Steel H21
AISI/SAE H21 · UNS T20821 · EN 1.2581 · GB 3Cr2W8V
H21 is a tungsten-type hot-work tool steel (~3.5 % Cr, 9 % W; T20821, 1.2581, 3Cr2W8V) offering high hot hardness and resistance to erosion, traditionally used for hot-working tools that run at elevated temperature without water cooling.
Values for the Annealed condition
H21 tempers and conditions
H21 is supplied in 7 conditions, soft to hard. Annealed is the default FabDigit quotes; the values on this page are for it.
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 | — |
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?
H21 is a tungsten-type hot-work tool steel (~3.5 % Cr, 9 % W; T20821, 1.2581, 3Cr2W8V) offering high hot hardness and resistance to erosion, traditionally used for hot-working tools that run at elevated temperature without water cooling. It is supplied annealed, hot-rolled, nitrided or quenched and tempered to 38–42, 44–48 and 50–54 HRC; annealed bar lists 620 MPa yield, 900 MPa tensile, 18 % elongation and 220 HB. Machinability is limited (score 40) by the abrasive tungsten carbides, and weldability is restricted to controlled repair work; H13 is the usual alternative where thermal-fatigue resistance and water cooling matter more than hot hardness. H21 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). H21 has a yield strength of 620 MPa (89.9 ksi) and a tensile strength of 900 MPa (131 ksi) — stronger than 78% of steel grades. Elongation at break is 18% and the elastic modulus is 210 GPa (30.5 Msi).
What is H21 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
- Die-casting dies for copper alloys
- Hot upsetting tools
Advantages
- High service temperature — 450°C (842 °F), better than 86% of steel grades
- High strength — 620 MPa (89.9 ksi), better than 78% of steel grades
- Polishes to a fine finish — 65/100, better than 78% of steel grades
Limitations
- High embodied carbon — 3 kg CO₂/kg, worse than 91% of steel grades
- Low electrical conductivity — 3.1 % IACS, worse than 89% of steel grades
- Poor heat conductor — 27 W/m·K (15.6 BTU/hr·ft·°F), worse than 86% of steel grades
- Low fracture toughness — 55 MPa·√m (50.1 ksi·√in), worse than 82% of steel grades
- Limited formability — 20/100, worse than 80% of steel grades
H21 properties
Typical room-temperature values for H21-Annealed; bars are the position among steel grades.
Physical3
H21 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 has a yield strength of 620 MPa (89.9 ksi) and a tensile strength of 900 MPa (131 ksi) — stronger than 78% of steel grades. Elongation at break is 18% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
H21 is rated for continuous service to 450°C (842 °F). It conducts heat at 27 W/m·K (15.6 BTU/hr·ft·°F), worse than 86% of steel grades. Thermal expansion is 11.8 µm/m·K (6.56 µin/in·°F).
Electrical3
H21 conducts electricity at 3.1 % IACS, worse than 89% of steel grades.
Chemical & Environmental2
Corrosion resistance is poor (15/100), better than 75% of steel grades.
Sustainability4
Producing a kilogram of H21 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's machinability is fair (40/100, worse than 77% of steel grades); weldability fair (35/100); formability poor (20/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the steel family
Yield strength against density for every steel grade FabDigit runs. H21 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with H21
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.
Manufacturability
The process limits FabDigit applies to H21. Every H21 part is priced by an engineer; design inside these and the quote comes back without a redesign loop.
CNC machining
| Machinability | Fair40 / 100 |
|---|---|
| ISO material group | P.2 |
| Cutting speed (rough / finish) | 180 / 210 m/min |
| Minimum wall | 0.8 mm |
| Minimum internal radius | 1 mm |
| Drill depth limit | 5× diameter |
| Best surface (machined / polished) | Ra 1.6 / — |
| Hardenable after machining | No |
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 |
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.
Surface treatments FabDigit runs on steel parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
Plating
CVD Coating
Black / Phosphate
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Steel H21 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- T20821
- EN / DIN / Werkstoff-Nr.
- 1.2581
- GB (China)
- 3Cr2W8V
How much does H21 cost?
H21 is a standard-cost steel ($$), cheaper than about 71% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
H21 — frequently asked
What is H21 used for?
H21 is typically used for brass and copper-alloy extrusion dies, hot punches and piercing points, hot forging die inserts, hot shear blades, extrusion mandrels and dummy blocks and die-casting dies for copper alloys. In short: hot-work tool steel.
What is the yield strength of H21?
H21 has a typical yield strength of 620 MPa (89.9 ksi) and a tensile strength of 900 MPa (131 ksi) — stronger than 78% of steel grades. Strength varies by condition: see the 7 listed tempers.
Is H21 easy to machine?
Not especially — machinability is rated fair (40/100, worse than 77% of steel grades). Machine only in the annealed condition (≤241 HB) with rigid setups and coated carbide; tungsten carbides are abrasive so keep speeds moderate, and finish-grind after hardening.
Can H21 be welded?
With care — weldability is rated fair (35/100). Repair welding only: preheat 400–500 °C, matching W-alloy or H13-type filler, weld hot and temper immediately below the last tempering temperature to avoid cracking.
What surface finishes work on H21?
Takes a good polish when hardened; protect with oiling, phosphate, nitriding or PVD/chromizing since bare surfaces rust and suffer hot washout.
Can H21 be formed, bent or molded?
Hot work at 1050–1150 °C with slow furnace cooling and mandatory soft anneal (~870 °C, slow cool) afterwards; no meaningful cold formability.
What is the maximum service temperature of H21?
H21 is rated for continuous use to about 450°C (842 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does H21 cost?
H21 is a standard-cost steel ($$), cheaper than about 71% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Can FabDigit make parts in H21?
Yes — H21 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; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.