Datasheet last reviewed: 28 August 2026. Published by Jiangyin Jiangnan Metal Co., Ltd.
Overview
What UNS K93160 is, and when to specify it
UNS K93160 is the strongest of the three common 18% nickel maraging steels. It sits one step above Maraging 300 (UNS K93120) and two above Maraging 250 (UNS K92890).
Maraging steels harden by a different mechanism from ordinary steel. Conventional high-strength steels rely on carbon, which forms hard but brittle carbides and forces a quench that distorts the part. UNS K93160 carries almost no carbon. It hardens instead when a soft iron-nickel martensite is aged, so that intermetallic compounds precipitate through the matrix, mainly Ni3Mo, Fe2Mo and Ni3Ti. Cobalt forms no precipitate of its own. It lowers the solubility of molybdenum in the matrix and drives the precipitation reaction, which is why cobalt content is what separates the 250, 300 and 350 grades.
For a forging buyer the practical result is the sequence below. The alloy arrives soft enough to machine with ordinary carbide tooling. It only becomes ultra-hard in a final low-temperature furnace cycle that causes very little distortion and needs no protective atmosphere.
As supplied, solution annealed
30-35HRC
UTS approx. 1000-1100 MPa
- Machines with standard carbide tooling
- Formable, drillable, weldable
- Finish all machining at this stage
After ageing
56HRC max
UTS 2345 MPa / 340 ksi min
- Small, uniform, predictable shrinkage
- No quench, no protective atmosphere
- Grind, EDM or nitride after ageing
When to specify UNS K93160
- Yield strength above 2200 MPa is required and Maraging 300 does not reach it.
- The part is complex or thin-walled and would not survive the distortion of a quench and temper cycle.
- Resistance to crack propagation matters more than absolute ductility.
- The part has to be welded and then brought back to full strength by re-ageing.
When another grade suits better
- The part needs corrosion resistance. UNS K93160 is not stainless, as covered in the FAQ.
- Elongation above roughly 6 to 8% is required. Maraging 300 and 250 trade strength for ductility.
- Service temperature goes above about 400 °C, where the precipitates over-age and strength drops.
- Cost decides the job. At 12% cobalt this is the most expensive of the three grades.
Cross-reference
UNS K93160 equivalents and specifications
The same alloy is sold under at least six names. If a drawing calls out any designation below, UNS K93160 is the material to order.
| System | Designation |
|---|---|
| UNS | K93160 |
| Common name | Maraging 350, Maraging C350, 18Ni(350), 18Ni-350 |
| Trade names | Vascomax® 350, AlMar® 350 |
| SAE / AMS | AMS 6515 |
| US military | MIL-S-46850 |
| Werkstoff (DIN / EN) | 1.6356 |
| EN steel name | X2NiCoMoTi 18-12-4 |
| Nearest lower grade | Maraging 300: UNS K93120, AMS 6514, 1.6358 |
| Two steps down | Maraging 250: UNS K92890, AMS 6512, 1.6359 |
Vascomax and AlMar are registered trademarks of their respective owners, listed here only to identify equivalent material.
Chemistry
UNS K93160 chemical composition
Limits below follow AMS 6515 and MIL-S-46850, in weight percent, with iron as the balance. The four elements that do the work are nickel, cobalt, molybdenum and titanium.
