Steel Maraging 300 Stress Relieved
Heat-treated state
UNS K93120 · AISI/SAE 18Ni300 · ASTM A538 Grade C · EN 1.2709, 1.6358 · also Vascomax C-300
Use on AM or welded parts to remove residual stress and prevent distortion during machining, before final aging.
Values for the Stress Relieved condition
Other Maraging 300 tempers and conditions
Maraging 300 is listed in 4 conditions; see the grade overview at Maraging 300.
- Annealed
- Stress Relieved
- As Printed
- Aged
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 | — |
Stress RelievedThis page 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 Stress Relieved?
Maraging 300 Stress Relieved is Maraging 300 heat treated to Stress Relieved — use on AM or welded parts to remove residual stress and prevent distortion during machining, before final aging. Maraging 300 Stress Relieved has a yield strength of 950 MPa (138 ksi) and a tensile strength of 1,100 MPa (160 ksi) — stronger than 91% of steel grades. Elongation at break is 14% and the elastic modulus is 175 GPa (25.4 Msi). Maraging 300 Stress Relieved 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). Annealed is the default condition FabDigit quotes; Stress Relieved is available on request or by drawing note.
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 — 950 MPa (138 ksi), better than 91% of steel grades
- Readily welded — 82/100, better than 81% of steel grades
Limitations
- Poor heat conductor — 17 W/m·K (9.82 BTU/hr·ft·°F), worse than 98% of steel grades
- High embodied carbon — 6.5 kg CO₂/kg, worse than 98% of steel grades
- Low stiffness — 175 GPa (25.4 Msi), worse than 96% of steel grades
- Low electrical conductivity — 2.8 % IACS, worse than 94% of steel grades
- Limited ductility — 14%, worse than 75% of steel grades
Maraging 300 Stress Relieved properties
Typical room-temperature values for Maraging 300 Stress Relieved; 22 are specific to this condition. Other listed values are Maraging 300 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
Maraging 300 Stress Relieved 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 Stress Relieved has a yield strength of 950 MPa (138 ksi) and a tensile strength of 1,100 MPa (160 ksi) — stronger than 91% of steel grades. Elongation at break is 14% and the elastic modulus is 175 GPa (25.4 Msi).
Thermal6
Maraging 300 Stress Relieved is rated for continuous service to 400°C (752 °F). It conducts heat at 17 W/m·K (9.82 BTU/hr·ft·°F), worse than 98% of steel grades. Thermal expansion is 10.3 µm/m·K (5.72 µin/in·°F).
Electrical3
Maraging 300 Stress Relieved conducts electricity at 2.8 % IACS, worse than 94% of steel grades.
Chemical & Environmental3
Corrosion resistance is poor (25/100), better than 92% of steel grades.
Sustainability4
Producing a kilogram of Maraging 300 Stress Relieved 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 Stress Relieved's machinability is fair (42/100, worse than 73% of steel grades); weldability very good (82/100); formability fair (50/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with Maraging 300 Stress Relieved
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.
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.
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 |
Maraging 300 Stress Relieved — frequently asked
What is Maraging 300 Stress Relieved used for?
Maraging 300 Stress Relieved 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 Stress Relieved?
Maraging 300 Stress Relieved has a typical yield strength of 950 MPa (138 ksi) and a tensile strength of 1,100 MPa (160 ksi) — stronger than 91% of steel grades. Strength varies by condition: see the 4 listed tempers.
Is Maraging 300 Stress Relieved easy to machine?
Not especially — machinability is rated fair (42/100, worse than 73% 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 Stress Relieved be welded?
Yes — weldability is rated very good (82/100). 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 Stress Relieved?
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 Stress Relieved 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 Stress Relieved?
Maraging 300 Stress Relieved 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.
Can FabDigit make parts in Maraging 300 Stress Relieved?
Yes — Maraging 300 Stress Relieved 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. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.