Steel Maraging 300
UNS K93120 · AISI/SAE 18Ni300 · ASTM A538 Grade C · EN 1.2709, 1.6358 · also Vascomax C-300
High-strength maraging grade (~2000 MPa yield) widely used in aerospace and additive manufacturing due to its excellent combination of strength, toughness, and simple age-hardening heat treatment without distortion.
Values for the Annealed condition
Maraging 300 tempers and conditions
Maraging 300 is supplied in 4 conditions, soft to hard. Annealed 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 |
|---|---|---|---|---|---|---|
AnnealedDefault solution annealed 815–830 °C, air cooled (soft martensite) | Standard supply condition of wrought bar/plate: soft enough to machine, form and weld before final aging. | 800 | 1,010 | 17 | 30 HRC | — |
post-build/post-weld stress relief (typ. 815 °C/1 h or 490 °C short cycle) | Use on AM or welded parts to remove residual stress and prevent distortion during machining, before final aging. | 950 | 1,100 | 14 | 33 HRC | 2.8 % IACS |
As PrintedDefault laser powder-bed fusion (MS1 / 1.2709 3DP), as-built | Pick for as-built LPBF parts before any heat treatment: already ~35 HRC, but with residual stress and slight anisotropy. | 1,000 | 1,130 | 12 | 35 HRC | 15 W/m·K |
Precipitation aged 480–500 °C / 3–6 h, air cooled | Final service condition: ~2000 MPa strength and 50–54 HRC with minimal distortion — choose for tooling, mold inserts and high-strength structural parts. | 1,900 | 1,950 | 7 | 52 HRC | 20 W/m·K |
What is Maraging 300?
High-strength maraging grade (~2000 MPa yield) widely used in aerospace and additive manufacturing due to its excellent combination of strength, toughness, and simple age-hardening heat treatment without distortion. Maraging 300 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). Maraging 300 has a yield strength of 800 MPa (116 ksi) and a tensile strength of 1,010 MPa (146 ksi) — stronger than 86% of steel grades. Elongation at break is 17% and the elastic modulus is 180 GPa (26.1 Msi).
What is Maraging 300 used for?
- Rocket motor cases and pressure shells
- Additively manufactured mold inserts with conformal cooling
- Die and punch tooling inserts
- Aerospace structural fittings and actuator parts
- High-torque drive shafts and couplings
- Motorsport and aerospace fasteners
- Extrusion and forming tool components
Advantages
- Polishes to a fine finish — 85/100, better than 99% of steel grades
- Good corrosion resistance — 25/100, better than 92% of steel grades
- High strength — 800 MPa (116 ksi), better than 86% of steel grades
- Readily welded — 80/100, better than 79% of steel grades
Limitations
- High embodied carbon — 6.5 kg CO₂/kg, worse than 98% of steel grades
- Low stiffness — 180 GPa (26.1 Msi), 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
- Low electrical conductivity — 2.9 % IACS, worse than 93% of steel grades
Maraging 300 properties
Typical room-temperature values for Maraging 300-Annealed; bars are the position among steel grades.
Physical3
Maraging 300 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).
Mechanical15
Maraging 300 has a yield strength of 800 MPa (116 ksi) and a tensile strength of 1,010 MPa (146 ksi) — stronger than 86% of steel grades. Elongation at break is 17% and the elastic modulus is 180 GPa (26.1 Msi).
Thermal6
Maraging 300 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 10.3 µm/m·K (5.72 µin/in·°F).
Electrical3
Maraging 300 conducts electricity at 2.9 % IACS, worse than 93% of steel grades.
Chemical & Environmental3
Corrosion resistance is poor (25/100), better than 92% of steel grades.
Sustainability4
Producing a kilogram of Maraging 300 takes about 100 MJ of energy and emits 6.5 kg of CO₂ — more than 99% of steel grades. Typical recycled content is 20%.
Manufacturability8
Maraging 300's machinability is fair (45/100, worse than 65% of steel grades); weldability very good (80/100); formability good (55/100).
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. Maraging 300 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with Maraging 300
Is Maraging 300 easy to machine?
Machine in the annealed/stress-relieved state with sharp carbide, rigid setups and generous coolant; aged 52 HRC material needs ceramic/CBN or grinding, and aging shrinks parts only ~0.05 %.
Can Maraging 300 be welded?
Excellent — TIG/laser/EB weld with matching filler, no preheat, low heat input and clean surfaces; re-age the weldment at 480–500 °C to restore joint strength.
Can Maraging 300 be formed, bent or molded?
Cold form, bend and deep draw only in the annealed condition (elongation ~17 %); hot work 900–1200 °C, then solution anneal — no cold forming after aging.
Manufacturability
The process limits FabDigit's quote engine applies to Maraging 300. Design inside these and the part quotes instantly; outside them it routes to an engineer.
