Steel SKD61 · finish state
Steel SKD61 Nitrided
Properties of the Nitrided condition, compared with the other SKD61 tempers.
Surface treatment for extrusion dies and die-casting cores to resist erosion, soldering and abrasive wear; case is brittle so avoid sharp edges.
What is SKD61 Nitrided?
SKD61 Nitrided is SKD61 supplied in the Nitrided condition — surface treatment for extrusion dies and die-casting cores to resist erosion, soldering and abrasive wear; case is brittle so avoid sharp edges. SKD61 Nitrided has a yield strength of 415 MPa (60.2 ksi) and a tensile strength of 1,500 MPa (218 ksi) — weaker than 55% of steel grades. Elongation at break is 25% and the elastic modulus is 210 GPa (30.5 Msi). SKD61 Nitrided has a density of 7.8 g/cm³ (0.282 lb/in³), lighter than 87% of steel grades. It melts at 1,427°C (2,601 °F). Annealed is the default condition FabDigit quotes; Nitrided is available on request or by drawing note.
Advantages
- Polishes to a fine finish — 80/100, better than 97% of steel grades
- High service temperature — 560°C (1,040 °F), better than 96% of steel grades
- Good corrosion resistance — 30/100, better than 95% of steel grades
- Ductile — tolerates forming and impact — 25%, better than 76% of steel grades
Limitations
- Difficult to machine — 5/100, worse than 100% of steel grades
- High embodied carbon — 2.8 kg CO₂/kg, worse than 90% of steel grades
- Poor heat conductor — 24.5 W/m·K (14.2 BTU/hr·ft·°F), worse than 89% of steel grades
- Low electrical conductivity — 3.3 % IACS, worse than 87% of steel grades
SKD61 Nitrided properties
Typical room-temperature values for SKD61 Nitrided — 8 properties are specific to this condition; the rest are grade-level values shared by every SKD61 temper. Each bar shows where the value sits among the steel grades in FabDigit's library — further right is higher.
Physical2
SKD61 Nitrided has a density of 7.8 g/cm³ (0.282 lb/in³), lighter than 87% of steel grades. It melts at 1,427°C (2,601 °F).
Mechanical14
SKD61 Nitrided has a yield strength of 415 MPa (60.2 ksi) and a tensile strength of 1,500 MPa (218 ksi) — weaker than 55% of steel grades. Elongation at break is 25% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
SKD61 Nitrided is rated for continuous service to 560°C (1,040 °F). It conducts heat at 24.5 W/m·K (14.2 BTU/hr·ft·°F), worse than 89% of steel grades. Thermal expansion is 11 µm/m·K (6.11 µin/in·°F).
Electrical3
SKD61 Nitrided conducts electricity at 3.3 % IACS, worse than 87% of steel grades.
Chemical & Environmental3
Corrosion resistance is poor (30/100), better than 95% of steel grades.
Sustainability4
Producing a kilogram of SKD61 Nitrided takes about 36 MJ of energy and emits 2.8 kg of CO₂ — more than 88% of steel grades. Typical recycled content is 35%.
Manufacturability6
SKD61 Nitrided's machinability is not recommended (5/100, worse than 100% of steel grades); weldability fair (35/100); formability poor (30/100).
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other SKD61 tempers and conditions
SKD61 is also supplied in 6 other conditions. The full side-by-side table is on the SKD61 overview.
- AnnealedDefaultStandard as-delivered condition for plate, block and bar; machine the cavity first, then harden.415 MPa yield · 19 HRC
- Q&T 52-54 HRCUse only where wear/indentation resistance dominates and impact loading is low; toughness and thermal-fatigue life are reduced.1,650 MPa yield · 53 HRC
- NitridedSurface treatment for extrusion dies and die-casting cores to resist erosion, soldering and abrasive wear; case is brittle so avoid sharp edges.1,500 MPa tensile
- Hardened & TemperedHigher-hardness band for plastic moulds, shear blades and wear-critical hot-work tooling where thermal shock is moderate.1,470 MPa yield · 50 HRC
- ESRChoose remelted SKD61/H13 (e.g. Orvar Supreme, W302 ISO-B) for large die-casting dies needing isotropic toughness and mirror polish.1,270 MPa yield · 46 HRC
- Q&TToughness-biased hardness band for die-casting dies, extrusion tooling and hot-forging inserts exposed to thermal shock.1,250 MPa yield · 46 HRC
- Pre-hardened 38-42 HRCFor plastic-mould bases and holder blocks machined directly to final size without further heat treatment or distortion risk.1,050 MPa yield · 40 HRC
Working with SKD61 Nitrided
Is SKD61 easy to machine?
