Steel 18Ni(350) Maraging Steel-SA (Solution annealed)
Heat-treated state
UNS K93160 · AISI/SAE 18Ni350 · also Vascomax C350
Soft as-supplied/annealed condition for machining, cold forming and welding before final aging.
Values for the SA 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 |
|---|---|---|---|---|---|---|
SAThis page 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-SA?
18Ni(350) Maraging Steel-SA is 18Ni(350) Maraging Steel heat treated to SA — soft as-supplied/annealed condition for machining, cold forming and welding before final aging. 18Ni(350) Maraging Steel-SA has a yield strength of 830 MPa (120 ksi) and a tensile strength of 1,140 MPa (165 ksi) — stronger than 87% of steel grades. Elongation at break is 17% and the elastic modulus is 183 GPa (26.5 Msi). 18Ni(350) Maraging Steel-SA 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; SA is available on request or by drawing note.
Advantages
- Polishes to a fine finish — 80/100, better than 97% of steel grades
- Good corrosion resistance — 28/100, better than 94% of steel grades
- High strength — 830 MPa (120 ksi), better than 87% of steel grades
- Readily welded — 75/100, better than 76% of steel grades
Limitations
- High embodied carbon — 6.5 kg CO₂/kg, worse than 98% of steel grades
- Low fracture toughness — 38 MPa·√m (34.6 ksi·√in), worse than 93% of steel grades
- Poor heat conductor — 25 W/m·K (14.4 BTU/hr·ft·°F), worse than 88% of steel grades
- Low electrical conductivity — 3.8 % IACS, worse than 84% of steel grades
18Ni(350) Maraging Steel-SA properties
Typical room-temperature values for 18Ni(350) Maraging Steel-SA; 19 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-SA 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-SA has a yield strength of 830 MPa (120 ksi) and a tensile strength of 1,140 MPa (165 ksi) — stronger than 87% of steel grades. Elongation at break is 17% and the elastic modulus is 183 GPa (26.5 Msi).
Thermal6
18Ni(350) Maraging Steel-SA is rated for continuous service to 400°C (752 °F). It conducts heat at 25 W/m·K (14.4 BTU/hr·ft·°F), worse than 88% of steel grades. Thermal expansion is 11.3 µm/m·K (6.28 µin/in·°F).
Electrical3
18Ni(350) Maraging Steel-SA 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-SA 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-SA's machinability is fair (45/100, worse than 65% of steel grades); weldability very good (75/100); formability good (55/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 18Ni(350) Maraging Steel-SA
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-SA — frequently asked
What is 18Ni(350) Maraging Steel-SA used for?
18Ni(350) Maraging Steel-SA 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-SA?
18Ni(350) Maraging Steel-SA has a typical yield strength of 830 MPa (120 ksi) and a tensile strength of 1,140 MPa (165 ksi) — stronger than 87% of steel grades. Strength varies by condition: see the 4 listed tempers.
Is 18Ni(350) Maraging Steel-SA easy to machine?
Reasonably — machinability is rated fair (45/100, worse than 65% 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-SA be welded?
Yes — weldability is rated very good (75/100). 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-SA?
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-SA 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-SA?
18Ni(350) Maraging Steel-SA 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.
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.