Steel 18Ni(190) VIM-VAR
Grade
also T-190, VascoMax 190
VIM-VAR = vacuum induction melted + vacuum arc remelted
Order this melt route for aerospace/critical rotating parts: lowest inclusion content, best transverse ductility and fracture toughness at the same nominal strength.
Values for the VIM-VAR condition
Other 18Ni(190) tempers and conditions
18Ni(190) is listed in 6 conditions; see the grade overview at 18Ni(190).
Compare all 6 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Annealed | Soft, tough nickel-martensite as supplied for machining, forming and welding before aging. | 800 | 1,000 | 18 | 29 HRC | 2.9 % IACS |
As-welded deposit | Condition of a weldment before the mandatory 480 °C re-age; strength is well below the aged parent and should not be used as a design basis. | 860 | 1,050 | 12 | 31 HRC | 3.1 % IACS |
Cold drawn | Cold-drawn bar and wire for tighter tolerance and better surface before aging; strain hardening also raises the final aged strength. | 1,030 | 1,170 | 10 | 34 HRC | 3 % IACS |
AgedDefault Solution annealed + aged 480 °C / 3–6 h, air cool | Standard delivered-strength condition: ~190 ksi UTS with the best toughness of the 18 % Ni maraging series and almost no distortion during aging. | 1,280 | 1,330 | 14 | 40 HRC | 3.8 % IACS |
VIM-VARThis page Vacuum induction melted + vacuum arc remelted | Order this melt route for aerospace/critical rotating parts: lowest inclusion content, best transverse ductility and fracture toughness at the same nominal strength. | 1,300 | 1,340 | 15 | 40 HRC | 3.8 % IACS |
Cold worked then aged 480 °C | Pick when extra strength is needed from thin bar, strip or wire; ductility and toughness drop relative to the plain aged condition. | 1,450 | 1,500 | 8 | 45 HRC | — |
What is 18Ni(190) VIM-VAR?
18Ni(190) VIM-VAR is 18Ni(190) in the VIM-VAR grade — order this melt route for aerospace/critical rotating parts: lowest inclusion content, best transverse ductility and fracture toughness at the same nominal strength. 18Ni(190) VIM-VAR has a yield strength of 1,300 MPa (189 ksi) and a tensile strength of 1,340 MPa (194 ksi) — stronger than 95% of steel grades. Elongation at break is 15% and the elastic modulus is 190 GPa (27.6 Msi). 18Ni(190) VIM-VAR has a density of 8 g/cm³ (0.289 lb/in³), heavier than 95% of steel grades. It melts at 1,413°C (2,575 °F). Aged is the default condition FabDigit quotes; VIM-VAR is available on request or by drawing note.
Advantages
- Tough — resists crack growth — 175 MPa·√m (159.3 ksi·√in), better than 98% of steel grades
- Polishes to a fine finish — 80/100, better than 97% of steel grades
- High strength — 1,300 MPa (189 ksi), better than 95% of steel grades
- Good corrosion resistance — 25/100, better than 92% of steel grades
- Readily welded — 90/100, better than 90% of steel grades
Limitations
- High embodied carbon — 4.6 kg CO₂/kg, worse than 96% of steel grades
- Poor heat conductor — 20.9 W/m·K (12.1 BTU/hr·ft·°F), worse than 95% of steel grades
- Low electrical conductivity — 3.8 % IACS, worse than 84% of steel grades
- Difficult to machine — 35/100, worse than 84% of steel grades
- Limited formability — 20/100, worse than 80% of steel grades
18Ni(190) VIM-VAR properties
Typical room-temperature values for 18Ni(190) VIM-VAR; 22 are specific to this condition. Other listed values are 18Ni(190) reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
18Ni(190) VIM-VAR has a density of 8 g/cm³ (0.289 lb/in³), heavier than 95% of steel grades. It melts at 1,413°C (2,575 °F).
Mechanical16
18Ni(190) VIM-VAR has a yield strength of 1,300 MPa (189 ksi) and a tensile strength of 1,340 MPa (194 ksi) — stronger than 95% of steel grades. Elongation at break is 15% and the elastic modulus is 190 GPa (27.6 Msi).
Thermal6
18Ni(190) VIM-VAR is rated for continuous service to 400°C (752 °F). It conducts heat at 20.9 W/m·K (12.1 BTU/hr·ft·°F), worse than 95% of steel grades. Thermal expansion is 10.1 µm/m·K (5.61 µin/in·°F).
Electrical3
18Ni(190) VIM-VAR conducts electricity at 3.8 % IACS, worse than 84% of steel grades.
Chemical & Environmental3
Corrosion resistance is poor (25/100), better than 92% of steel grades.
Sustainability4
Producing a kilogram of 18Ni(190) VIM-VAR takes about 55 MJ of energy and emits 4.6 kg of CO₂ — more than 94% of steel grades. Typical recycled content is 25%.