| Element | Min | Max | Nominal | Function in the alloy |
|---|---|---|---|---|
| Nickel (Ni) | 18.00 | 19.00 | 18.50 | Forms the soft, tough iron-nickel martensite matrix that makes ageing possible |
| Cobalt (Co) | 11.50 | 12.50 | 12.00 | Primary strengthening agent. Lowers Mo solubility and drives precipitation |
| Molybdenum (Mo) | 4.60 | 5.20 | 4.80 | Forms the Ni3Mo and Fe2Mo precipitates that carry the strength |
| Titanium (Ti) | 1.30 | 1.60 | 1.40 | Forms Ni3Ti. Main chemical difference from Maraging 300 |
| Aluminium (Al) | 0.05 | 0.15 | 0.10 | Deoxidiser. Also contributes to the age-hardening response |
| Carbon (C) | - | 0.030 | 0.01 max | Held very low. Carbides would embrittle the alloy and spoil weldability |
| Silicon (Si) | - | 0.10 | - | Residual, restricted to protect toughness |
| Manganese (Mn) | - | 0.10 | - | Residual, restricted to avoid grain-boundary embrittlement |
| Phosphorus (P) | - | 0.010 | - | Residual impurity |
| Sulphur (S) | - | 0.010 | - | Residual impurity |
| Chromium (Cr) | - | 0.50 | - | Residual only. Far too low to give stainless behaviour |
| Copper (Cu) | - | 0.50 | - | Residual |
| Boron (B) | - | 0.003 | 0.003 | Grain refiner, added in trace amounts |
| Zirconium (Zr) | - | 0.02 | 0.01 | Grain refiner, added in trace amounts |
| Iron (Fe) | Balance, approx. 63% | Matrix | ||
The number that identifies the grade is cobalt. UNS K93160 (Maraging 350) carries 11.5 to 12.5% Co and 1.30 to 1.60% Ti. UNS K93120 (Maraging 300) carries about 8.5 to 9.5% Co and 0.5 to 0.8% Ti. If a mill certificate shows around 9% cobalt, the material is Maraging 300 and will not reach 340 ksi whatever the heat number says. Check Co and Ti on the certificate before releasing material to ageing.
Properties
UNS K93160 mechanical and physical properties
Values below are for the fully aged condition unless stated otherwise. Room-temperature properties are tested on the forging itself and reported on the material certificate against the heat number.
| Property | Metric | Imperial | Condition |
|---|---|---|---|
| Tensile strength, Rm | 2345 MPa min | 340 ksi min | Aged |
| Yield strength, Rp0.2 | 2275 MPa min | 330 ksi min | Aged |
| Elongation, A | 3% min | 3% min | Aged |
| Hardness | 56 HRC max | - | Aged |
| Hardness | 30-35 HRC | - | Solution annealed |
| Tensile strength | approx. 1000-1100 MPa | approx. 145-160 ksi | Solution annealed |
| Modulus of elasticity, E | approx. 186 GPa | approx. 27 x 103 ksi | Typical |
| Density | 8.0 g/cm3 | 0.289 lb/in3 | All conditions |
| Magnetic response | Ferromagnetic | All conditions | |
Reduction of area, Charpy impact energy, KIC fracture toughness and elevated-temperature data are reported per order on request. Tell us the acceptance criteria at enquiry stage so test blocks and orientation are planned into the forging.
How UNS K93160 compares with the other maraging grades
| Grade | UNS | Co, % | Ti, % | Aged UTS | Elongation |
|---|---|---|---|---|---|
| Maraging 250 | K92890 | 7.0-8.5 | 0.30-0.50 | approx. 1750 MPa | approx. 8% |
| Maraging 300 | K93120 | 8.5-9.5 | 0.50-0.80 | approx. 2050 MPa | approx. 6% |
| Maraging 350 | K93160 | 11.5-12.5 | 1.30-1.60 | 2345 MPa min | 3% min |
Elongation and toughness fall as cobalt and titanium rise. Where a design has margin on strength, Maraging 300 is usually the more forgiving and less expensive choice.
Processing
Heat treatment of UNS K93160 forgings
UNS K93160 needs two furnace operations and neither involves a quench. Forgings normally ship solution annealed so the customer can machine them, then get aged either by the customer or by us before delivery.
| Step | Temperature | Time | Cooling and result |
|---|---|---|---|
| Solution anneal | 815-830 °C 1500-1525 °F |
approx. 1 h per 25 mm of section |
Air cool. Produces soft, machinable iron-nickel martensite at 30 to 35 HRC. |
| Age | 480 °C 900 °F |
3-6 h | Air cool. Precipitation hardening to full strength, 56 HRC max. |
| Stress relief, optional |
480 °C 900 °F |
1-3 h | Air cool. Doubles as a re-age after welding or heavy machining. |
Points that matter in practice
- No protective atmosphere is required. With almost no carbon in the alloy there is nothing to decarburise, so annealing and ageing run in air. Light oxide comes off by pickling or blasting.
- Ageing shrinks the part slightly. Linear contraction is small, uniform and repeatable, well under 0.1%, but it is not zero. Allow for it on close-tolerance features, or finish-grind after ageing.
- Finish machining before ageing. At 30 to 35 HRC the alloy machines conventionally. At 56 HRC only grinding, EDM and hard-turning are practical.
- Do not over-age. Holding much beyond the specified time, or ageing above roughly 510 °C, reverts martensite to austenite and drops the strength.
