---|---|
| None (as annealed) | 30–35 HRC | 760–830 MPa | Soft, tough, machinable. Delivery condition |
| 455 °C / 6 h | 45–48 HRC | 1,550–1,650 MPa | Under-aged. Higher ductility, lower strength |
| 482 °C / 3–6 h | 48–52 HRC | 1,725–1,830 MPa | Standard cycle. Full specified properties |
| 510 °C / 3 h | 46–49 HRC | 1,550–1,700 MPa | Onset of over-ageing. Strength falling |
| 540 °C / 3 h | 40–45 HRC | 1,250–1,450 MPa | Reverted austenite. Re-anneal before re-ageing |
Indicative values compiled from published maraging steel data for process planning. Qualify your own cycle on production material before releasing a part to it.
Forging practice for Vascomax C250
Maraging steel forges well but is unforgiving about finishing temperature and about surface contamination. The practice below is what Jiangyin Jiangnan Metal runs on its hammers and hydraulic press for this grade.
| Parameter | Practice | Reason |
|---|---|---|
| Preheat | 760–815 °C, soak, then raise | Avoids thermal shock in heavy ingot sections |
| Forging temperature | Start 1,150–1,260 °C | Full hot workability without incipient melting or grain coarsening |
| Finish temperature | Stop above 815 °C (1,500 °F) | Working below this cracks the piece and produces uneven structure |
| Soaking time | Minimum consistent with through-heating | Long soaks coarsen grain and lose titanium from the surface |
| Reduction ratio | ≥ 3:1 general; ≥ 4:1 for aerospace and critical work | Closes ingot porosity and develops wrought grain flow |
| Cooling after forging | Air cool. Never quench | Water or oil quenching gains nothing and risks cracking |
| Homogenising, heavy sections | 1,150 °C hold before final reduction | Reduces molybdenum and titanium segregation banding |
| Post-forge condition | Solution anneal 815 °C, air cool | Uniform soft martensite ready for machining |
Source: Jiangyin Jiangnan Metal Co., Ltd. open-die forging practice for UNS K92890.
Machining, welding and surface treatment
Machining
Machine in the annealed condition wherever possible. At 30–35 HRC, C250 cuts at roughly half the rate of free-machining B1112 stock and behaves much like 4340 at similar hardness: it is gummy rather than abrasive, so use sharp, positive-rake carbide, rigid setups and generous coolant. Feed steadily; dwelling work-hardens the surface. In the aged condition at 48–52 HRC, grinding, EDM or CBN turning are the practical options.
Welding
Weldability is one of the strongest reasons to choose this grade, and it is unusual among steels at this strength level. C250 can be welded by GTAW, electron beam, laser or plasma, in either the annealed or the fully aged condition, with no preheat, because the carbon content is too low to form a brittle heat-affected zone. Use a matching maraging filler, keep heat input low and the joint clean and dry, and avoid any consumable or contaminant that could introduce carbon or hydrogen. Age or re-age at 482 °C after welding to restore properties across the joint. For full parent-metal properties, re-solution anneal and then age.
Corrosion protection and surface engineering
C250 is not stainless and will rust in humid air. Its general corrosion behaviour is similar to a low-alloy steel, though it resists stress-corrosion cracking somewhat better than a quenched and tempered steel of equal strength. In service it needs a barrier: cadmium or zinc-nickel plating, phosphate and oil, or a paint system. Nitriding suits the grade well. Gas nitriding at around 455 °C runs close to the ageing temperature, so a surface hardness of about 65 HRC can be developed while the core ages, in a single operation.
C200, C250, C300 and C350 compared
The four common 18% nickel maraging grades share the same base and the same heat treatment. They differ almost entirely in titanium and cobalt content, and the grade number is simply the aged yield strength in ksi. Strength rises with titanium; ductility, toughness and weldability fall in step.
| Grade | UNS | Co % | Mo % | Ti % | Aged yield | Aged hardness |
|---|---|---|---|---|---|---|
| 18Ni(200) / C200 | K92810 | 8.0–9.0 | 3.0–3.5 | 0.15–0.25 | 1,380 MPa / 200 ksi | 44–48 HRC |
| 18Ni(250) / C250 | K92890 | 7.0–8.5 | 4.6–5.2 | 0.30–0.50 | 1,725 MPa / 250 ksi | 48–52 HRC |
| 18Ni(300) / C300 | K93120 | 8.5–9.5 | 4.6–5.2 | 0.55–0.80 | 2,000 MPa / 290 ksi | 51–55 HRC |
| 18Ni(350) / C350 | K93160 | 11.5–12.5 | 4.6–5.2 | 1.30–1.60 | 2,400 MPa / 350 ksi | 56–59 HRC |
Nickel is 17.0–19.0% in all four grades and carbon is 0.03% maximum throughout. AMS 6512 covers C250 bar and forgings; AMS 6514 covers C300. Compiled by Jiangyin Jiangnan Metal Co., Ltd. We forge all four grades.
