What is HAP40 Steel?

If you are a knife enthusiast, you know how important the blade of a knife is. No blade is the same and each blade will have some good qualities that other blades may lack.

Japanese knives are great because of their thin blades and sharpness. If you are looking for a blade with a focus on sharpness, you have probably come across the HAP40 steel.

Well, how good is it, and what goes in the steel? Let find out.

What is HAP40 Steel?

HAP40 steel is a Japanese steel that is common with knife makers and knife users. You have probably heard of how hard the steel can get. Hitachi Metals Ltd makes this powder metallurgy tool steel and it has a great combination of elements giving it high-end steel features. It is exceptionally hard, tough, and it has great wear resistance and edge retention. The steel is however susceptible to rust and it is hard to sharpen.

Composition of HAP40 steel

Let’s begin with the composition of the steel. This steel has a unique combination of components at high quantities which gives it high-quality features.

They include:


Cobalt is in high amounts in HAP40 steel at 8.5%. HAP40 is an HSS (High-Speed Steel) and Cobalt is a vital element in high-speed steels.

It increases the red hardness and high heat resistance of the steel while also enhancing its bonding strength.

Knife makers use high-speed steels in making cutting tools like power saw blades and drill bits. Cobalt works to increase the cutting properties of the steel.


Tungsten is another element in HAP40 at a good 6.5%. It has high melting temperatures which increase the melting points of the steel.

Being hard too, Tungsten enhances the wear resistance of HAP40.

Molybdenum and Vanadium

Molybdenum at 5.4% and Vanadium at 3.3% work in improving the wear resistance, strength, and hardness of steel. Molybdenum is also good for weldability.


HAP40 steel has very low Chromium amounts. At only 4.7%, the steel is not stainless or resistant to rust.

This is because all steel requires at the very least 10.5% Chromium to become stainless.

HAP40 steel has small amounts of Chromium but even though this can’t keep the steel free from rust, it is enough to strengthen it, toughen it, and give it good wear resistance.


Carbon is high in HAP40 steel at 1.27%. Being so high, the Carbon provides it with high hardness and wear resistance.

HAP40 steel hardness

The steel is very hard and it has an over the top Rockwell hardness of 66-68 HRC which is very impressive.

Properties of HAP40 steel

HAP40 steel has a unique combination of elements which give it its great properties. They include:

Impressive edge holding

HAP40 steel is very hard steel and what does that give you? Some very impressive edge holding capacity.

The blades made from the steel can stay sharp for really long periods. If maintaining an edge through constant sharpening is your weakness, this steel has got you covered.

High Durability

HAP40 steel is very durable and it will last you long without wearing out. It has high wear resistance due to the combination of Tungsten, Vanadium, Cobalt, and Molybdenum.

This gives you a high-end knife with high durability.

Great Toughness

HAP40 steel is very tough and doesn’t chip. You can use it for hard cutting and that is why it’s applied in cutting tools.

Mostly, if the steel is hard, it becomes less tough. And if it’s tough, it is not very hard. But HAP40 steel carries both qualities.


The steel is not easy to sharpen. If steel is hard then it becomes hard to sharpen too.

You may spend a considerable amount of time getting it to a good level of sharpness. This is not what you would like to hear if you are not very patient but the good thing is that it will hold that edge for ages.

Low Corrosion Resistance

The steel has very low corrosion resistance. This is due to the low amounts of Chromium in it at 4.7% which is really low.

Low Chromium amounts lower the corrosion resistance of HAP40 making it an unsuitable choice for humid environments. This is because the steel is highly susceptible to corrosion and rust.

However, you can keep it in good condition by taking the following measures:

  • Always clean your blade after use.
  • Never leave the blade wet. Make sure you dry it at all times before storage.
  • Oil it regularly. You can apply some vegetable oil or Vaseline on the blade after every week to prevent oxidation.
  • Do not wash the knife in the dishwasher.

Is HAP40 steel good for knives?

HAP40 steel is good for knives. It has very high levels of hardness, toughness, edge retention, and wear resistance.

The steel can take hard use very well. However, it has low corrosion resistance which leads to it rusting fast. It’s not suitable for wet activities like fishing, hunting, or kitchen use. You will have to give it some extra maintenance from time to time.

HAP40 Steel comparisons

Every steel will have one or more steels that it compares with. For HAP40 steel, it’s the CPM M4 steel.

They have close composition and properties like high hardness, toughness, great edge retention, wear resistance, and not too good corrosion resistance.


HAP40 steel is one of the best knife steels you will ever find. It is high-end steel so you can be sure to get all the great properties of high-quality steel with the blade.

It has an exceptional hardness, toughness, and wear resistance. It may be quite hard to sharpen but after attaining that perfect level of sharpness it will stay for a very long time before you need to sharpen it again.

Also, it doesn’t have good corrosion resistance. You will have to maintain it properly to keep it in top condition.

All in all, it’s great steel with very good features. It’s well worth your money.

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