Forging parameters
UNS K93160 is forged from a soaking temperature of about 1150-1200 °C, finishing above roughly 900 °C to avoid cracking, then air cooled and solution annealed. Reduction ratio and finishing temperature are controlled so grain flow follows the part contour, around the circumference for rings and along the axis for shafts.
Fabrication
Machining, welding and surface treatment
Machining
In the solution-annealed condition UNS K93160 machines much like a 300-series stainless. It work-hardens, so use positive-rake carbide tooling, rigid setups, generous depth of cut and a steady feed rather than light dwelling passes. Rough and finish everything before ageing wherever the tolerance allows. After ageing, plan on grinding, wire or sinker EDM, or hard-turning with CBN.
Welding
UNS K93160 welds readily by GTAW/TIG, electron beam and laser, using matching filler. With virtually no carbon in the alloy there is no preheat requirement and no hydrogen cracking mechanism to guard against. Weld metal and heat-affected zone come out in the soft annealed state, so a re-age at 480 °C after welding restores strength across the joint. Keep the joint clean and the heat input low to limit the size of the reverted-austenite zone.
Surface treatment
UNS K93160 is not corrosion resistant and needs protection in service. Common options are nitriding, which the alloy takes readily and which gives a very hard case, plus plating, phosphating, painting or dry-film lubricant. Hydrogen-charging processes such as acid pickling and electroplating call for a post-plate bake, since ultra-high-strength steels are sensitive to hydrogen embrittlement.
Product range
UNS K93160 forged forms we manufacture
Every item below is open-die forged or ring-rolled to the customer drawing. There are no stock catalogue sizes. Send a drawing or a rough envelope with a quantity and we quote against it.
Forged rings
Open-die forged rings in UNS K93160, upset and punched from a solid billet.
Seamless rolled rings
Ring-rolled so grain flow follows the circumference, which is what a hoop-loaded part needs.
Forged discs and blanks
Solid discs and blanks for gears, hubs, closures and cover plates.
Forged shafts
Straight, stepped and eccentric shafts, spindles and transmission shafting.
Forged round bars
Forged and peeled or rough-turned bar in the annealed condition.
Forged flanges
Flanges and flanged bodies forged to drawing.
Sleeves and bushings
Hollow forged sleeves, bushings and liners, bored and faced.
Tube sheets
Forged tube sheets and thick plate blanks for heat exchangers.
Forged blocks and slabs
Rectangular blocks for die and tooling applications.
Hollow bars and forged tubes
Bored hollow forgings where a rolled ring is not the right geometry.
Gear blanks
Forged blanks for gears, pinions and couplings.
Near-net shapes
Contoured forgings that cut machining time and buy-to-fly ratio.
Typical open-die capability
| Item | Range |
|---|---|
| Single-piece weight | 20 kg to 15 000 kg |
| Rolled ring outside diameter | 300 to 3000 mm |
| Ring wall and height | up to 800 mm |
| Round bar and shaft diameter | 80 to 1200 mm |
| Maximum length | up to 8000 mm |
| Disc diameter | up to 2500 mm |
| Order quantity | Single prototype pieces to series production |
Maraging steel is normally ordered in smaller sections than carbon or alloy steel. If your part sits outside this envelope, send the drawing anyway and we will tell you whether it is inside our capability.
Manufacturing and QA
How UNS K93160 forgings are made and verified
Melting route
UNS K93160 is a clean-steel alloy. Titanium and aluminium at these levels oxidise in air melting, and inclusion content governs the fatigue and toughness of a 2300 MPa material. Two routes are available.
- VIM plus VAR. Vacuum induction melting followed by vacuum arc remelting. This is the route specified by AMS 6515 and required for aerospace and defence work.
- EAF plus LF plus VD plus ESR. Electric arc furnace, ladle refining, vacuum degassing and electroslag remelting. A lower-cost route suited to industrial tooling and general engineering parts.
State the required melting route on the enquiry. It has a large effect on both price and lead time, and a forging melted the wrong way cannot be re-certified afterwards.
