H23 vs H21
These two grades are listed as equivalents of each other: their chemistry windows overlap and they serve the same applications. They are not always identical — check the differences below before substituting, especially in certified designs.
H23
Tool Steel
H23 pairs about 12% chromium with 12% tungsten for hot work at the top of the temperature range, where oxidation and softening defeat lower-alloy dies. It is a niche grade for the hottest extrusion and forging contact surfaces.
Standards: AISI H23
H21
Tool Steel
H21 is the classic 9% tungsten hot work steel, long the standard for brass extrusion and hot die work in Asia as 3Cr2W8V. It holds hardness at die temperatures where chromium steels fade, at the cost of toughness.
Standards: DIN 1.2581 · AISI H21 · JIS SKD5 · GB 3Cr2W8V
Chemical composition compared (%)
| Element | H23 | H21 |
|---|---|---|
| C | 0.25–0.35 | 0.26–0.36 |
| Si | 0.15–0.60 | 0.15–0.50 |
| Mn | 0.15–0.40 | 0.15–0.40 |
| Cr | 11.00–12.75 | 3.00–3.75 |
| W | 11.00–12.75 | 8.50–10.00 |
| V | 0.75–1.25 | 0.30–0.60 |
Properties compared
| Property | H23 | H21 |
|---|---|---|
| Delivery condition | Annealed | Annealed |
| Working hardness | 35–45 HRC | 36–48 HRC |
| Density | 8.30 g/cm³ | 8.20 g/cm³ |
| Hot hardness | — | High (9% tungsten) |
Sourcing either grade?
Nasteel stocks both families from Shenzhen with EN 10204 3.1 mill certificates by heat number.
Ask for a quotationSee full data sheets: H23 · H21. Substitution decisions for certified parts stay with the design authority.