C250 is the practical middle of the family and by far the most widely used. C200 rarely justifies itself, since 4340 covers the same strength more cheaply. C300 buys another 275 MPa of yield but gives up impact energy and fracture toughness, and is less tolerant of section size and of welding. C350 is a specialist grade for the highest strength-to-weight applications and needs careful process control to reach its properties reliably. Unless your design specifically needs the extra strength, C250 gives the best combination of strength, toughness and manufacturability in the family.
Vascomax C250 against 17-4PH and 4340
These three grades are the ones most often traded off against one another on a high-strength component drawing.
| Criterion | Vascomax C250 | 17-4PH, H900 | AISI 4340, quenched & tempered |
|---|---|---|---|
| Yield strength | 1,725 MPa (250 ksi) | 1,170 MPa (170 ksi) | ~1,590 MPa (230 ksi) |
| Hardness | 48–52 HRC | 40–47 HRC | 50–53 HRC |
| Hardening route | Air cool + 482 °C age | Air cool + 480 °C age | Oil quench + temper |
| Distortion on hardening | Very low, uniform ~0.05% contraction | Low | High. Quench distortion and cracking risk |
| Corrosion resistance | None. Needs a coating | Good. Martensitic stainless | None. Needs a coating |
| Welding at full strength | Excellent, no preheat, re-age after | Good, re-age after | Poor at high strength |
| Toughness at strength | High for the strength level | Moderate | Lower at equal strength |
| Machining hardness | 30–35 HRC soft | ~32 HRC in condition A | Annealed ~22 HRC |
| Relative material cost | Highest | Medium | Lowest |
| Specify it when | You need maximum strength with a straight part, or a weldable high-strength joint | Corrosion matters and 1,170 MPa is enough | Cost governs and the section can survive a quench |
We forge all three. See 17-4PH forgings, 15-5PH forgings and PH13-8Mo forgings.
Equivalent designations for Vascomax C250
| System | Designation |
|---|---|
| UNS (USA) | K92890 |
| Aerospace material spec | AMS 6512, for bar, forgings and tubing |
| ASTM | A538 Grade B |
| US military | MIL-S-46850, Grade 250 |
| Werkstoff Nr. (Germany) | 1.6359 |
| DIN / EN name | X2NiCoMo18-8-5 |
| China (GB) | 18Ni(250) / 00Ni18Co8Mo5TiAl |
| Generic names | Maraging 250, Maraging steel 250, Grade 250, 18Ni-250, 18% Ni maraging steel |
| Trade names | Vascomax® C250, VascoMax® C-250, Marvac® 250, NiMark® 250, Marval® 18H (nearest) |
Designations marked "nearest" are close but not identical matches; check the composition limits against your specification. Vascomax and VascoMax are registered trademarks of Carpenter Technology Corporation. Jiangyin Jiangnan Metal Co., Ltd. is not affiliated with the trademark holder, and these names are used here only to identify an equivalent material specification. Order to UNS K92890 and AMS 6512 to avoid ambiguity.
Vascomax C250 forgings we produce
Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory. Everything below is forged to your drawing or dimensional sketch. Open-die work needs no dies, so there is no tooling charge and no minimum order quantity by piece, so a single prototype ring is economic to produce.
Size and weight capability
| Product form | Dimensional range | Unit weight |
|---|---|---|
| Seamless rolled rings | OD 200–3,000 mm, height to 800 mm | 20–8,000 kg |
| Round bars | Ø80–800 mm, length to 6,000 mm | 20–6,000 kg |
| Discs and tube sheets | Ø200–2,500 mm, thickness to 600 mm | 30–10,000 kg |
| Shafts, sleeves, blocks | To 6,000 mm long | To 10,000 kg |
Overall works capability is 80 mm to 6,000 mm and 10 kg to 15,000 kg. Maraging steel is supplied from vacuum-remelted or ESR ingot, so the practical top end for a single piece depends on available ingot size for the grade, so confirm heavy sections with us before you freeze the design. Machining allowance is normally 6–20 mm per surface unless your drawing states otherwise. Finish-machined parts to print are also available.