Non-destructive testing
| Test | Standard | Purpose |
|---|---|---|
| Ultrasonic testing | EN 10228-3, SEP 1921, ASTM A388 | Internal soundness, acceptance class agreed at order |
| Magnetic particle | ASTM E709, EN 10228-1 | Surface and near-surface indications |
| Liquid penetrant | ASTM E165 | Surface indications on machined faces |
| Chemical analysis | Spectrographic, per heat | Verifies Ni, Co, Mo and Ti against AMS 6515 |
| Mechanical testing | ASTM E8 / ISO 6892, ASTM E18 | Tensile, elongation and hardness on the forging |
| Dimensional | Per drawing | Full report against the customer drawing |
Certification and traceability
Every UNS K93160 forging ships with a mill test certificate to EN 10204 3.1, issued against the heat number and covering chemistry, heat treatment condition, mechanical results and NDT results. Where the order requires it, EN 10204 3.2 certification is issued with the third-party inspection body of your choice witnessing the tests. Heat numbers are hard-stamped or vibro-etched on the part so traceability survives machining.
Export control notice. Maraging steels capable of a tensile strength of 1950 MPa or more are listed dual-use items under the Nuclear Suppliers Group control lists and the corresponding national regulations, for example ECCN 1C216 in the United States and entry 1C216 in the EU dual-use list. UNS K93160 is well above that threshold. Orders are accepted subject to end-use and end-user documentation and to any export licensing required in the countries of shipment and destination. Please raise this at enquiry stage so that lead time can be planned realistically.
Applications
Where UNS K93160 forgings are used
UNS K93160 is chosen where strength-to-weight ratio decides the design, and where a part is too complex to survive a conventional quench.
| Sector | Components |
|---|---|
| Aerospace and defence | Rocket motor cases, missile bodies, landing and take-off gear components, actuator housings, structural fittings |
| Tooling and die | Die-casting dies, extrusion tooling, cold-forming punches and mandrels, die holders, moulds |
| Power transmission | High-performance shafting, gears, pinions, couplings, spindles, torsion members |
| Motorsport and high performance | Transmission shafts, gearbox internals, driveline and suspension components |
| Oil, gas and subsea | High-pressure body and stem components, wellhead parts, tools for tight annulus applications |
| Industrial and general | Ultra-high-strength fasteners, springs, load cells, flexures, hydraulic press components |
UNS K93160 has no useful corrosion resistance, so applications in wet or marine service always pair it with a coating, plating or cathodic protection scheme.
Ordering
How to request a quotation for UNS K93160 forgings
Send a drawing, or a rough envelope with the finished dimensions, to sales@steelforgepieces.com. A quotation normally comes back within 24 hours. The more of the following you give us at the start, the fewer rounds of questions it takes.
| Item | Why we ask |
|---|---|
| Drawing or dimensions | Sets the forging weight, the die work and the machining allowance |
| Quantity and schedule | Decides whether the heat is dedicated or shared, which drives price |
| Delivery condition | As-forged, solution annealed, or fully aged and finish-machined |
| Governing specification | AMS 6515, MIL-S-46850 or your own internal spec |
| Melting route | VIM plus VAR, or EAF plus LF plus VD plus ESR. Significant price and lead-time effect |
| NDT scope and class | UT acceptance class per EN 10228-3 or ASTM A388, plus MT and PT if required |
| Certificate type | EN 10204 3.1, or 3.2 with a named third-party inspector |
| Destination and end use | Required for export-control screening on maraging grades |
Email the drawing to sales@steelforgepieces.com Call +86 189 2135 9659
FAQ
UNS K93160 frequently asked questions
What is UNS K93160?
UNS K93160 is a cobalt-strengthened 18% nickel maraging steel, sold in most markets as Maraging 350, 18Ni(350) or C350. It runs about 18.5% nickel, 12% cobalt, 4.8% molybdenum and 1.4% titanium, with carbon held under 0.03%. It is covered by AMS 6515 and MIL-S-46850, and by Werkstoff number 1.6356. After a low-temperature ageing treatment it reaches a tensile strength above 2300 MPa, which puts it among the strongest steels in commercial production.
Is UNS K93160 the same as Maraging 350?
Yes. UNS K93160 is the UNS designation for Maraging 350. The same alloy is also sold as 18Ni(350), Maraging C350, Vascomax® 350 and AlMar® 350, and appears in European standards as Werkstoff 1.6356 / X2NiCoMoTi 18-12-4. The governing specifications are AMS 6515 and MIL-S-46850.
What is the difference between UNS K93160 and UNS K93120?
