Why is maraging steel so good for 3D-printed molds?

It prints well, machines in the soft solution-annealed state, and then ages at only ~490 °C with near-zero distortion — conformal cooling channels keep their designed shape.

No. Despite 18% nickel it has almost no chromium, so it rusts like a plain steel and needs the same corrosion care as other tool steels.

Grades · Tool Steel · 1.2709 Maraging / X3NiCoMoTi18-9-5

1.2709 Maraging / X3NiCoMoTi18-9-5

Data verified

1.2709 is an 18% nickel maraging steel — the grade behind most metal 3D-printing (LPBF) tooling and high-end die inserts. With almost no carbon, it hardens not by quenching but by precipitating intermetallics during a low-temperature age, reaching ~2000 MPa with toughness no quenched steel can match at that strength.

DIN1.2709

AISIMaraging 300 (C300 type)

CategoryTool Steel

Chemical composition

Element	Content (%)
C	≤0.03
Si	≤0.10
Mn	≤0.10
P	≤0.008
S	≤0.008
Ni	17.00–19.00
Co	8.50–9.50
Mo	4.60–5.20
Ti	0.50–0.80
Al	0.05–0.15

Weight percent, per the governing standard ranges. Actual values per heat are on the mill certificate.

Properties

Delivery condition	Solution annealed, soft (~30 HRC)
Aged hardness	50–54 HRC
Tensile strength (aged)	1900–2100 MPa
Density	8.00 g/cm³

Heat treatment

Solution anneal 820–840 °C (soft and machinable), machine, then age 480–510 °C for ~3–6 h. Aging shrinks the part only ~0.1% and uniformly, so finished dimensions survive the hardening step.

Equivalent grades

Standard	Designation
din	1.2709
aisi	Maraging 300 (C300 type)

Equivalents overlap in chemistry and use but are not always identical — see our equivalents guide before substituting in certified designs.

Applications & Processing

Applications: Conformal-cooled injection mold inserts (the standard LPBF tooling powder), die casting dies, aerospace and motorsport structural parts, high-strength tooling.

Processing: Machine it soft, age it hard — the workflow is the reverse of conventional tool steel. Weld repair with matching maraging filler is routine; powder form (15–45 µm) is a major supply channel for additive manufacturing.

FAQ

Why is maraging steel so good for 3D-printed molds?: It prints well, machines in the soft solution-annealed state, and then ages at only ~490 °C with near-zero distortion — conformal cooling channels keep their designed shape.
Is 1.2709 stainless?: No. Despite 18% nickel it has almost no chromium, so it rusts like a plain steel and needs the same corrosion care as other tool steels.

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Source: EN / SEW and mill published ranges · Last updated 2026-11-03. Data is indicative — verify critical values against the governing standard and mill certificate before use.