How we make Vascomax C250 forgings
- MeltingVIM + VAR double vacuum melting where AMS 6512 aerospace cleanliness is invoked. VIM + ESR, or EAF + VOD followed by ESR remelting, for tooling and general industrial work. Tell us which route your specification requires, since it affects both price and lead time.
- Ingot and billet verificationHeat chemistry checked by spectrometer against the AMS 6512 window before any material is heated, with particular attention to carbon, titanium and the residual limits on phosphorus and sulfur.
- Open-die forgingForged on 1, 3, 5 and 9 tonne hammers and a 5,000 tonne hydraulic press. Start 1,150–1,260 °C, finish above 815 °C, reduction ratio 3:1 or greater. Rings are ring-rolled seamless. Air cooled after forging.
- Solution annealing815 °C, one hour per 25 mm of section, air cooled, to give uniform soft martensite at 30–35 HRC.
- Rough machiningTurned, bored and faced to your drawing with the agreed allowance, or to final dimensions where we supply finish-machined parts.
- Ageing, when ordered aged482 °C for 3–6 hours, air cooled, to 48–52 HRC. Furnace charts supplied with the certificate. Most customers take material annealed and age it themselves after machining.
- Non-destructive testingUltrasonic examination to EN 10228-3, SEP 1921 or ASTM A388 to your nominated class. Magnetic particle inspection to ASTM E1444, dimensional inspection and hardness survey as required.
- Certification and despatchEN 10204 3.1 mill test certificate as standard; 3.2 witnessed by TÜV, BV, LR, SGS or DNV on request. Heat number hard stamped, preserved against corrosion, packed for sea or air freight.
Where Vascomax C250 forgings are used
| Industry | Components | Why C250 |
|---|---|---|
| Aerospace structures | Landing gear components, actuator bodies and rods, torque tubes, wing-fold and flap fittings, helicopter flexible drive shafts | Highest strength-to-weight with fracture toughness retained |
| Space and launch | Solid rocket motor cases, thrust structure fittings, pressure vessel components | Thin sections that could not survive a quench; weldable at strength |
| Tooling and dies | Aluminium extrusion dies, die-casting inserts and cores, cold heading and cold extrusion dies, punches, plastic injection cores | Hardens without distortion; weld-repairable many times over tool life |
| Motorsport and drivetrain | Transmission and pinion shafts, half shafts, CV joints, gear blanks, clutch components | Maximum torque capacity in minimum diameter |
| Precision machinery | Index and lead screws, load-cell elements, high-load couplings, flexures, springs, mandrels | Dimensional stability through hardening; high elastic limit |
| Oil, gas and subsea | High-strength shafts, tie rods and fasteners, running tools | Strength with better stress-corrosion behaviour than Q&T steel of equal strength, when coated |
| General industrial | Ultrasonic transducer horns, high-load bolting, hydraulic rams | Fatigue strength and low acoustic loss |
Maraging steels are classified as controlled items under the export-control regulations of several jurisdictions. Tell us the destination country and end use at enquiry stage and we will supply the documentation your import authority and ours require.
When not to use Vascomax C250
C250 is expensive and specialised, and it is specified wrongly more often than most grades. It is not a high-temperature alloy, and it is not corrosion resistant. If your requirement is one of the following, another material will serve you better and we will say so on the quotation.
| Requirement | Why C250 fails | Specify instead |
|---|---|---|
| Sustained service above 400 °C | Approaches its own ageing temperature; over-ages and loses strength above 510 °C | Inconel 718, Waspaloy, Rene 41 |
| Combustor cans, flame holders, afterburner liners, transition ducts | These run at red heat. C250 has no useful strength there | Hastelloy X, Haynes 230, Haynes 188 |
| Wet, marine or chemical service without a coating | Not stainless. Rusts like a low-alloy steel | 17-4PH, PH13-8Mo, Monel K-500 |
| Sour service with H₂S exposure | Hardness far exceeds the NACE MR0175 / ISO 15156 limits | Incoloy 925, Inconel 725 |
| Cost-driven parts below about 1,500 MPa yield | Pays a large premium for strength the design does not use | AISI 4340, 300M or 4140, from our alloy steel range |
| Hot-work tooling running above 400 °C | Over-ages in service and softens | H13 or H11, from our tool steel range |
Testing, inspection and certification
- Chemical analysis. Spectrometric ladle analysis on every heat, with carbon and sulfur by combustion. Product analysis on the finished forging on request.
