HAP40/SUS410 steel is laminate steel, whereby HAP40 steel, which is not stainless steel, is coated with SUS410 stainless steel. The stainless steel protects the blades made from rusting and corrosion. When you take a closer look at the blade, you will notice the unique layer construction above the cutting edge just after the blade grind.

The blend of elements from HAP40 and SUS410 gives HAP40/SUS410 laminated tool steel an excellent balance of hardness, toughness, edge retention, wear-resistance, and corrosion resistance. What’s more, it has a fine microstructure that makes it easy to sharpen.

However, SUS410 is soft martensitic stainless steel, making the blades highly SUSceptible to wear and damage. The blade part with SUS410 can get scratches quickly when used for challenging applications.

HAP40/SUS410 laminated tool steel is excellent knife steel mainly used by the Spyderco lineup. You will find in limited Spyderco dragonfly, Spyderco Endura, Endela, and Spyderco Delica.

Properties of HAP40/SUS410 steel

HAP40/SUS410 Steel Hardness

The Rockwell hardness of the HAP40/SUS410 steel cutting edge part ranges between 64-68HRC. This makes it hard steel, but the exact hardness differs from the heat treatment, particularly HAP40 steel.

The steel can achieve high hardness because of the high amounts of carbon in the HAP40 alloy composition and the fine microstructure.

HAP40/SUS410 Steel Toughness

It is a rule of thumb that steel offers either high hardness or high toughness but not both. Because of its high hardness, HAP40/SUS410 steel is expected to perform poorly in toughness.

However, this is not the case; the steel offers decent toughness thanks to the perfect mixture of cobalt, molybdenum, tungsten, and vanadium. HAP40/SUS410 steel toughness is better than most stainless steel out there like BD1N stainless steel, M390, and CPM S45VN Steel.

The hardness and toughness balance offered by HAP40/SUS410 makes it stand out among tough steels. Knives made from this steel do not break, chip, or crack when used for tough applications due to their decent toughness.

HAP40/SUS410 Steel Edge retention

With a high hardness of 68HRC, HAP40/SUS410 steel offers excellent edge retention. Knives made from this steel can be used for repetitive cutting tasks with little need for sharpening. 

The excellent edge retention is associated with the high hardness of HAP40 steel. If you are out for knives that will serve you for long without the need to sharpen, the varieties of HAP40/SUS410 laminate steel will never disappoint you.

HAP40/SUS410 Steel Wear resistance

Another area of excellence for this steel is its wear resistance. HAP40 /SUS410 knives will serve you across generations even with regular usage. The excellent wear resistance is associated with the HAP40 steel’s high hardness.

It is worth noting that the coating SUS410 stainless steel on HAP40 steel will easily pick up scratches and scuffs especially during use and sharpening of the blade.

This will greatly affect the corrosion resistance of the blade, as the high carbon HAP40 steel is hugely SUSceptible to rusting and corrosion.

HAP40/SUS410 Steel Corrosion resistance

HAP40/SUS410 laminate steel offers excellent corrosion resistance. This is highly attributed to the stainless steel SUS410 coated over the semi-stainless HAP40 steel.

HAP40 Steel on its own is poor in corrosion resistance, however, SUS410 stainless steel is great in corrosion resistance as it contains about 13.5% chromium elements in its alloy composition.

This combination enables the core HAP40 steel to perform excellently in cutting while the SUS410 steel protects the HAP40 from corrosion.

Sharpening HAP40/SUS410 steel

HAP40/SUS410 steel is not easy to sharpen, which is expected because it is hard steel with excellent wear resistance. However, this is not to say that the blades cannot be sharpened. 

The sharpening process will take up a lot of time and energy, but you will eventually get a razor-sharp edge with the right skills and sharpening tools. 

While sharpening, I would advise covering the blade to only expose the cutting edge as the laminate SUS410 stainless steel is very soft and can easily pick up scratches and scuffs from abrasion. 

Comparison of HAP40/SUS410 steel

HAP40/SUS410 vs ZDP189 Stainless Steel

ZDP189 and HAP40/SUS410 steels contain a high carbon steel family but with varying properties. ZDP189 contains higher amounts of carbon and chromium than its counterpart, offering high hardness which translates to better edge retention.

A ZDP189 stainless steel blade will thus offer better edge retention than the laminate HAP40/SUS410 steel blade.

While ZDP189 stainless steel contains a high amount of chromium in its composition, its corrosion resistance is a bit low. HAP40/SUS410 steels laminate steel will offer better corrosion resistance due to the highly stainless SUS410 steel.

HAP40/SUS410 steel laminate will also provide better toughness than ZDP189 stainless steel due to the reduced hardness level.

ZDP189 contains a high volume of large chromium carbides which are extremely hard and brittle. This lowers ZDP189 steel toughness considerably.

HAP40/SUS410 vs. VG10 Stainless Steel

Japanese VG10 is stainless steel with 15% chromium in its composition; therefore, it offers better corrosion resistance than the laminate HAP40/SUS410 steel.

In terms of edge retention, HAP40/SUS410 beats VG10 by a considerable margin as HAP40 is exhibit high hardness with excellent edge retention. 

Its edge retention is comparable to CPM M4 steel, while VG10 stainless steel is comparable to that of  Bohler N690 stainless steel and AISI 440C stainless steel.

HAP40/SUS410 steel will also offer slightly better toughness than VG10 steel, which can be attributed to HAP40 steel being powder steel with a better production process.

The toughness of a HAP40/SUS410 laminate steel is comparable to that of 1095 steel, while VG10 stainless steel toughness is like that of S45VN and Elmax stainless steel.

Is HAP40/SUS410 good knife steel?

HAP40/SUS410 laminate steel offers high hardness, excellent wear resistance, edge retention, decent toughness, and great corrosion resistance, making it good knife steel.

The core high hardness HAP40 steel is responsible for cutting and edge retention. The performance of HAP40 steel is highly comparable to CPM Rex 45 steel. The softer SUS410 laminate stainless steel protects the blade from corrosion.

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