Printed from Kezuriba (kezuriba.net/en/materials/maraging300/)
18Ni maraging 300
ISO P (steel)Maraging steel (Co-strengthened 18Ni). Grade 250 is UNS K92890. Number: UNS K93120. Standard: AMS 6514 (bar and forgings), MIL-S-46850. Grade 250 is AMS 6512. ASTM A579/A579M (Grades 71–75 are maraging steels) was withdrawn in 2024.
🌐JIS and international equivalents
“Close” means composition or properties are not exactly the same. Before substituting, check the values in each standard.
| System | Designation | Number | Relation | Confidence |
|---|---|---|---|---|
| UNS | 18Ni maraging 300 | UNS K93120 | — | |
| JIS | — | — | Not confirmed | |
| DIN/EN (aerospace WL) | WL 1.6354approx. 0.01C-18Ni-9Co-5Mo-0.7Ti, bar and forgings | 1.6354 | close | Agrees in 2+ sources[2][8][7] |
| GB | — | — | Not confirmed |
Differences between the equivalents (from the sources)
- JIS : No maraging steel grade was found in JIS. In Japan it is sold under tool steel manufacturers' trade names, but trade names are not used as designations
- DIN/EN (aerospace WL) WL 1.6354: Böhler V300 shows the material number 1.6354 (SEL). DIN Media has a page for the aerospace material standard WL 1.6354 (1981-03), and the nominal composition in its title is close to grade 300. The EN designation X2NiCoMoTi18-9-5 was seen only in powder maker materials for additive manufacturing and has not been confirmed in primary sources. For grade 250, Böhler V250 shows 1.6359 / X2NiCoMo18-8-5 (EN) (one company only)
- GB : No corresponding Chinese designation was found in primary sources
📄Related specifications (AMS, ASTM etc.)
Specifications called up on purchase orders and drawings. AMS are SAE aerospace material specifications, split by product form (bar, plate, forging), melting practice and heat treatment. Standard texts are paid, so only titles and scopes checked on the publishers’ public pages are shown.
| Spec | Scope | Confidence |
|---|---|---|
| AMS 6514 | Steel, Maraging, Bars, Forgings, Mechanical Tubing, Rings, and Forging Stock, 18.5Ni - 9.0Co - 4.9Mo - 0.65Ti - 0.10Al (Maraging 300), Premium Aircraft Quality, Consumable Electrode Vacuum Remelted, AnnealedGrade 300 bar, forgings, tube and rings (up to 254 mm in diameter). Aerospace premium quality, vacuum consumable electrode remelted, delivered in the annealed (solution annealed) condition. Revision letter L confirmed on SAE Mobilus | Agrees in 2+ sources[9] |
| AMS 6512 | Steel, Maraging, Bars, Forgings, Mechanical Tubing, Rings, and Forging Stock 18Ni - 7.8Co - 4.9Mo - 0.40Ti - 0.10Al Consumable Electrode Vacuum Melted, AnnealedGrade 250 bar, forgings, tube and rings (up to 254 mm in diameter). Aerospace premium quality, consumable electrode vacuum melted, annealed condition. Revision letter J confirmed | Agrees in 2+ sources[10] |
| AMS 6521 | Steel Sheet, Strip, and Plate, Maraging, 18.5Ni - 9.0Co - 4.9Mo - 0.65Ti - 0.10Al, Consumable Electrode Melted, Solution Heat TreatedGrade 300 sheet, strip and plate, solution annealed condition. The SAE Mobilus page for revision C states "Cancelled September 2005" (withdrawn). Carpenter still lists it as a corresponding standard for NiMark 250 | One source / reference[11] |
| ASTM A579/A579M | Standard Specification for Superstrength Alloy Steel Forgings (Withdrawn 2024)Forgings for high-stress structural members with yield strength over 965 MPa. Maraging steels are Grades 71–75. A579/A579M-20 was the last edition and it was withdrawn in 2024 | Agrees in 2+ sources[12] |
| MIL-S-46850 | US military maraging steel specification. Liberty cites revision D (MIL-S-46850D), and Carpenter lists it as a corresponding standard for NiMark 250 and 300. Its current validity and title could not be confirmed on government public pages | One source / reference[3][1] |
All ASTM standards on Kezuriba: ASTM standards quick reference.