Cobalt and titanium content. UNS K93160 (Maraging 350) contains 11.5 to 12.5% cobalt and 1.30 to 1.60% titanium. UNS K93120 (Maraging 300) contains about 8.5 to 9.5% cobalt and 0.5 to 0.8% titanium. The higher cobalt and titanium raise the aged tensile strength from around 2050 MPa for Maraging 300 to at least 2345 MPa for Maraging 350, at the cost of lower ductility and toughness.
What tensile strength does UNS K93160 reach?
In the aged condition UNS K93160 reaches a minimum tensile strength of 2345 MPa (340 ksi) and a minimum 0.2% yield strength of 2275 MPa (330 ksi), with elongation of at least 3% and hardness up to 56 HRC. In the solution-annealed condition, as it is normally supplied for machining, it is far softer at 30 to 35 HRC.
What heat treatment does UNS K93160 need?
Two steps. First a solution anneal at 815 to 830 °C (1500 to 1525 °F), held about one hour per 25 mm of section, then air cool, which leaves the part soft and machinable at 30 to 35 HRC. Then age at 480 °C (900 °F) for 3 to 6 hours and air cool. With almost no carbon in the alloy no protective atmosphere is required, and distortion during ageing is small and predictable.
Is UNS K93160 corrosion resistant or stainless?
No. Despite the high nickel content, UNS K93160 is not a stainless steel. Chromium is limited to 0.50% maximum, so it corrodes in the same way as a low-alloy steel. Parts in service normally require plating, painting, phosphating, nitriding or another protective coating. It is also ferromagnetic, because its structure is iron-nickel martensite.
Can UNS K93160 be supplied as a seamless rolled ring?
Yes. Jiangyin Jiangnan Metal Co., Ltd. produces UNS K93160 as seamless rolled rings, open-die forged rings, discs, shafts, round bars, flanges, sleeves, bushings and tube sheets, forged to the customer drawing. Rings are ring-rolled from an upset and punched preform so that grain flow follows the circumference, which is what a hoop-loaded ring needs.
Who manufactures UNS K93160 forgings?
Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China that manufactures UNS K93160 (Maraging 350) forgings to customer drawings. The company supplies forged rings, seamless rolled rings, discs, shafts, bars and flanges with EN 10204 3.1 or 3.2 certification and ultrasonic testing to EN 10228-3, SEP 1921 or ASTM A388. Enquiries go to sales@steelforgepieces.com or +86 189 2135 9659.
What information is needed to quote a UNS K93160 forging?
Send the drawing or the rough dimensions, the quantity, the delivery condition you need (as-forged, solution annealed or fully aged), the governing specification, the melting route required, the non-destructive testing scope and acceptance class, and the certificate type. With a drawing and a quantity a quotation normally comes back within 24 hours.
Is maraging steel export controlled?
Yes, in most jurisdictions. Maraging steels capable of a tensile strength of 1950 MPa or more are listed dual-use items under the Nuclear Suppliers Group control lists and equivalent national regulations, for example ECCN 1C216. UNS K93160 is well above that threshold, so orders are accepted subject to end-use documentation and any export licensing that applies in the countries of shipment and destination.
Manufacturer
About Jiangyin Jiangnan Metal Co., Ltd.
Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory located at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China. The company forges rings, seamless rolled rings, shafts, discs, bars, flanges, sleeves, bushings and tube sheets to customer drawings in carbon steel, alloy steel, tool steel, stainless steel, nickel alloys and maraging steels including UNS K93160.
Jiangyin sits in the Yangtze River delta, about 150 km from Shanghai and 100 km from Shanghai Pudong and Wuxi Sunan airports, with the Port of Jiangyin on the Yangtze immediately to the north. That keeps freight cost and transit time down on export orders.
Work is supplied with EN 10204 3.1 material certificates as standard, or EN 10204 3.2 with third-party witness where the order requires it, and with ultrasonic testing to EN 10228-3, SEP 1921 or ASTM A388.
| Company | Jiangyin Jiangnan Metal Co., Ltd. |
|---|---|
| Business | Open-die forging factory, forgings made to drawing |
| Address | No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China |
| Telephone | +86 189 2135 9659 |
| sales@steelforgepieces.com | |
| Website | www.steelforgepieces.com |
| Materials | Carbon steel, alloy steel, tool steel, stainless steel, nickel alloys, maraging steels |
| Certification | EN 10204 3.1 standard, EN 10204 3.2 on request |