Machine in the annealed state with carbide tooling and rigid setups; above ~45 HRC switch to hard milling with coated carbide/CBN, grinding or EDM (recover the white layer by stress-relief temper).
Can SKD61 be welded?
Repair welding only — preheat/interpass 350–450 °C, matching 1.2344-type filler, slow cool then temper 20–30 °C below the last tempering temperature.
Can SKD61 be formed, bent or molded?
Hot work at 1050–850 °C followed by slow cool and soft anneal at 850–900 °C; no meaningful cold forming. Harden 1000–1030 °C, air/vacuum or oil quench, temper twice (≥550 °C) for the target hardness.
What surface finishes work on SKD61?
Takes a high mirror polish (best on ESR stock); protect with nitriding, hard chrome, or PVD CrN/AlTiN and always oil in storage since it is not corrosion resistant.
SKD61 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 |
|---|---|---|
| CJIS G4404 SKD61; ASTM H13 allows 0.32–0.45 | 0.35 – 0.42 | 0.39 |
| Si | 0.8 – 1.2 | 1 |
| Mn | 0.25 – 0.5 | 0.4 |
| P | ≤ 0.03 | — |
| S | ≤ 0.02 | — |
| Cr | 4.8 – 5.5 | 5.1 |
| Mo | 1 – 1.5 | 1.3 |
| V | 0.8 – 1.15 | 0.95 |
| Niresidual | ≤ 0.25 | — |
| Curesidual | ≤ 0.25 | — |
| Fe | balance | — |
SKD61 Nitrided — frequently asked
What is SKD61 Nitrided used for?
SKD61 Nitrided is typically used for aluminium and zinc die-casting dies, hot extrusion dies, mandrels and containers, hot forging die inserts, plastic injection mould cavities and cores, die-casting cores, ejector pins and sleeves and hot shear blades and hot punches. In short: workhorse hot-work tool.
What is the yield strength of SKD61 Nitrided?
SKD61 Nitrided has a typical yield strength of 415 MPa (60.2 ksi) and a tensile strength of 1,500 MPa (218 ksi) — weaker than 55% of steel grades. Strength varies by condition: see the 7 listed tempers.
Is SKD61 Nitrided easy to machine?
Not especially — machinability is rated not recommended (5/100, worse than 100% of steel grades). Machine in the annealed state with carbide tooling and rigid setups; above ~45 HRC switch to hard milling with coated carbide/CBN, grinding or EDM (recover the white layer by stress-relief temper).
Can SKD61 Nitrided be welded?
With care — weldability is rated fair (35/100). Repair welding only — preheat/interpass 350–450 °C, matching 1.2344-type filler, slow cool then temper 20–30 °C below the last tempering temperature.
What surface finishes work on SKD61 Nitrided?
Takes a high mirror polish (best on ESR stock); protect with nitriding, hard chrome, or PVD CrN/AlTiN and always oil in storage since it is not corrosion resistant.
Can SKD61 Nitrided be formed, bent or molded?
Hot work at 1050–850 °C followed by slow cool and soft anneal at 850–900 °C; no meaningful cold forming. Harden 1000–1030 °C, air/vacuum or oil quench, temper twice (≥550 °C) for the target hardness.
What is the maximum service temperature of SKD61 Nitrided?
SKD61 Nitrided is rated for continuous use to about 560°C (1,040 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between SKD61 Annealed and SKD61-ESR?
Annealed is the default condition — standard as-delivered condition for plate, block and bar; machine the cavity first, then harden. ESR: choose remelted SKD61/H13 (e.g. Orvar Supreme, W302 ISO-B) for large die-casting dies needing isotropic toughness and mirror polish. Yield strength is 415 MPa in Annealed versus 1,270 MPa in ESR.
Can FabDigit make parts in SKD61 Nitrided?
Yes — SKD61 Nitrided is available for CNC machining with instant online pricing. Upload a STEP file to get a price and a DFM check.
Sources
- JIS G 4404 Alloy tool steels (SKD61) — JSA (2015)
- ASTM A681 Standard Specification for Tool Steels Alloy (H13) — ASTM (2020)
- GB/T 1299 (4Cr5MoSiV1) — SAC (2014)
- ASM Handbook Vol. 1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- Uddeholm Orvar Supreme / Orvar 2 Microdized — Uddeholm (voestalpine) (2022)
- BÖHLER W302 / W302 ISOBLOC hot work tool steel — Böhler Edelstahl (2021)
- AISI H13 tool steel property record — MatWeb (2024)
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.