- Mechanical testing. Room-temperature tensile and elongation to ASTM E8/E8M or ISO 6892-1, in the delivery condition and, where ordered, on separately aged test coupons.
- Hardness. Rockwell C to ASTM E18, with a multi-point survey across the section on heavy forgings.
- Impact testing. Charpy V-notch to ASTM E23 or ISO 148-1, at the orientation you nominate.
- Fracture toughness. Plane-strain KIC to ASTM E399 where your specification calls for it.
- Ultrasonic testing. EN 10228-3, SEP 1921 Class C/D/E, ASTM A388, or your nominated class.
- Magnetic particle inspection. ASTM E1444 or ASME Section V Article 7. C250 is ferromagnetic, so MT is available in addition to liquid penetrant to ASTM E165.
- Grain size and cleanliness. ASTM E112 grain size; ASTM E45 or DIN 50602 microcleanliness rating.
- Heat treatment records. Furnace charts for the solution anneal and, where ordered aged, for the ageing cycle.
- Certification. EN 10204 3.1 as standard, showing heat number, chemical analysis, mechanical results, heat treatment record and NDT results. EN 10204 3.2 witnessed by TÜV, BV, LR, SGS or DNV on request at order stage. Full heat traceability with hard stamping.
Vascomax C250 engineering tools
Five calculators for specifying and buying C250. Everything runs in your browser; nothing is sent anywhere until you choose to email us.
1. Ageing cycle planner
Predicts the hardness and yield strength you should expect from a given ageing cycle, after a correct 815 °C solution anneal.
2. Designation lookup
Type a UNS number, Werkstoff number, specification or trade name and find out which maraging grade it is. Try K92890, 1.6359, AMS 6512 or Marvac 250.
3. Grade chooser
Three questions. Tells you whether C250 is the right grade for your part, or which of ours is.
4. Forging weight calculator
Finished and rough-forged weight at the C250 density of 8.00 g/cm³. Useful for budgeting before you have a drawing.
5. Enquiry builder
Fill in what you know and the button below opens a complete, correctly formatted enquiry in your mail client. Nothing is submitted from this page.
Frequently asked questions about Vascomax C250
Is Vascomax C250 a nickel alloy or a steel?
It is a steel. Vascomax C250 is an iron-based maraging steel: iron is the balance at roughly 65–70%, with 17–19% nickel, 7–8.5% cobalt and 4.6–5.2% molybdenum. It is not a nickel-base superalloy like Inconel or Hastelloy, and it has none of their high-temperature capability. The confusion is common because of the high nickel content, and because suppliers, including this site, often catalogue it alongside the nickel alloys. If your specification calls for a nickel-base alloy, C250 will not satisfy it.
What is the yield strength of Vascomax C250?
1,725 MPa (250 ksi) minimum in the solution annealed and aged condition, with tensile strength of 1,860 MPa (270 ksi) minimum and hardness of 48–52 HRC. The number in the grade name is the yield strength in ksi, which is why the family runs C200, C250, C300 and C350. In the solution annealed condition, before ageing, yield strength is only 760–830 MPa and hardness 30–35 HRC.
What heat treatment does Vascomax C250 need?
Solution anneal at 815 °C (1500 °F) for one hour per 25 mm of section and air cool, which gives soft martensite at 30–35 HRC. Machine the part in that condition, then age at 482 °C (900 °F) for three to six hours and air cool, which gives 48–52 HRC. There is no quench and no temper. Do not exceed 510 °C during ageing: above that temperature the martensite reverts to austenite and strength falls, and the only remedy is a full re-solution anneal.
Can Vascomax C250 be welded?
Yes, and unusually well for a steel at this strength level. It can be welded by GTAW, electron beam, laser or plasma, in either the annealed or the fully aged condition, with no preheat, because the carbon content is too low to form a brittle heat-affected zone. Use a matching maraging filler, keep heat input low, and re-age at 482 °C for three to six hours after welding to restore strength across the joint. For full parent-metal properties, re-solution anneal at 815 °C and then age.
Is Vascomax C250 corrosion resistant?
No. It is not a stainless steel and it rusts in humid air much as a low-alloy steel does. Its one advantage is that it resists stress-corrosion cracking somewhat better than a quenched and tempered steel of the same strength. In service it needs a barrier: cadmium or zinc-nickel plating, phosphate and oil, nitriding, or paint. If the bare surface must survive a corrosive environment, specify 17-4PH, PH13-8Mo or Custom 465 instead.
What is the maximum service temperature of Vascomax C250?
