H21
Data verifiedH21 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.
Chemical composition
| Element | Content (%) |
|---|---|
| C | 0.26–0.36 |
| Si | 0.15–0.50 |
| Mn | 0.15–0.40 |
| Cr | 3.00–3.75 |
| W | 8.50–10.00 |
| V | 0.30–0.60 |
Weight percent, per the governing standard ranges. Actual values per heat are on the mill certificate.
Properties
| Delivery condition | Annealed |
| Working hardness | 36–48 HRC |
| Density | 8.20 g/cm³ |
| Hot hardness | High (9% tungsten) |
Heat treatment
Harden 1095–1200 °C air/oil (protect from decarburization); double temper 540–650 °C.
Equivalent grades
| Standard | Designation |
|---|---|
| din | 1.2581 |
| aisi | H21 |
| jis | SKD5 |
| gb | 3Cr2W8V |
Compare side by side: H21 vs 3Cr2W8V · H21 vs H19 · H21 vs H23
Equivalents overlap in chemistry and use but are not always identical — see our equivalents guide before substituting in certified designs.
Applications & Processing
Applications: Brass/copper extrusion dies, die casting dies for high-melting alloys, hot forging inserts, dummy blocks.
Processing: Brittle by hot-work standards — preheat dies before service and avoid thermal shock. Vacuum or salt-bath hardening preferred.
FAQ
- H21 vs H13?
- H21 keeps hardness hotter but is far less tough and more crack-prone. Modern aluminum work favors H13; H21 survives in brass extrusion and legacy Asian die shops.
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Ask for a quotationVisit NasteelSource: ASTM A681 / JIS G4404 published ranges · Last updated 2026-11-03. Data is indicative — verify critical values against the governing standard and mill certificate before use.