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What is 8670 Steel?
8670 steel is a carbon alloy steel produced by Admiral Steel under the 86xx series. It has carbon, nickel, chromium, and manganese as its main components giving it good hardness and toughness balance.
This steel is not very popular, which makes it costly, but due to its features, it is considered an alternative to some CPM steel.
8670 is popular in the making of band saws, circular saws, and large knives. Apart from it being rare, knife makers do not lean on this steel because it is not stainless steel.
It was a preferred choice for beginner knife makers due to its simple heat treatment.
8670 Steel Composition
- Carbon C 0.75%: Increases the edge retention, hardness and tensile strength. It also improves steel resistance to wear, abrasion and corrosion.
- Chromium Cr 0.50%: Formation of Chromium carbide Increases hardness, tensile strength and toughness of the blade.
- Molybdenum Mo 0.15%: It improves machinability and hardness.
- Nickel Ni 1.00%: Adds Toughness to the blade, acts similar to Carbon in alloys.
- Manganese Mn 0.60%: Increases Hardness and but in high quantities can increase brittleness of the steel.
- Silicon Si 0.35%: Increases strength and heat resistance.
- Phosphorus P 0.02%: Improves machinability and hardness.
- Sulfur S 0.02%: Improves machinability.
Properties of 8670 steel
8670 Steel Hardness
8670 steel hardness is 59 HRC as per the Rockwell hardness scale, and this varies with the heat treatment used. Some brands can get it to 61HRC with intense heat treatment. This hardness level is not the best among steel, but it is good enough to give this 8670 steel decent performance.
Many steels with this hardness range are easy to work with, which is true with 8670 steel. It is easy to work with in terms of forging, machining, and heat treatment.
8670 Steel Edge retention
With its level of hardness, it remains sharp for a decent time. This feature allows knife users to enjoy excellent sharpness and ease of knife sharpening. Its edge holding ability can be compared to that of A2 steel and slightly lower than that of 1.4116 steel.
8670 Steel Toughness
Apart from Z-tuff steel, 8670 steel toughness is unrivaled in the knife steel world. It offers outstanding toughness, a score of 10/10. The only few steels that come close to this are 5160, 14C28N, and CPM 3V.
8670 steel offers an outstanding balance between hardness and toughness because it is not very hard steel. Its level of hardness allows it to remain sturdy even when used for tough applications.
You do not have to worry that your 8670 knives will break or chip when used roughly. Its toughness is associated with the excellent blend of Carbon, Manganese, Chromium, and Nickel in its alloy.
If you are on the market searching for a knife that offers a decent balance between its hardness and toughness, you are in the right place because 8670 knives provide precisely that.
8670 Steel Wear resistance
This steel offers decent wear resistance, which is associated with the 0.75% Carbon in its composition. Since it is not very hard steel, there are steels with better wear resistance on the market than 8670, but this does not make it the poorest.
With its level of wear resistance, 8670 steel does not wear out quickly from applications that lead to wear and tear like frequent sharpening.
8670 Steel Corrosion resistance
8670 steel contains low amounts of chromium, which does not qualify it as stainless steel and, hence poor corrosion resistance.
If you purchase knives made from this steel, have in mind that it is prone to rust, and you should put in a lot of effort to keep it rust-free.
Ensure that the knives are washed and dried after use, and you can apply a coat of oil to keep the rust away.
Sharpening 8670 Steel
Hard steel is challenging to sharpen, but it is not the case with 8670 because it is not very hard.
You can achieve an edge faster using simple sharpening tools. In addition to being easy to sharpen, it holds an edge for a decent time.
8670 Equivalent Steels
8670 Steel vs 1095
1095 steel is more prevalent in the knife-making industry than 8670. You can easily find knives made with 1095 steel than 8670. But 8670 offers better toughness and edge holding ability.
8670 vs 80CrV2
These two steels are very similar in properties and offer excellent edge retention and toughness. Also, they are mostly used in making saw blades. The choice between knives made from these two steels is majorly based on preference and availability but 8670 steel offers better toughness than 80CrV2 steel.
Is 8670 Steel Good for Knives?
Although not popularly used for mass knife production, 8670 steel is a good choice for knife making because it offers excellent toughness.
At a hardness of more than 59 HRC, it ranks high in toughness over other steels. The major downside is the poor corrosion resistance, which can be mitigated by cleaning and oiling.
I would personally recommend other steel like CPM S30V and S35VN over 8670 steel for knives as they offer a great balance of edge holding, toughness, and corrosion resistance.