Steel 18Ni(350) Maraging Steel
UNS K93160 · AISI/SAE 18Ni350 · also Vascomax C350
18Ni(350) maraging steel (K93160, Vascomax C350) is the highest-strength commercial grade of the Fe-18Ni-Co-Mo maraging family, hardened by aging at 480 °C after solution annealing.
Reference datasheet — 18Ni(350) Maraging Steel is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the Aged condition
18Ni(350) Maraging Steel tempers and conditions
18Ni(350) Maraging Steel is supplied in 4 conditions, soft to hard. Aged is the default FabDigit quotes; the values on this page are for it.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Solution annealed | Soft as-supplied/annealed condition for machining, cold forming and welding before final aging. | 830 | 1,140 | 17 | 32 HRC | 25 W/m·K |
SA + cold drawn/rolled | Cold-worked annealed stock for wire, thin strip and precision bar; cold work raises pre-age strength and slightly boosts final aged strength. | 1,150 | 1,300 | 8 | 38 HRC | 3.4 % IACS |
Overaged / toughness-optimized age | Slightly overaged cycle trading ~150–250 MPa of strength for better ductility and K_IC in fracture-critical parts. | 2,100 | 2,200 | 9 | 53 HRC | 3.9 % IACS |
AgedDefault 480 °C / 3–6 h, air cooled | Standard delivered/final condition: peak ~2400 MPa strength with minimal distortion; pick when extreme static strength governs and toughness demands are moderate. | 2,320 | 2,400 | 7 | 56 HRC | 20 W/m·K |
What is 18Ni(350) Maraging Steel?
18Ni(350) maraging steel (K93160, Vascomax C350) is the highest-strength commercial grade of the Fe-18Ni-Co-Mo maraging family, hardened by aging at 480 °C after solution annealing. Aged properties are 2320 MPa yield, 2400 MPa tensile, 7% elongation, 56 HRC and 190 GPa modulus, chosen where extreme static strength outweighs toughness; usual forms are vacuum-melted bar and plate. Machinability (22) and formability (10) are poor, weldability is moderate (55), corrosion resistance is low (28) and service is capped at 400 °C. Use 18Ni(200) or 18Ni(250) when toughness and joinability matter more. 18Ni(350) Maraging Steel has a density of 8.08 g/cm³ (0.292 lb/in³), heavier than 96% of steel grades. It melts at 1,413°C (2,575 °F). 18Ni(350) Maraging Steel has a yield strength of 2,320 MPa (336 ksi) and a tensile strength of 2,400 MPa (348 ksi) — stronger than 100% of steel grades. Elongation at break is 7% and the elastic modulus is 190 GPa (27.6 Msi).
What is 18Ni(350) Maraging Steel used for?
- rocket motor casings
- high-strength shafts
- aerospace fasteners
Advantages
- High strength — 2,320 MPa (336 ksi), better than 100% of steel grades
- Polishes to a fine finish — 80/100, better than 97% of steel grades
- Good corrosion resistance — 28/100, better than 94% of steel grades
Limitations
- High embodied carbon — 6.5 kg CO₂/kg, worse than 98% of steel grades
- Limited ductility — 7%, worse than 96% of steel grades
- Poor heat conductor — 20 W/m·K (11.6 BTU/hr·ft·°F), worse than 96% of steel grades
- Difficult to machine — 22/100, worse than 95% of steel grades
- Limited formability — 10/100, worse than 95% of steel grades
18Ni(350) Maraging Steel properties
Typical room-temperature values for 18Ni(350) Maraging Steel-Aged; bars are the position among steel grades.
Physical3
18Ni(350) Maraging Steel has a density of 8.08 g/cm³ (0.292 lb/in³), heavier than 96% of steel grades. It melts at 1,413°C (2,575 °F).
Mechanical15
18Ni(350) Maraging Steel has a yield strength of 2,320 MPa (336 ksi) and a tensile strength of 2,400 MPa (348 ksi) — stronger than 100% of steel grades. Elongation at break is 7% and the elastic modulus is 190 GPa (27.6 Msi).
Thermal6
18Ni(350) Maraging Steel is rated for continuous service to 400°C (752 °F). It conducts heat at 20 W/m·K (11.6 BTU/hr·ft·°F), worse than 96% of steel grades. Thermal expansion is 10.1 µm/m·K (5.61 µin/in·°F).
Electrical3
18Ni(350) Maraging Steel conducts electricity at 3.8 % IACS, worse than 84% of steel grades.
Chemical & Environmental3
Corrosion resistance is poor (28/100), better than 94% of steel grades.
Sustainability4
Producing a kilogram of 18Ni(350) Maraging Steel takes about 90 MJ of energy and emits 6.5 kg of CO₂ — more than 98% of steel grades. Typical recycled content is 20%.
Manufacturability8
18Ni(350) Maraging Steel's machinability is poor (22/100, worse than 95% of steel grades); weldability good (55/100); formability not recommended (10/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the steel family
Yield strength against density for every steel grade FabDigit runs. 18Ni(350) Maraging Steel is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 18Ni(350) Maraging Steel
Is 18Ni(350) Maraging Steel easy to machine?