✈Main aerospace uses (as stated in the sources)
- Missile and rocket motor cases, wind tunnel models, actuators, landing gear parts, high-performance shafts, gears and fasteners (ATI)[6]
- Missiles and launch equipment, slat tracks and drive shafts (Liberty)[3]
- High-stress parts in the aircraft and rocket industries. Parts that are through-hardened without quenching and may be welded during fabrication (Böhler V300 and V250)[2][7]
⚗Chemical composition (mass %)
Ranges differ between specifications, so each one has its own column (dark figures agree in several sources, light figures come from one source).
| Element | Spec ① | Spec ② |
|---|---|---|
| C | ≤ 0.03[2][3] | — |
| Si | ≤ 0.1[2][3] | — |
| Mn | ≤ 0.1[2][3] | — |
| P | ≤ 0.01[2][3] | — |
| S | ≤ 0.01[2][3] | — |
| Ni | 18 – 19[2][3] | 17 – 19[7] |
| Co | 8.5 – 9.5[2][3] | 7.0 – 8.5[7] |
| Mo | 4.6 – 5.2[2][3] | 4.6 – 5.2[7] |
| Ti | 0.5 – 0.8[2][3] | 0.3 – 0.6[7] |
| Al | 0.05 – 0.15[2][3] | 0.05 – 0.15[7] |
| Cr | ≤ 0.5[2] | — |
| Cu | ≤ 0.5[2] | — |
| B | ≤ 0.004[2] | — |
| Ca | ≤ 0.05[2] | — |
| Zr | ≤ 0.02[2] | — |
- Spec ① Related to AMS 6514 (Böhler V300 table) and MIL-S-46850D (Liberty table). Both sources give the same value
- Spec ② Related to BS S 162 (Böhler V250 table). The range in AMS 6512 has not been confirmed
⚖Density
8 g/cm³
One source / reference[6]
ATI gives 0.289 lb/in³ (8.0 g/cc) for both C-250 and C-300. Not confirmed in a second manufacturer's material
Calculate weight in 18Ni maraging 300 →💪Mechanical properties
“Reference” values are not specified minimums from the standard but figures published by makers and others.
| Condition | Tensile MPa | Yield MPa | Elong. % | Hardness | Type of value |
|---|---|---|---|---|---|
| Solution annealed (as-delivered condition) | 1034 | 758 | 18 | HRC 32 | Typical value (ATI C-300 Nominal Annealed Properties; 150 ksi / 110 ksi converted to MPa) One source / reference[6] |
| Solution annealed plus aged | ≥ 1931 | — | ≥ 5 | HRC 52 min | Specified value (listed by Liberty as the limit for Maraging 300 in MIL-S-46850D; tensile strength 280,000 psi min converted to MPa) One source / reference[3] |
| Solution annealed plus aged (material covered by AMS 6514) | — | ≥ 1862 | — | — | Value assumed by the standard (Böhler V300 product description: it has been used for parts that are through-hardened without quenching to a minimum yield strength of 270 ksi (1862 MPa)). Carpenter also states a yield strength above 270 ksi when aged at 482°C One source / reference[2][1] |
| Solution annealed plus aged (small-diameter bar) | 2027 | 2000 | 11 | HRC 50–55 | Typical value (ATI C-300 Figure 1; 294,000 / 290,000 psi converted. Charpy V-notch is 17 ft-lb (about 23 J); not converted to J/cm² because the test piece cross-section is not given) One source / reference[6] |
| Solution annealed plus aged (small-diameter bar) | 1793 | 1758 | 11 | HRC 48–52 | Typical value (ATI C-250 Figure 1; 260,000 / 255,000 psi converted. Charpy 20 ft-lb). Böhler V250 is described as having been used for parts with a minimum yield strength of 247 ksi (1700 MPa) One source / reference[6][7] |
1 MPa ≈ 145 psi (0.145 ksi). Hardness conversion · unit converter
🔧Machinability notes (as stated in the sources)
- The solution annealed as-delivered condition is tough and relatively soft (stated as HRC 28–32 / 30–35), so it is easy to machine and form. After machining it is hardened by a low-temperature aging treatment. No protective atmosphere is needed, and the dimensional change on aging is uniform in all directions and predictable (ATI)[6]
- Easy to machine before aging (Liberty; supplied as solution annealed bar for machining)[3]
📚Sources
Primary sources (public documents from makers, industry associations and standards bodies), numbered where each value is cited. Many are in Japanese.
- carpentertechnology.com https://www.carpentertechnology.com/alloy-finder/nimark-300-m300
- bohler-edelstahl.com https://www.bohler-edelstahl.com/app/uploads/sites/248/productdb/api/v300_en_gb.pdf
- libertysteelgroup.com https://libertysteelgroup.com/uk/wp-content/uploads/sites/2/2021/01/Aerospace-Maraging-300…
- carpentertechnology.com https://www.carpentertechnology.com/alloy-finder/nimark-250
- sandvik.coromant.com https://www.sandvik.coromant.com/en-us/knowledge/materials/workpiece-materials
- atimaterials.com https://atimaterials.com/Products/Documents/datasheets/stainless-specialty-steel/specialty…
- bohler-edelstahl.com https://www.bohler-edelstahl.com/app/uploads/sites/248/productdb/api/v250_en_gb.pdf
- dinmedia.de https://www.dinmedia.de/en/standard/wl-1-6354/900038
- saemobilus.sae.org https://saemobilus.sae.org/content/ams6514l/
- saemobilus.sae.org https://saemobilus.sae.org/content/ams6512j/
- saemobilus.sae.org https://saemobilus.sae.org/content/ams6521c/
- store.astm.org https://store.astm.org/a0579_a0579m-20.html
Other materials
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