Steel 18Ni(350) Maraging Steel AGED-OA
Precip hard
UNS K93160 · AISI/SAE 18Ni350 · also Vascomax C350
AGED-OA = overaged / toughness-optimized age
Slightly overaged cycle trading ~150–250 MPa of strength for better ductility and K_IC in fracture-critical parts.
Values for the AGED-OA condition
Other 18Ni(350) Maraging Steel tempers and conditions
18Ni(350) Maraging Steel is listed in 4 conditions; see the grade overview at 18Ni(350) Maraging Steel.
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 |
AGED-OAThis page 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 AGED-OA?
18Ni(350) Maraging Steel AGED-OA is 18Ni(350) Maraging Steel in the AGED-OA condition — slightly overaged cycle trading ~150–250 MPa of strength for better ductility and K_IC in fracture-critical parts. 18Ni(350) Maraging Steel AGED-OA has a yield strength of 2,100 MPa (305 ksi) and a tensile strength of 2,200 MPa (319 ksi) — stronger than 100% of steel grades. Elongation at break is 9% and the elastic modulus is 190 GPa (27.6 Msi). 18Ni(350) Maraging Steel AGED-OA 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). Aged is the default condition FabDigit quotes; AGED-OA is available on request or by drawing note.
Advantages
- High strength — 2,100 MPa (305 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
- Poor heat conductor — 20 W/m·K (11.6 BTU/hr·ft·°F), worse than 96% of steel grades
- Limited formability — 10/100, worse than 95% of steel grades
- Limited ductility — 9%, worse than 93% of steel grades
- Difficult to machine — 25/100, worse than 93% of steel grades
18Ni(350) Maraging Steel AGED-OA properties
Typical room-temperature values for 18Ni(350) Maraging Steel AGED-OA; 23 are specific to this condition. Other listed values are 18Ni(350) Maraging Steel reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
18Ni(350) Maraging Steel AGED-OA 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 AGED-OA has a yield strength of 2,100 MPa (305 ksi) and a tensile strength of 2,200 MPa (319 ksi) — stronger than 100% of steel grades. Elongation at break is 9% and the elastic modulus is 190 GPa (27.6 Msi).
Thermal6
18Ni(350) Maraging Steel AGED-OA is rated for continuous service to 425°C (797 °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 AGED-OA conducts electricity at 3.9 % IACS, worse than 83% 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 AGED-OA 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 AGED-OA's machinability is poor (25/100, worse than 93% of steel grades); weldability very good (70/100); formability not recommended (10/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 18Ni(350) Maraging Steel AGED-OA
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.
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.
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 | — |
18Ni(350) Maraging Steel AGED-OA — frequently asked
What is 18Ni(350) Maraging Steel AGED-OA used for?
18Ni(350) Maraging Steel AGED-OA 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 AGED-OA?
18Ni(350) Maraging Steel AGED-OA has a typical yield strength of 2,100 MPa (305 ksi) and a tensile strength of 2,200 MPa (319 ksi) — stronger than 100% of steel grades. Strength varies by condition: see the 4 listed tempers.
Is 18Ni(350) Maraging Steel AGED-OA easy to machine?
Not especially — machinability is rated poor (25/100, worse than 93% 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 AGED-OA be welded?
Yes — weldability is rated very good (70/100). 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 AGED-OA?
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 AGED-OA 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 AGED-OA?
18Ni(350) Maraging Steel AGED-OA is rated for continuous use to about 425°C (797 °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.
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. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.