In this article, we'll tell you all you need to know about AR-RPM9 Powder Steel blades found on EDC knives.
What is AR-RPM9 Steel?
AR-RPM9 steel is form of stainless steel manufactured by a well know knives company called Artisan Cutlery.
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This metal is formed using a specialized metallurgy process that contains 9 different elements to form the steel, thus the 9 in the naming of AR-RPM9 steel.
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Artisan Cutlery claims that the AR-RPM9 is a budget steel, but the specialized composition of rare earth elements makes as good of a quality as any higher end steel.
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What is AR-RPM9 Steel Composition?
Artisan Cutlery has revealed most of the AR-RPM9 steel's composition. It has also mentioned that the steel contains RE (rare earth elements), but it did not reveal what these elements were.
It has 0.9% Carbon, 18% Chromium, 1.0% Molybdenum, 0.45% Manganese, 0.1% Vanadium, 0.30% Cobalt, 0.2-0.8% Silicon, and less than 0.40% Nickle.
AR-RPM9 Steel Toughness
The toughness of steel is the steel's ability to absorb impact without fracturing.
With that being said, due to it's high hardness, the AR-RPM9 steel has lower toughness levels. This makes it very brittle and it can fracture easily.
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AR-RPM9 Steel Hardness
AR-RPM9 powder steel has a hardness of 58-60HRC on the Rockwell hardness scale.
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This is high hardness expected to be found in higher end higher quality knives such as those from brands like Spyderco, but many more brands are starting to use AR-RPM9 steel.
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Just like the 9Cr18MoV steel the higher hardness contributed to the high carbon content and the presence of vanadium and cobalt.
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Higher steel hardness will give you better edge retention. Your blade will remain sharper longer.
Measuring Steel's Hardness Rockwell Scale!
AR-RPM9 Steel Corrosion Resistance
AR-RPM9 is stainless steel thanks to the it's higher chromium content. Any metals that contain a higher chromium content will be considered stainless steel metals.
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Stainless steel should will have at least 12% chromium content.
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Generally, most AR-RPM9 steel will have higher corrosion resistance and can be use safely in highly corrosive environments, but with good maintenance (cleaning the knife often).
AR-RPM9 Steel Edge Retention (Sharpness)
The edge retention of steel is directly related to it's hardness and toughness. With a high hardness of 58-60HRC, AR-RPM9 steel blades will hold an edge for a long time.
AR-RPM9 Steel Ease of Sharpening
With a higher hardness AR-RPM9 is steel that's going to be harder to sharpen. The blade will maintain sharp edge longer, but you will spend a bit more time sharpening the AR-RPM9 steel blade.
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Due to it's brittle nature, it will have to be honed during the sharpening process. Learn more about honing.
Popular AR-RPM9 Steel Brand Knives
The most popular brand of AR-RPM9 steel knives is the Spyderco and CJRB.
Is AR-RPM9 Steel Good for Knives?
We can confidently conclude that powder AR-RPM9 steel is good budget steel that's great for knives. Again, this type of steel is consider higher end budget steel.
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Overall, it offers high hardness, good edge retention, good wear resistance, excellent corrosion resistance, and fair toughness.
In comparison to other metals, AR-RPM9 steel knives compare equally to the 9Cr18MoV steel knives, which has the same hardness 58-60HRC.
Final Thoughts
AR-RPM9 stainless steel is a great choice for pocket knives. What makes it great is corrosion resistance, high hardness, great edge retention, great corrosion resistance, and good toughness.
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Best of all, AR-RPM9 steel blades are considered to be high-end budget knives. So, if you looking for a good quality knife for a lower price, AR-RPM9 steel knives are a great choice.