CNC machining
| Machinability | Fair45 / 100 |
|---|---|
| ISO material group | P.2 |
| Cutting speed (rough / finish) | 180 / 210 m/min |
| Minimum wall | 0.8 mm |
| Minimum internal radius | 1 mm |
| Drill depth limit | 5× diameter |
| Best surface (machined / polished) | Ra 1.6 / — |
| Hardenable after machining | No |
Sheet metal
| Formability | Fair55 / 100 |
|---|---|
| Weldability | Better80 / 100 |
3D printing
| Technologies | DMLS |
|---|---|
| Layer height | 20 – 60 µmdefault 30 µm |
| Minimum wall / feature | 0.5 / 0.3 mm |
| Build envelope | 250 × 250 × 325 mm |
| Supports | Yes |
| Anisotropy | Mild |
| Mandatory post-processing | heat treatment |
Maraging 300 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 |
|---|---|---|
| Cultra-low carbon essential to toughness | ≤ 0.03 | 0.01 |
| Ni | 18 – 19 | 18.5 |
| Co | 8.5 – 9.5 | 9 |
| Moforms Ni3Mo precipitates | 4.6 – 5.2 | 4.9 |
| Ti | 0.5 – 0.8 | 0.65 |
| Al | 0.05 – 0.15 | 0.1 |
| Si | ≤ 0.1 | 0.05 |
| Mn | ≤ 0.1 | 0.05 |
| P | ≤ 0.01 | |
| S | ≤ 0.01 | |
| Fe | balance |
What surface finishes work on Maraging 300?
Takes a mirror polish (widely used for mold cavities) but is not stainless: protect with nitriding, hard chrome, electroless Ni, PVD or oil, and bake after any electroplating to avoid hydrogen embrittlement.
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).
Plating
CVD Coating
Black / Phosphate
Thermal Spray
Metal Finish
Equivalent designations
Standards and trade names that resolve to Steel Maraging 300 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- K93120
- AISI / SAE
- 18Ni300
- ASTM
- A538 Grade C
- EN / DIN / Werkstoff-Nr.
- 1.27091.6358X2NiCoMo18-9-5
- Trade names
- Vascomax C-300
How much does Maraging 300 cost?
Maraging 300 is a standard-cost steel ($$), cheaper than about 62% 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.
Maraging 300 — frequently asked
What is Maraging 300 used for?
Maraging 300 is typically used for rocket motor cases and pressure shells, additively manufactured mold inserts with conformal cooling, die and punch tooling inserts, aerospace structural fittings and actuator parts, high-torque drive shafts and couplings and motorsport and aerospace fasteners. In short: premium aerospace maraging bar.
What is the yield strength of Maraging 300?
Maraging 300 has a typical yield strength of 800 MPa (116 ksi) and a tensile strength of 1,010 MPa (146 ksi) — stronger than 86% of steel grades. Strength varies by condition: see the 4 listed tempers.
Is Maraging 300 easy to machine?
Reasonably — machinability is rated fair (45/100, worse than 65% of steel grades). Machine in the annealed/stress-relieved state with sharp carbide, rigid setups and generous coolant; aged 52 HRC material needs ceramic/CBN or grinding, and aging shrinks parts only ~0.05 %.
Can Maraging 300 be welded?
Yes — weldability is rated very good (80/100). Excellent — TIG/laser/EB weld with matching filler, no preheat, low heat input and clean surfaces; re-age the weldment at 480–500 °C to restore joint strength.
What surface finishes work on Maraging 300?
Takes a mirror polish (widely used for mold cavities) but is not stainless: protect with nitriding, hard chrome, electroless Ni, PVD or oil, and bake after any electroplating to avoid hydrogen embrittlement.
Can Maraging 300 be formed, bent or molded?
Cold form, bend and deep draw only in the annealed condition (elongation ~17 %); hot work 900–1200 °C, then solution anneal — no cold forming after aging.
What is the maximum service temperature of Maraging 300?
Maraging 300 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 Maraging 300 Annealed and Maraging 300 Aged?
Annealed is the default condition — standard supply condition of wrought bar/plate: soft enough to machine, form and weld before final aging. Aged: final service condition: ~2000 MPa strength and 50–54 HRC with minimal distortion — choose for tooling, mold inserts and high-strength structural parts. Yield strength is 800 MPa in Annealed versus 1,900 MPa in Aged.
How much does Maraging 300 cost?
Maraging 300 is a standard-cost steel ($$), cheaper than about 62% 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.
Can FabDigit make parts in Maraging 300?
Yes — Maraging 300 is available for CNC machining, sheet metal and 3D printing with instant online pricing. Upload a STEP file to get a price and a DFM check.
Sources
- ASM Specialty Handbook: Tool Materials / Maraging Steels — ASM International (1995)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels and High-Performance Alloys — ASM International (1990)
- AMS 6514 / ASTM A538 Grade C (18Ni-300 maraging steel) — SAE / ASTM (2019)
- DIN EN ISO 4957 / Werkstoff 1.2709 — DIN (2018)
- EOS MaragingSteel MS1 material data sheet — EOS GmbH (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.