Steel H21 Nitrided
Finish state
AISI/SAE H21 · UNS T20821 · EN 1.2581 · GB 3Cr2W8V
Surface treatment applied to finished dies to raise wear and washout resistance; core properties as Q&T.
Values for the Nitrided condition
Other H21 tempers and conditions
H21 is listed in 7 conditions; see the grade overview at H21.
Compare all 7 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
AnnealedDefault soft-annealed, as-supplied bar/plate | Standard stock condition for machining dies and inserts before hardening. | 620 | 900 | 18 | 19 HRC | 3.1 % IACS |
Hot Rolled / As-forged (unannealed) | Mill condition of large forged blocks before soft annealing; only for re-heat-treatment, not for machining. | 850 | 1,100 | 10 | 34 HRC | 27 W/m·K |
High-temper condition for maximum toughness | Pick for large hot-forging dies and dummy blocks where gross cracking, not wear, is the failure mode. | 1,100 | 1,300 | 12 | 40 HRC | 28 W/m·K |
Balanced hot-work die hardness | Most common working hardness for hot extrusion dies, punches and brass die-casting inserts. | 1,350 | 1,600 | 9 | 46 HRC | 28 W/m·K |
Quenched and tempered | General hardened-and-tempered service condition for hot dies at 45–52 HRC. | 1,450 | 1,700 | 8 | 49 HRC | — |
NitridedThis page hardened, tempered and gas/plasma nitrided surface | Surface treatment applied to finished dies to raise wear and washout resistance; core properties as Q&T. | 1,450 | 1,700 | 7 | 49 HRC | 28 W/m·K |
High hardness for maximum hot wear resistance | Choose for hot shear blades and small punches where abrasive hot wear dominates and shock is low. | 1,600 | 1,850 | 5 | 52 HRC | 28 W/m·K |
What is H21 Nitrided?
H21 Nitrided is H21 supplied in the Nitrided condition — surface treatment applied to finished dies to raise wear and washout resistance; core properties as Q&T. H21 Nitrided has a yield strength of 1,450 MPa (210 ksi) and a tensile strength of 1,700 MPa (247 ksi) — stronger than 97% of steel grades. Elongation at break is 7% and the elastic modulus is 208 GPa (30.2 Msi). H21 Nitrided has a density of 8.28 g/cm³ (0.299 lb/in³), heavier than 98% of steel grades. It melts at 1,420°C (2,588 °F). Annealed is the default condition FabDigit quotes; Nitrided is available on request or by drawing note.
Advantages
- High service temperature — 600°C (1,112 °F), better than 98% of steel grades
- High strength — 1,450 MPa (210 ksi), better than 97% of steel grades
- Good corrosion resistance — 30/100, better than 95% of steel grades
- Polishes to a fine finish — 65/100, better than 78% of steel grades
Limitations
- Difficult to machine — 5/100, worse than 100% of steel grades
- Difficult to weld — 5/100, worse than 100% of steel grades
- Limited formability — 1/100, worse than 100% of steel grades
- Low fracture toughness — 22 MPa·√m (20 ksi·√in), worse than 98% of steel grades
- Limited ductility — 7%, worse than 96% of steel grades
H21 Nitrided properties
Typical room-temperature values for H21 Nitrided; 20 are specific to this condition. Other listed values are H21 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
H21 Nitrided has a density of 8.28 g/cm³ (0.299 lb/in³), heavier than 98% of steel grades. It melts at 1,420°C (2,588 °F).
Mechanical17
H21 Nitrided has a yield strength of 1,450 MPa (210 ksi) and a tensile strength of 1,700 MPa (247 ksi) — stronger than 97% of steel grades. Elongation at break is 7% and the elastic modulus is 208 GPa (30.2 Msi).
Thermal6
H21 Nitrided is rated for continuous service to 600°C (1,112 °F). It conducts heat at 28 W/m·K (16.2 BTU/hr·ft·°F), worse than 85% of steel grades. Thermal expansion is 11.8 µm/m·K (6.56 µin/in·°F).
Electrical3
H21 Nitrided conducts electricity at 3.1 % IACS, worse than 89% of steel grades.
Chemical & Environmental2
Corrosion resistance is poor (30/100), better than 95% of steel grades.