About 400 °C (750 °F) for continuous service. The limit is set by the ageing temperature: at 482 °C the alloy is being deliberately transformed, and above roughly 510 °C reverted austenite forms and strength falls permanently. Keeping service below 400 °C leaves a safe margin. For anything running hotter, specify a nickel-base alloy such as Inconel 718, Waspaloy or Rene 41.
What is the difference between Vascomax C250 and C300?
The main difference is titanium content. C250 carries 0.30–0.50% titanium and reaches 1,725 MPa yield at 48–52 HRC. C300 carries 0.55–0.80% titanium and slightly more cobalt, and reaches about 2,000 MPa yield at 51–55 HRC. Nickel, molybdenum and the 0.03% carbon ceiling are the same, and both use the same heat treatment. C300 pays for its extra strength with lower impact energy, lower fracture toughness, more sensitivity to section size and a narrower welding window. C250 is the better choice unless the design genuinely needs the extra 275 MPa.
Does Vascomax C250 change size when it is aged?
Yes, it contracts by roughly 0.04 to 0.08%, or 0.4 to 0.8 millimetres per metre. The contraction is uniform and predictable, which is one reason the grade is chosen for parts that cannot tolerate quench distortion. Standard practice is to rough machine in the annealed condition leaving 0.25–0.5 mm of stock per surface, age, then finish grind or turn.
Which melting route should I specify?
VIM + VAR, vacuum induction melting followed by vacuum arc remelting, is the normal route where AMS 6512 aerospace cleanliness is invoked, and it is what most aerospace and defence specifications require. VIM + ESR, or EAF + VOD followed by ESR remelting, is used for tooling and general industrial work at lower cost. The routes differ substantially in price and lead time, so state which one your specification requires when you enquire rather than after the order is placed.
What sizes of Vascomax C250 forgings can you supply?
Jiangyin Jiangnan Metal forges rolled rings from 200 to 3,000 mm outside diameter, round bars from Ø80 to Ø800 mm and up to 6,000 mm long, discs and tube sheets to Ø2,500 mm, and shafts, sleeves and blocks up to 6,000 mm long, at unit weights from 20 to 10,000 kg. Overall works capability is 80–6,000 mm and 10–15,000 kg. Because maraging steel comes from vacuum-remelted or ESR ingot, the top end for a single piece depends on the ingot available for this grade, so confirm heavy sections with us before freezing the design.
Do you supply a material certificate?
Every Vascomax C250 forging ships with an EN 10204 3.1 mill test certificate showing heat number, chemical analysis, mechanical test results, heat treatment record and NDT results. EN 10204 3.2 certification witnessed by a third party such as TÜV, BV, LR, SGS or DNV is available on request at the time of order. Heat numbers are hard stamped for full traceability.
Is there a minimum order quantity?
No. Open-die forging needs no dies, so there is no tooling charge and no minimum piece count. A single prototype ring or shaft is economic to produce. What does govern cost is the ingot: for a small part in a grade like C250, the minimum practical purchase is set by the smallest available remelted ingot, so very small single pieces can carry a high unit cost. Send us the size and we will tell you whether forging or bar stock is the cheaper route.
How long does a Vascomax C250 forging take?
It depends on whether suitable remelted stock is available and on the size of the piece. Simple rings and discs from stock material typically run 25–40 days. Parts needing a new melt, VIM + VAR processing, heavy machining or third-party witnessed inspection take longer. Send a drawing and we will confirm a firm date with the quotation.
Who supplies open-die forged Vascomax C250 parts in China?
Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China. It forges Vascomax C250 and the other 18Ni maraging grades, along with nickel alloys, stainless steels, tool steels, alloy steels and carbon steels, into seamless rolled rings, discs, shafts, bars, flanges, sleeves and tube sheets, and exports worldwide. Enquiries: sales@steelforgepieces.com or +86 189 2135 9659.
Request a quotation for Vascomax C250 forgings
Send a drawing, a sketch, or the dimensions and quantity. We quote open-die forgings in Vascomax C250 with no tooling charge and no piece minimum.
Useful details if you have them: grade and standard, product form, dimensions with machining allowance, quantity, delivery condition, melting route, NDT class, certificate type and required delivery date. The enquiry builder above will assemble all of this for you.
- Company
- Jiangyin Jiangnan Metal Co., Ltd.
- Business
- Open-die forging factory
- Address
- No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China
- Telephone / WhatsApp
- +86 189 2135 9659
- Website
- www.steelforgepieces.com