Knife users have different tastes when it comes to knife material. Blade steel is one particular material where different users part ways. Some prefer low-end steels for their cheap cost, others prefer mid-end steels. Yet some only do the super-steels.
If you fall in the latter category of high-end steels, K390 is one of the steels you'll likely find in your search for the best high-end steel knife. The steel is widely used by reputable brands like Spyderco for some of their blades, like the highly popular Police model.
But does this steel offer features that you desire in a perfect knife for you? How tough is it? For how long does it hold a sharp edge? Is it corrosion-free? Is it even good steel for knives? Let's find out in our in-depth k390 steel review below.
What is K390 Steel?
K390 is advanced cold work steel manufactured by Bohler. The manufacturer utilizes its proprietary MicroClean Technology (or particle metallurgy process) to create this sophisticated alloy mix, enabling it to deliver high compressive strength and extreme wear resistance required in industrial punching, blanking, and cutting operations.
Its fine, homogenous structure makes it easily machinable and heat-treatable. When used in a knife blade, these qualities translate to excellent strength and outstanding edge retention.
Is K390 stainless? No. The material contains less than 13% chromium, which is the threshold chromium level needed to qualify it as stainless steel.
A K390 steel equivalent is S90V since they offer similar characteristics like high hardness, great edge retention, excellent toughness, and so on, due to the high amounts of Vanadium (9%) in both steels. The two steels also fall in the price range, with the only difference setting them apart being that S90V is stainless due to higher chromium levels.
K390 steel composition
Study this k390 steel chart showing the elements that come together to create the k390 steel alloy:
Element | Composition (%) |
Carbon | 2.47 |
Chromium | 4.20 |
Molybdenum | 3.80 |
Manganese | 0.40 |
Silicon | 0.55 |
Vanadium | 9.00 |
Cobalt | 2.00 |
Tungsten | 1.00 |
2.47% Carbon improves steel hardness and wear/corrosion resistance.
4.25% Chromium helps improve the steel tensile strength and edge retention. It also enhances steel corrosion and wear resistance.
3.8% Molybdenum increases the k390 strength and machinability.
9% Vanadium improves the hardenability and wear resistance of this steel.
1% Tungsten improves hardness and wear resistance.
0.55% Silicon improves steel strength.
0.4% Manganese increase hardness and brittleness.
2% Cobalt amplifies the effect of each of the above elements.
K390 properties
What is k390 steel hardness?
K390 hardness is 64-65 HRC, which gives it the tag of very hard steel. Though this might seem on the lower side than what you get with higher-end steels like Maxamet (67-68HRC), it still offers great wear resistance, which makes it suitable for making high-quality knives.
Edge retention
One of the highlights of k390 steel is the ability to holds its edge for longer. This is expected of any hard steel with high Carbon and vanadium content, which results in huge volumes of vanadium carbides. The direct effect of this is increased edge durability, enabling a k390 steel blade to hold its cutting edge better and for longer.
Wear resistance
This Bohler steel has terrific wear resistance, thanks to the high vanadium content in its alloying mix. This means K390 steel won't easily deteriorate and will last for years to come.
K390 rust/corrosion resistance
As we have already stated before, K390 is not stainless because it doesn't contain 13% chromium, the average content required to make it stainless. However, the 4.25% chromium it carries offers some considerable degree of corrosion-resistant. But giving your K390 steel good care is the secret to keeping off corrosion and rust. So, if you're looking for stainless steel, K390 is not for you.
Toughness
The harder the material, the less its capabilities to resist impacts and lateral forces are. This is the case we're looking at in K390 steel. It features high hardness, which makes it less tough. But don't get it wrong; K390 still has decent toughness to withstand most tough cutting jobs. However, you'd not want to use your knife for tougher jobs like batoning unless you want to see it break suddenly or deform and send you back to the stores for a new blade.
Machinability
Another highlight of this steel is good machinability. It contains uniform mechanical properties, which go a long way in making it much easier to work with than most steels out there. This explains why knife smiths favor this steel for knife making. Bohler, the manufacturer behind this steel, even lists "Good machinability" as one of its top benefits.
