HAP40 is a Japanese powder high-speed steel that runs very hard. It has appeared in Spyderco sprint runs and some Japanese kitchen knives.
HAP40 Steel at a Glance
| Type | Powder metallurgy (PM) steel |
|---|---|
| Made by | Hitachi Metals, now Proterial (Japan) |
| Typical hardness | 64-66 HRC |
| Key elements | Carbon about 1.3%, chromium about 4%, molybdenum about 5%, vanadium about 3%, tungsten about 6%, cobalt about 8% |
| Edge retention | 8/10 (very good) |
| Toughness | 4/10 (modest) |
| Rust resistance | 3/10 (modest) |
| Ease of sharpening | 3/10 (hard) |
| Best for | Very hard, Spyderco sprints |
Ratings are relative 1 to 10 scores for typical factory heat treatments. See how HAP40 ranks against 46 other steels in our Knife Steel Chart.
What Is HAP40 Steel?
HAP40 is similar to M4 with added cobalt, which lets it reach very high hardness. It is made by powder metallurgy for fine carbides.
HAP40 Steel Properties
- Edge retention: Very good.
- Toughness: Modest.
- Rust resistance: Modest. Keep it dry and lightly oiled.
- Ease of sharpening: Hard. Use diamond or CBN stones.
HAP40 vs Other Steels
HAP40 vs CPM M4
Compared with CPM M4, HAP40 resists rust slightly better. CPM M4 is tougher. Read our CPM M4 guide.
HAP40 vs Maxamet
Compared with Maxamet, HAP40 is tougher, resists rust slightly better and is easier to sharpen. Maxamet holds an edge longer. Read our Maxamet guide.
HAP40 vs ZDP-189
Compared with ZDP-189, HAP40 is tougher and is slightly easier to sharpen. ZDP-189 holds an edge slightly longer and resists rust better. Read our ZDP-189 guide.
Is HAP40 Steel Good for Knives?
Yes, for slicing and EDC in experienced hands. Keep it dry and avoid prying.
Pros:
- Very high hardness
- Very good edge retention
Cons:
- Not stainless
- Lower toughness at high hardness
- Hard to sharpen
Knives That Use HAP40 Steel
Makers sometimes change blade steels between versions, so check the listing to confirm the steel before you buy.
Frequently Asked Questions
Is HAP40 steel stainless?
No. HAP40 is not stainless and will rust or patina if left wet. Keep it dry and lightly oiled.
How hard is HAP40 steel?
Knives in HAP40 are usually heat treated to around 64-66 HRC.
Is HAP40 easy to sharpen?
Hard. Diamond or CBN stones work best.