Steel 718H · finish state
Steel 718H Nitrided
Properties of the Nitrided condition, compared with the other 718H tempers.
Pick for glass-filled or abrasive resins and for wear faces where core toughness must stay unchanged.
What is 718H Nitrided?
718H Nitrided is 718H supplied in the Nitrided condition — pick for glass-filled or abrasive resins and for wear faces where core toughness must stay unchanged. 718H Nitrided has a yield strength of 900 MPa (131 ksi) and a tensile strength of 1,080 MPa (157 ksi) — stronger than 90% of steel grades. Elongation at break is 13% and the elastic modulus is 205 GPa (29.7 Msi). 718H Nitrided has a density of 7.8 g/cm³ (0.282 lb/in³), lighter than 87% of steel grades. It melts at 1,420°C (2,588 °F). Prehard is the default condition FabDigit quotes; Nitrided is available on request or by drawing note.
Advantages
- Good corrosion resistance — 25/100, better than 91% of steel grades
- High strength — 900 MPa (131 ksi), better than 90% of steel grades
- High service temperature — 450°C (842 °F), better than 86% of steel grades
Limitations
- Difficult to machine — 15/100, worse than 98% of steel grades
- Limited formability — 10/100, worse than 94% of steel grades
- Poor heat conductor — 33 W/m·K (19.1 BTU/hr·ft·°F), worse than 80% of steel grades
- Limited ductility — 13%, worse than 78% of steel grades
718H Nitrided properties
Typical room-temperature values for 718H Nitrided — 8 properties are specific to this condition; the rest are grade-level values shared by every 718H temper. Each bar shows where the value sits among the steel grades in FabDigit's library — further right is higher.
Physical3
718H Nitrided has a density of 7.8 g/cm³ (0.282 lb/in³), lighter than 87% of steel grades. It melts at 1,420°C (2,588 °F).
Mechanical15
718H Nitrided has a yield strength of 900 MPa (131 ksi) and a tensile strength of 1,080 MPa (157 ksi) — stronger than 90% of steel grades. Elongation at break is 13% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
718H Nitrided is rated for continuous service to 450°C (842 °F). It conducts heat at 33 W/m·K (19.1 BTU/hr·ft·°F), worse than 80% of steel grades. Thermal expansion is 12.5 µm/m·K (6.94 µin/in·°F).
Electrical2
718H Nitrided has an electrical resistivity of 2.2×10⁻⁷ Ω·m.
Chemical & Environmental2
Corrosion resistance is poor (25/100), better than 91% of steel grades.
Sustainability4
Producing a kilogram of 718H Nitrided takes about 34 MJ of energy and emits 2.3 kg of CO₂ — more than 82% of steel grades. Typical recycled content is 35%.
Manufacturability6
718H Nitrided's machinability is poor (15/100, worse than 98% of steel grades); weldability fair (40/100); formability not recommended (10/100).
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other 718H tempers and conditions
718H is also supplied in 2 other conditions. The full side-by-side table is on the 718H overview.
- PrehardDefaultDefault stock condition: machine cavities and mould bases directly, no heat treatment or distortion afterwards.900 MPa yield · 32 HRC
- NitridedPick for glass-filled or abrasive resins and for wear faces where core toughness must stay unchanged.1,080 MPa tensile
- AnnealedChoose when the block will be rough-machined soft and then through-hardened/tempered in-house or after weld repair.480 MPa yield · 220 HB
Working with 718H Nitrided
Is 718H easy to machine?
Machines predictably at ~28–34 HRC with coated carbide (P20-type data, ~60 % of AISI 1212); use rigid setups and stress-relieve at 550 °C after heavy roughing to avoid cavity movement.
Can 718H be welded?
Weldable only with 250–325 °C preheat, Ni-alloyed mould-repair filler and slow post-weld temper 25–50 °C below the original tempering temperature; hydrogen control is essential.
Can 718H be formed, bent or molded?
Supplied prehardened for machining, not for cold forming; hot working 1100–850 °C followed by slow cooling and annealing if reforged.
What surface finishes work on 718H?
Takes fine EDM texturing and mirror polish (low-S/vacuum-degassed melts best); protect with hard chrome, electroless nickel or nitriding for corrosive resins and long-term storage.
718H 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 |
|---|---|---|
| C | 0.35 – 0.42 | 0.38 |
| Si | 0.2 – 0.4 | 0.3 |
| Mn | 1.3 – 1.6 | 1.45 |
| Cr | 1.8 – 2.1 | 1.95 |
| Mo | 0.15 – 0.25 | 0.2 |
| NiNi addition gives uniform through-hardness in thick plate | 0.9 – 1.2 | 1.05 |
| P | ≤ 0.03 | — |
| Smax; low-S for polishing grades | ≤ 0.03 | — |
| Fe | balance | — |
718H Nitrided — frequently asked
What is 718H Nitrided used for?
718H Nitrided is typically used for injection mould cavities and cores, mould inserts, large mould bases and bolsters, blow mould bodies, die-cast trim and holder blocks and structural foam and thick-wall tooling. In short: standard prehard mold steel.
What is the yield strength of 718H Nitrided?
718H Nitrided has a typical yield strength of 900 MPa (131 ksi) and a tensile strength of 1,080 MPa (157 ksi) — stronger than 90% of steel grades. Strength varies by condition: see the 3 listed tempers.
Is 718H Nitrided easy to machine?
Not especially — machinability is rated poor (15/100, worse than 98% of steel grades). Machines predictably at ~28–34 HRC with coated carbide (P20-type data, ~60 % of AISI 1212); use rigid setups and stress-relieve at 550 °C after heavy roughing to avoid cavity movement.
Can 718H Nitrided be welded?
With care — weldability is rated fair (40/100). Weldable only with 250–325 °C preheat, Ni-alloyed mould-repair filler and slow post-weld temper 25–50 °C below the original tempering temperature; hydrogen control is essential.
What surface finishes work on 718H Nitrided?
Takes fine EDM texturing and mirror polish (low-S/vacuum-degassed melts best); protect with hard chrome, electroless nickel or nitriding for corrosive resins and long-term storage.
Can 718H Nitrided be formed, bent or molded?
Supplied prehardened for machining, not for cold forming; hot working 1100–850 °C followed by slow cooling and annealing if reforged.
What is the maximum service temperature of 718H Nitrided?
718H Nitrided is rated for continuous use to about 450°C (842 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Can FabDigit make parts in 718H Nitrided?
Yes — 718H Nitrided is available for CNC machining with instant online pricing. Upload a STEP file to get a price and a DFM check.
Sources
- DIN EN ISO 4957 — Tool steels (1.2738 / 40CrMnNiMo8-6-4) — ISO/DIN (2018)
- Prehardened P20+Ni mould steel plate datasheets (718/718H class) — Mould steel producers (2023)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels — ASM International (1990)
- ASM Handbook Vol.19 — Fatigue and Fracture — ASM International (1996)
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.