Steel H21 · temper · default condition
Steel H21 Annealed
Properties of the Annealed condition, compared with the other H21 tempers.
Standard stock condition for machining dies and inserts before hardening.
What is H21 Annealed?
H21 Annealed is H21 in the Annealed temper — standard stock condition for machining dies and inserts before hardening. H21 Annealed 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). H21 Annealed 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).
Advantages
- High service temperature — 600°C (1,112 °F), better than 98% 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
- Limited formability — 15/100, worse than 87% of steel grades
- Poor heat conductor — 27 W/m·K (15.6 BTU/hr·ft·°F), worse than 85% of steel grades
- Difficult to weld — 25/100, worse than 77% of steel grades
- Difficult to machine — 40/100, worse than 76% of steel grades
H21 Annealed properties
Typical room-temperature values for H21 Annealed — 9 properties are specific to this condition; the rest are grade-level values shared by every H21 temper. Each bar shows where the value sits among the steel grades in FabDigit's library — further right is higher.
Physical3
H21 Annealed 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).
Mechanical14
H21 Annealed 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 Annealed is rated for continuous service to 600°C (1,112 °F). It conducts heat at 27 W/m·K (15.6 BTU/hr·ft·°F), worse than 85% of steel grades. Thermal expansion is 11.8 µm/m·K (6.56 µin/in·°F).
Electrical2
H21 Annealed has an electrical resistivity of 5.5×10⁻⁷ Ω·m.
Chemical & Environmental2
Corrosion resistance is poor (15/100), better than 75% of steel grades.
Sustainability4
Producing a kilogram of H21 Annealed takes about 42 MJ of energy and emits 3 kg of CO₂ — more than 91% of steel grades. Typical recycled content is 45%.
Manufacturability8
H21 Annealed's machinability is fair (40/100, worse than 76% of steel grades); weldability poor (25/100); formability poor (15/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other H21 tempers and conditions
H21 is also supplied in 7 other conditions. The full side-by-side table is on the H21 overview.
- AnnealedDefaultStandard stock condition for machining dies and inserts before hardening.620 MPa yield · 220 HB
- Q&T 50-54 HRCChoose for hot shear blades and small punches where abrasive hot wear dominates and shock is low.1,600 MPa yield · 52 HRC
- Q&TGeneral hardened-and-tempered service condition for hot dies at 45–52 HRC.1,450 MPa yield · 49 HRC
- Hardened & TemperedDouble-tempered condition specified when maximum thermal-fatigue and softening resistance is required.1,350 MPa yield · 47 HRC
- Q&T 44-48 HRCMost common working hardness for hot extrusion dies, punches and brass die-casting inserts.1,350 MPa yield · 46 HRC
- Q&T 38-42 HRCPick for large hot-forging dies and dummy blocks where gross cracking, not wear, is the failure mode.1,100 MPa yield · 40 HRC
Working with H21 Annealed
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 Annealed — frequently asked
What is H21 Annealed used for?
H21 Annealed 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 Annealed?
H21 Annealed 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 8 listed tempers.
Is H21 Annealed easy to machine?
Not especially — machinability is rated fair (40/100, worse than 76% 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 Annealed be welded?
Not readily — weldability is rated poor (25/100). 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 Annealed?
Takes a good polish when hardened; protect with oiling, phosphate, nitriding or PVD/chromizing since bare surfaces rust and suffer hot washout.
Can H21 Annealed 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 Annealed?
H21 Annealed 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 Annealed?
Yes — H21 Annealed is available for CNC machining with instant online pricing. 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.