Sustainability4
Producing a kilogram of H21 Nitrided takes about 42 MJ of energy and emits 3 kg of CO₂ — more than 92% of steel grades. Typical recycled content is 45%.
Manufacturability8
H21 Nitrided's machinability is not recommended (5/100, worse than 100% of steel grades); weldability not recommended (5/100); formability not recommended (1/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with H21 Nitrided
Is H21 easy to machine?
Machine only in the annealed condition (≤241 HB) with rigid setups and coated carbide; tungsten carbides are abrasive so keep speeds moderate, and finish-grind after hardening.
Can H21 be welded?
Repair welding only: preheat 400–500 °C, matching W-alloy or H13-type filler, weld hot and temper immediately below the last tempering temperature to avoid cracking.
Can H21 be formed, bent or molded?
Hot work at 1050–1150 °C with slow furnace cooling and mandatory soft anneal (~870 °C, slow cool) afterwards; no meaningful cold formability.
What surface finishes work on H21?
Takes a good polish when hardened; protect with oiling, phosphate, nitriding or PVD/chromizing since bare surfaces rust and suffer hot washout.
H21 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 | 0.26 – 0.36 | 0.31 |
| Si | 0.15 – 0.5 | 0.3 |
| Mn | 0.15 – 0.4 | 0.3 |
| Cr | 3 – 3.75 | 3.4 |
| Wprimary hot-hardness element | 8.5 – 10 | 9.25 |
| V | 0.3 – 0.6 | 0.45 |
| Moresidual / optional | ≤ 0.5 | — |
| Niresidual | ≤ 0.3 | — |
| Curesidual | ≤ 0.25 | — |
| P | ≤ 0.03 | — |
| S | ≤ 0.03 | — |
| Fe | balance | — |
H21 Nitrided — frequently asked
What is H21 Nitrided used for?
H21 Nitrided is typically used for brass and copper-alloy extrusion dies, hot punches and piercing points, hot forging die inserts, hot shear blades, extrusion mandrels and dummy blocks and die-casting dies for copper alloys. In short: hot-work tool steel.
What is the yield strength of H21 Nitrided?
H21 Nitrided has a typical yield strength of 1,450 MPa (210 ksi) and a tensile strength of 1,700 MPa (247 ksi) — stronger than 97% of steel grades. Strength varies by condition: see the 7 listed tempers.
Is H21 Nitrided easy to machine?
Not especially — machinability is rated not recommended (5/100, worse than 100% of steel grades). Machine only in the annealed condition (≤241 HB) with rigid setups and coated carbide; tungsten carbides are abrasive so keep speeds moderate, and finish-grind after hardening.
Can H21 Nitrided be welded?
Not readily — weldability is rated not recommended (5/100). Repair welding only: preheat 400–500 °C, matching W-alloy or H13-type filler, weld hot and temper immediately below the last tempering temperature to avoid cracking.
What surface finishes work on H21 Nitrided?
Takes a good polish when hardened; protect with oiling, phosphate, nitriding or PVD/chromizing since bare surfaces rust and suffer hot washout.
Can H21 Nitrided be formed, bent or molded?
Hot work at 1050–1150 °C with slow furnace cooling and mandatory soft anneal (~870 °C, slow cool) afterwards; no meaningful cold formability.
What is the maximum service temperature of H21 Nitrided?
H21 Nitrided is rated for continuous use to about 600°C (1,112 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Can FabDigit make parts in H21 Nitrided?
Yes — H21 Nitrided is available for CNC machining; every part is priced by an engineer rather than instantly. Upload a STEP file to get a price and a DFM check.
Sources
- ASTM A681 – Standard Specification for Tool Steels Alloy — ASTM International (2015)
- GB/T 1299 (3Cr2W8V) — SAC (2014)
- ASM Handbook Vol.1 – Properties and Selection: Irons, Steels, and High-Performance Alloys (Tool Steels) — ASM International (1990)
- Tool Steels, 5th ed. (Roberts, Krauss, Kennedy) — ASM International (1998)
- X30WCrV9-3 / 1.2581 hot-work tool steel datasheet — Böhler / Ovako-class producers (2020)
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.