As a knife enthusiast, you surely did come across many tool steels. So, the name of O1 steel does not remain unknown to you since the steel is famously used by manufacturers for the making of custom knives and tools as well. Curiosity might rise when you think about what makes O1 steel a good knife steel. That is why we are here to go in-depth about the chemical composition, steel properties and comparisons with other steels.


What is O1 Steel?

O1 steel was manufactured in 1905 by a company named Halcomb which is now developed by an American steel company called Crucible. The O1 steel belongs to the O series of the company. All the steels of that series are manufactured by oil quenching which makes O1 steel an oil hardening tool.


Like usual steels, O1 steel is not quenched in water but in oil. This manufacturing process makes O1 steel preferred by manufacturers for the making of tools and knives that require a high level of hardness that is not found in other steel types. Tool steels have an immense amount of hardness than usual steels so they stay in their actual form even after enduring high temperatures. All tool steels are carbon alloys with the required features for the manufacturing of hand tools, machine dies, and usual tools.


O1 is one of the popular options amongst tool steels. You will witness manufacturers opting for O1 for the making of industrial machine knives, EDC knives, punches and working tools.


Chemical Composition:

O1 is classified as high-carbon steel due to the high percentage of carbon in its chemical composition. The chromium level is low which does not make it stainless steel.

  • 1% of Carbon: Enhances hardness and improves the ability of the steel to resist corrosion and wear.
  • 0.6% of Chromium: Boosts tensile strength, edge retention, and ability of the steel to resist corrosion and wear.
  • 1.4% of Manganese: Adds dimensional stability, hardness and enforceability.
  • 0.6% of Tungsten: Increases wear resistance and hardness level.
  • 0.5% of Silicon: Improves steel strength.
  • 0.3% Nickel: Increases toughness level.
  • 0.3% of Vanadium: Boosts hardenability and wear resistance.
  • 0.03% of Sulphur: Improves machinability.
  • 0.03% of Phosphorus: Adds steel strength.


Steel Hardness: 

According to the Rockwell C scale, the hardness rating of O1 ranges between 57 to 62 HRC. The actual rating of the steel is 57 HRC but it can level up to 62 HRC depending on the heat treatment provided to the steel. The rating is considered high and it is because of the high amount of carbon present in its composition. The 57 HRC rating of the steel is perfect for the manufacturing of EDC knives and the higher rating is adequate for manufacturing outdoor and survival knives that will require heavy duty under tough conditions.




Steel Properties: 

  • Surprising toughness: A steel with a high hardness rating is bound to have a low toughness level. You will find steels with high hardness are vulnerable to chipping and are brittle. But the case with O1 steel is surprisingly different. Even with a high hardness rating O1 has the required toughness to resist chipping. This makes O1 an ideal option for manufacturing outdoor knives like bushcraft, camping, and survival knives. You can easily use steel for wood carving and cutting hard materials.
  • Excellent wear resistance: With the hardness rating that O1 steel has it is not unexpected for it to deliver incredible performance for resisting wear. This feature of O1 makes it a desirable steel for the manufacturing of various types of knives. The credit for the excellent wear resistance also goes to the presence of carbon, manganese and vanadium in its chemical composition. This helps O1 steel blades last for a long period even after being used frequently.
  • Great edge retention: Due to the high hardness level you will witness superb capacity in O1 for edge retention. The knives made out of O1 steel are capable of retaining the edge for a long time without requiring frequent resharpening. This feature makes the knife suitable for the manufacturing of outdoor and survival knives.
  • Weak corrosion resistance: This is the only feature that holds O1 steel back. The steel is not good at keeping corrosion at bay. The low chromium percentage is the reason to blame. You will require to maintain the blade by drying it off after cleaning. Using oil to lubricate also helps to keep rust and corrosion away.
  • Ease of sharpening: Even after having high hardness the steel is easy to sharpen. The steel easily keeps its sharpness for a long time. Even if you are a beginner you will find it easy to sharpen the edge of the blade made out of O1. Using a regular sharpener for O1 is enough.


Comparison with Other Knife Steel Options

O1 vs A2

O1 has the capacity of attaining sharper edges quicker than A2 and also requires less effort for sharpening. But because of higher chromium content, A2 beats O1 in terms of corrosion resistance.


O1 vs 1095

1095 has no chromium at all. This makes O1 superior at having better capacity, resisting corrosion and wear and also has better toughness and machinability than 1095.


O1 vs D2

D2 differs from O1 as D2 is an air-hardening tool steel with higher chromium content than O1. This makes A2 better at edge retention and resistance towards corrosion and wear. But, O1 takes the crown for having higher toughness and being easy to sharpen.


O1 vs S30V

S30V is stainless steel with better performance at corrosion resistance and edge retention than O1. On the other hand, O1 beats S30V in toughness and is also more affordable in price.


O1 vs 1084

Both steels are versatile and are popular for manufacturing knives. However, O1 is the harder steel with better ability in wear resistance due to the presence of tungsten. But, 1084 is more affordable in terms of price than O1.


So, is O1 a Good Knife Steel?

Yes, O1 is an ideal steel for manufacturing both knives and tools. The steel has the perfect balance between toughness and hardness which makes it a popular choice amongst knife manufacturers. The only feature holding the knife steel is its weak corrosion resistance which you can overcome with proper maintenance.




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