As a knife maker, you must be well aware that Japanese knives are manufactured using HAP40 steel. As the steel possesses a great amount of durability and toughness, it is popular amongst knife-making companies in the U.S market.


The use of HAP40 steel is seen in the making of high-quality chef knives in Japan. Famous companies like Spyderco also use this steel for the manufacturing of pocket knives as well. There are more details that you can get to know, keep on reading!


What is HAP40 Steel?

HAP40 is the product of Hitachi Metals Limited, which is manufactured using the Powdered Metallurgy process. Formula-wise, the steel has a high carbon content that induces great edge retention, and a perfect balance of toughness and hardness of the steel.


The Japanese steel has a fine microstructure in its composition that makes a great choice for knife making of various types which including cleavers, kitchen knives, kitchen shears, utility knives, paring knives, and lastly chopping knives. This knife steel has proven a lot of times that it can take heavy impact and regular use without taking on much damage.


Chemical Composition: 

Unfortunately, the chromium content of the steel is less than 13% which results in the steel not being stainless. Other elements contribute to various other properties of the steel. Check them out.

  • 1.27-1.37% of Carbon: Helps to bring improvement to hardness, metal strength, and wear resistance as well.  
  • 3.70-4.70% of Chromium: Increases corrosion resistance, hardness, edge retention, tensile strength and toughness.
  • 5.60-6.40% of Tungsten: Enhances strength of the steel, hardenability, and toughness level.
  • 4.60-5.40% of Molybdenum: Increases hardness level, hardenability, and toughness level.
  • 2.80-3.30% Vanadium: Brings improvement to toughness level, steel strength and wear resistance.
  • 7.50-8.50% Cobalt: Boosts all the properties of the steel.


The hardness of the steel: 

According to the rating on the Rockwell scale, HAP40 steel has a hardness level ranging between 64 to 67 HRC. The hardness rating can vary depending on the heat treatment done on the steel. The rating shows that HAP40 steel has an incredible amount of hardness which is because of the chemical composition and evenly distributed microstructure.


Steel Properties: 

  • Great Toughness: As the chemical composition of HAP40 steel has a perfect balance of all the elements, the steel has a great toughness even after having a high hardness rating. The chemical composition consists of elements like cobalt, molybdenum, tungsten and vanadium. All these elements work together to ensure that the steel doesn’t break, crack or chip upon heavy duty.
  • Excellent Edge Retention: A lot of knife makers proudly accept HAP40 steel as one of the best Japanese steels because of its amazing performance in terms of edge retention. You can simply forget about sharpening the edge for a good number of days even after regular heavy use.
  • High Wear Resistance: As the steel has an immense hardness level it is obvious for it to have high wear resistance as well. Along with that fact, a blend of some essential elements also works for the steel to have high wear resistance.
  • Weak Corrosion Resistance: The percentage of chromium in HAP40 steel is below 13% which is not enough for the steel to be stainless. This results in poor corrosion resistance. Yet, knife makers came up with the idea of covering the surface of the steel with an anti-corrosion layer that protects the steel from catching corrosion and rust. Proper maintenance like cleaning and drying the steel after every use and also oiling the steel for keeping rust and corrosion at bay.
  • Ease of Sharpening: It is not easy to sharpen the HAP40 steel because of its extreme level of hardness. A whetstone will help you give the steel perfect edge that is capable enough to slice something thin like the hair into half.


Comparing HAP40 steel with other knife options: 

HAP40 vs ZDP189

Both of these steels have a similar carbon content in their chemical composition, making them both high carbon sheets of steel. Yet, HAP40 steel beats ZDP189 in terms of toughness because of the blend of other various elements. It is also easier to sharpen and give HAP40 steel a fine edge compared to ZDP189 steel.


However, HAP40 steel has amazing edge retention yet it loses the edge retaining capability of ZDP189. It is also better than HAP40 steel in terms of corrosion resistance as it has a higher percentage of chromium in its composition than HAP40.


HAP40 vs VG10

VG10 steel gets defeated by HAP40 steel in terms of toughness and ease of sharpening. However, VG10 is stainless steel with a higher chromium percentage that beats HAP40 steel in terms of corrosion resistance.


HAP40 vs S30V

S30V and HAP40 steel have great differences in properties as they have different formulas. HAP40 was designed to be high carbon steel whereas S30V was designed to be stainless steel which makes it better at corrosion resistance compared to HAP40.


Furthermore, if you are a knife maker in the U.S you will get S30V easily available to you as it is manufactured there. HAP40 on the other hand is Japanese steel manufactured by Hitachi Metals Limited.HAP40 beats S30V in terms of edge retention and wear resistance because high carbon steels tend to be very durable with a high hardness rating.


So, is HAP40 a Good Knife Steel?


Yes, HAP40 steel is an adequate choice for knife making considering the perfect balance of toughness and hardness in the steel. The steel has great edge retention which allows you to manufacture large-sized chef knives that will not break and chip easily. There is only one flaw about HAP40 which is that it is not stainless. However, we recommend using an anti-corrosion layer on the steel blade after using the steel for manufacturing blades.


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