Rough-machine in the annealed condition (≈50 % of 1212) leaving ~0.05 % growth allowance for aging; aged 54–58 HRC material needs CBN/ceramic tooling, grinding or EDM.
Can 18Ni(350) Maraging Steel be welded?
GTAW/EBW/laser with matching filler, no preheat, low heat input on clean solution-annealed material; re-age at 480 °C after welding to restore joint strength (soft reverted-austenite zone otherwise).
Can 18Ni(350) Maraging Steel be formed, bent or molded?
Cold form, bend and deep-draw only in the solution-annealed state; hot work 1150–900 °C, then solution anneal at 815 °C before aging — aged parts are effectively non-formable.
18Ni(350) Maraging Steel chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| Ni | 17.5 – 19 | 18.5 |
| Co | 11.5 – 12.5 | 12 |
| Mo | 4.6 – 5.2 | 4.9 |
| Tiprimary strengthener for 350 grade | 1.3 – 1.6 | 1.45 |
| Al | 0.05 – 0.15 | 0.1 |
| C | ≤ 0.03 | 0.01 |
| Si | ≤ 0.1 | |
| Mn | ≤ 0.1 | |
| P | ≤ 0.01 | |
| S | ≤ 0.01 | |
| Boptional grain-refining addition | ≤ 0 | |
| Zroptional | ≤ 0.02 | |
| Caoptional | ≤ 0.05 | |
| Fe | balance |
What surface finishes work on 18Ni(350) Maraging Steel?
Not anodizable; use cadmium, electroless nickel or hard chrome plating with a 190 °C hydrogen-relief bake, or passivate/paint; vacuum-melted stock polishes to a fine mold finish and nitrides well.
Surface treatments FabDigit runs on steel parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
Organic Coating
Black / Phosphate
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Steel 18Ni(350) Maraging Steel in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- K93160
- AISI / SAE
- 18Ni350
- Trade names
- Vascomax C350
- Also called
- Maraging 350
How much does 18Ni(350) Maraging Steel cost?
18Ni(350) Maraging Steel is a high-cost steel ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
18Ni(350) Maraging Steel — frequently asked
What is 18Ni(350) Maraging Steel used for?
18Ni(350) Maraging Steel is typically used for rocket motor casings, high-strength shafts and aerospace fasteners. In short: strongest 18Ni maraging grade; 2400 MPa tensile, 56 HRC; low ductility at 7% elongation.
What is the yield strength of 18Ni(350) Maraging Steel?
18Ni(350) Maraging Steel has a typical yield strength of 2,320 MPa (336 ksi) and a tensile strength of 2,400 MPa (348 ksi) — stronger than 100% of steel grades. Strength varies by condition: see the 4 listed tempers.
Is 18Ni(350) Maraging Steel easy to machine?
Not especially — machinability is rated poor (22/100, worse than 95% of steel grades). Rough-machine in the annealed condition (≈50 % of 1212) leaving ~0.05 % growth allowance for aging; aged 54–58 HRC material needs CBN/ceramic tooling, grinding or EDM.
Can 18Ni(350) Maraging Steel be welded?
Yes — weldability is rated good (55/100). GTAW/EBW/laser with matching filler, no preheat, low heat input on clean solution-annealed material; re-age at 480 °C after welding to restore joint strength (soft reverted-austenite zone otherwise).
What surface finishes work on 18Ni(350) Maraging Steel?
Not anodizable; use cadmium, electroless nickel or hard chrome plating with a 190 °C hydrogen-relief bake, or passivate/paint; vacuum-melted stock polishes to a fine mold finish and nitrides well.
Can 18Ni(350) Maraging Steel be formed, bent or molded?
Cold form, bend and deep-draw only in the solution-annealed state; hot work 1150–900 °C, then solution anneal at 815 °C before aging — aged parts are effectively non-formable.
What is the maximum service temperature of 18Ni(350) Maraging Steel?
18Ni(350) Maraging Steel is rated for continuous use to about 400°C (752 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 18Ni(350) Maraging Steel Aged and 18Ni(350) Maraging Steel-SA?
Aged is the default condition — standard delivered/final condition: peak ~2400 MPa strength with minimal distortion; pick when extreme static strength governs and toughness demands are moderate. SA: soft as-supplied/annealed condition for machining, cold forming and welding before final aging. Yield strength is 2,320 MPa in Aged versus 830 MPa in SA.
How much does 18Ni(350) Maraging Steel cost?
18Ni(350) Maraging Steel is a high-cost steel ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sources
- AMS 6515 — Steel bars, forgings, tubing 18Ni-12Co-5Mo (maraging 350) — SAE International (2017)
- ASTM A538/A538M — Pressure vessel plates, alloy steel, precipitation hardening (18Ni maraging Grades A/B/C) — ASTM (2018)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys (Maraging Steels) — ASM International (1990)
- ASM Handbook Vol.19 — Fatigue and Fracture — ASM International (1996)
- VascoMax C350 / Marval 18 maraging steel datasheet — Carpenter Technology / Aubert & Duval (2022)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.