HAP40 steel is high-speed tool steel produced by a Japanese company by the name Hitachi metals following the Powdered Metallurgy process.
The mixture of components used to make HAP40 steel gives it a balance of hardness, toughness, and edge retention.
HAP40 is not stainless steel because its chromium content does not meet the levels needed to make it stainless steel. You would expect it to rust easily, but the small amounts of chromium offer considerable corrosion resistance.
Its fine microstructure and composition make it suitable for the manufacture of chopping knives, paring knives, cleavers, kitchen shears, and utility knives.
HAP40 Steel Chemical composition
- Carbon C 1.37%: Increases the edge retention, hardness and tensile strength. It also improves steel resistance to wear, abrasion and corrosion.
- Chromium Cr 4.70%: Formation of Chromium carbide Increases hardness, tensile strength and toughness of the blade.
- Molybdenum Mo 5.40%: It improves machinability and hardness.
- Vanadium V 3.30%: Increase wear resistance and toughness, it also improves corrosion resistance. High vanadium content enables formation of Vanadium Carbide giving S30V an edge over other steel that rely on Chromium Carbides in wear resistance.
- Nitrogen N 0.20%: Adds Toughness to the blade, acts similar to Carbon in alloys.
- Tungsten W 6.50%:Improves wear resistance and hardness, mostly added to tool steel.
- Cobalt Co 8.50%: Forms hard carbide in combination with other elements improving hardness.
HAP40 Steel Hardness
HAP40 steel hardness is 64-68HRC according to the Rockwell hardness scale, making it hard steel. However, the hardness level varies depending on the heat treatment used by the manufacturer.
The high hardness of this steel is associated with its chemical composition and fine microstructure.
HAP40 Steel Edge retention
HAP40 steel offers a high level of hardness and hence great edge retention. If you are on the market for a knife that will help you in a lot of cutting without losing an edge faster, look into the varieties of HAP40 knives.
HAP40 Steel Corrosion resistance
As already mentioned, HAP40 steel does not contain large amounts of Chromium in its composition which affects its corrosion resistance capabilities. We cannot say that it offers the worst corrosion resistance out there, but it performs poorly compared to other high-end steels.
However, with proper care and maintenance, the small chromium levels can protect your knife from rusting.
What’s more, knife makers laminate HAP40 knives with anti-corrosion finishes to protect them from rusting.
HAP40 Steel Toughness
Many types of steel can either offer you hardness or toughness but not both. With the HAP40 steel offering extreme hardness, we would expect a low performance in toughness but this is not the case.
This steel is admired because of its great toughness, which is associated with a perfect mix of Molybdenum, Vanadium, Tungsten, and Cobalt in its composition.
HAP40 knives will not break, chip, or crack easily when used on tough applications, a feature that makes knife makers choose it over and over.
HAP40 Steel Wear resistance
Another property that benefits from the high hardness of HAP40 is its wear resistance. Despite regular usage, HAP40 knives will serve you across generations and especially if they had a quality handle.
Sharpening HAP40 Steel
Being hard steel with great wear resistance, HAP40 steel is not easy to sharpen. However, with the right sharpening skills and stones, you can easily get a razor-sharp edge.
The ability to gain a very sharp edge is associated with its fine microstructure.
Despite the difficulty in sharpening this steel, it remains sharp for a long meaning that you do will not go through the sharpening hustle frequently.
HAP40 steel equivalent
HAP40 vs ZDP189
Both HAP40 and ZDP-189 steel belong to the high carbon steel family. However, HAP40 steel performs better in toughness, it is easier to sharpen and gains a sharp edge faster.
On the other hand, ZDP189 shines in edge retention and corrosion resistance because it contains high Chromium levels.
HAP40 vs S30V
The first notable difference is that S30V steel is stainless steel while HAP40v is carbon steel. Therefore, S30V is a better choice for knives to be used in corrosive environments.
What’s more, S30V is easier to sharpen while HAP40 remains sharp for long.
HAP40 vs VG10
Both types of steel feature good steel knife properties, but HAP40 steel beats VG10 steel in toughness, edge retention, and ease of sharpening.
On the other hand, VG10 steel outshines its counterpart in corrosion resistance because it is stainless steel and contains high amounts of Chromium.
Is HAP40 good knife steel?
HAP40 steel is good knife steel because it offers great hardness, edge retention, wear resistance, and toughness. Although it does not qualify as stainless steel, it offers decent corrosion resistance making it a good choice for knife making.
You will also find HAP40 steel laminated by SUS410 steel in some Spyderco knives and referred to as HAP40/SUS410 laminate tool steel. The laminate tool steel offers good edge retention with improved corrosion resistance from stainless steel SUS410 steel.