Manufacturability7
18Ni(190) VIM-VAR's machinability is fair (35/100, worse than 84% of steel grades); weldability excellent (90/100); formability poor (20/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 18Ni(190) VIM-VAR
Is 18Ni(190) easy to machine?
Rough machine in the annealed condition (~30 HRC) with sharp carbide tools, rigid setups and generous coolant; finish after aging where only ~0.05 % growth occurs, using slow, positive-rake cuts.
Can 18Ni(190) be welded?
Excellent GTAW/EBW/laser weldability with matching filler, no preheat and low heat input; keep the joint clean and re-age at 480 °C after welding to restore strength.
Can 18Ni(190) be formed, bent or molded?
Form, bend, deep-draw or cold-draw only in the solution-annealed state; hot work 1150–900 °C, then re-anneal at 815 °C before aging.
What surface finishes work on 18Ni(190)?
No anodizing; protect with cadmium, nickel or electroless-nickel plating, phosphate or paint, and bake after any plating/pickling to avoid hydrogen embrittlement — nitriding gives a hard 65+ HRC case during aging.
18Ni(190) 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 |
|---|---|---|
| Ckept very low; carbon degrades toughness | ≤ 0.03 | 0.02 |
| Ni | 17 – 19 | 18 |
| Copromotes Mo precipitation | 8 – 9 | 8.5 |
| MoNi3Mo / Fe2Mo aging precipitates | 2.8 – 3.4 | 3.1 |
| Tilower Ti than 250/300 grades — sets the 190 ksi level | 0.1 – 0.25 | 0.18 |
| Al | 0.05 – 0.15 | 0.1 |
| Si | ≤ 0.1 | 0.05 |
| Mn | ≤ 0.1 | 0.05 |
| S | ≤ 0.01 | 0 |
| P | ≤ 0.01 | 0.01 |
| Bgrain-boundary addition, optional | ≤ 0 | 0 |
| Zroptional | ≤ 0.02 | 0.01 |
| Caoptional deoxidizer | ≤ 0.05 | 0.02 |
| Fe | balance | — |
18Ni(190) VIM-VAR — frequently asked
What is 18Ni(190) VIM-VAR used for?
18Ni(190) VIM-VAR is typically used for fracture-critical aerospace fittings, tooling requiring high toughness, pressure vessel components and rocket motor cases (lower-load variants). In short: toughest 18Ni maraging grade; weldable ultra-high-strength steel; near-zero ageing distortion.
What is the yield strength of 18Ni(190) VIM-VAR?
18Ni(190) VIM-VAR has a typical yield strength of 1,300 MPa (189 ksi) and a tensile strength of 1,340 MPa (194 ksi) — stronger than 95% of steel grades. Strength varies by condition: see the 6 listed tempers.
Is 18Ni(190) VIM-VAR easy to machine?
Not especially — machinability is rated fair (35/100, worse than 84% of steel grades). Rough machine in the annealed condition (~30 HRC) with sharp carbide tools, rigid setups and generous coolant; finish after aging where only ~0.05 % growth occurs, using slow, positive-rake cuts.
Can 18Ni(190) VIM-VAR be welded?
Yes — weldability is rated excellent (90/100). Excellent GTAW/EBW/laser weldability with matching filler, no preheat and low heat input; keep the joint clean and re-age at 480 °C after welding to restore strength.
What surface finishes work on 18Ni(190) VIM-VAR?
No anodizing; protect with cadmium, nickel or electroless-nickel plating, phosphate or paint, and bake after any plating/pickling to avoid hydrogen embrittlement — nitriding gives a hard 65+ HRC case during aging.
Can 18Ni(190) VIM-VAR be formed, bent or molded?
Form, bend, deep-draw or cold-draw only in the solution-annealed state; hot work 1150–900 °C, then re-anneal at 815 °C before aging.
What is the maximum service temperature of 18Ni(190) VIM-VAR?
18Ni(190) VIM-VAR 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(190) Aged and 18Ni(190)-ANN?
Aged is the default condition — standard delivered-strength condition: ~190 ksi UTS with the best toughness of the 18 % Ni maraging series and almost no distortion during aging. ANN: soft, tough nickel-martensite as supplied for machining, forming and welding before aging. Yield strength is 1,280 MPa in Aged versus 800 MPa in ANN.
Sources
- ASTM A538/A538M — Pressure Vessel Plates, Alloy Steel, Precipitation Hardening (Maraging), 18 % Nickel — ASTM International (2019)
- AMS 6512 / AMS 6520 — 18Ni maraging steel bar, plate and sheet — SAE International (2018)
- ASM Handbook Vol.1, Properties and Selection: Irons, Steels and High-Performance Alloys — Maraging Steels — ASM International (1990)
- ASM Specialty Handbook: Carbon and Alloy Steels — ASM International (1996)
- VascoMax / Marval 18 Ni maraging steel technical data — Carpenter / Aubert & Duval (2020)
- MMPDS-17 maraging steel design allowables (18Ni series) — Battelle (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.