Sharpenability
Unfortunately, K390 isn't easy to sharpen. This is because of the high hardness it registers on Rockwell Hardness Chart. But that doesn't mean you won't be able to sharpen it again after it gets dull. With more advanced sharpening systems being ushered into the market, you'll get to give your 390 steel knife a super-sharp apex. The only issue is that it might take you longer to sharpen compared to the less hard steels.
k390 steel comparison with other steels
Are you wondering how K390 steel compares with other popular blade steels in attributes like wear resistance, toughness, edge retention, corrosion resistance, and ease of sharpening? If yes, this is your part.
K390 steel Vs VG10
VG10 has better corrosion resistance, toughness, and easy sharpening experience than K390. But K390 beats VG10 with higher corrosion resistance and better edge retention.
K390 steel Vs M390
K390 performs better than M390 in terms of edge retention and wear resistance. M390 compensates for this by being tougher, more corrosion resistant, and easier to sharpen.
Is the K390 good knife steel?
K390 is a good steel for blades because it will cut for longer and keep its good cutting edge. It also comes at a greater working hardness and has greater carbide volume, making it stronger and more wear-resistant.
But the tradeoff is that it will rust easily because it's not stainless. However, good care and maintenance will shield it from corrosion and keep it in good shape. Also, the 390 steel knives come at a higher price due to their great quality.
Overall, this is a great steel for making EDC knives. Top brands like Spyderco use this steel for their top-end blades like Police 4 and Military, which means this is a great steel.
Best K390 Steel Knives:
1. Spyderco Ladybug 3 Lightweight Folding Knife
This is one of Spyderco's smallest and lightest knives designed to be a game-changer in the everyday carry world. It weighs as light as 0.6oz and features a total length of 4.41-inch. It is so small that it easily attaches to your keychain. The knife is as small as your car keys. Get the picture?
The knife qualifies for a spot on this list because it features a high-end K390 steel blade, which offers you exceptional edge retention and wear resistance. It comes in a clip-point blade shape, and just like its larger counterparts, it will provide you with a tremendous cutting performance for fine and heavy cutting jobs.
A super lightweight blue fiberglass reinforced handle comes with this knife. And its bi-directional texturing offers you a secure, slip-free grip.
Because of the extremely small size of this knife, it's clip-less as it's meant for carrying on your keychain or with a lanyard threaded through the hole on the handle's end.
If you're looking for a small pocket knife to add to your collection, this Spyderco Ladybug is worth it. It easily fits your keyring, making it the perfect option if carrying a large pocket knife isn't possible. Though small, the blade has a powerful performance and has an overall quality feel. It simply won't disappoint you.
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2. Spyderco Delica 4 Lightweight Folding Knife
Spyderco seems to be dominating the market with their K390 steel pocket knives. This is another great EDC folding knife from the manufacturer and is designed to offer you reliable, high performance.
It features a superior 2.9-inch k390 steel blade with a flat saber-ground grind for optimal cutting power. It also features a strong, sharp tip, which gives it incredible piercing power. This blade comes super-sharp out of the box, just like the other Spydercos.
The knife features a durable blue fiberglass reinforced handle with bi-directional texturing to offer you great traction and a secure grip in various conditions. If you were to open this handle, you'd discover dual skeletonized steel liners While help strengthen the knife while keeping the weight low.
You'll discover a slip-resistant jimping along the blade's spine, which ensures your safety when using this knife. Phosphor washers have been used in this knife's action to help smoothen out the blade opening and closing.
Don't forget, a reversible pocket clip is included to offer you versatile carrying options for your knife. The knife has an overall length of 7.15 inches plus an overall lightweight design to ensure an easy and comfortable carry.
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Final Verdict
K390 is a really good steel for making knife blades. Its strengths lie in the ability to hold an incredible edge, hold up to cutting tough objects, and superb wear resistance, unlike most of the non-stainless steels available. The major drawback of this steel is high rust vulnerability, which you can easily prevent by taking good care of your knife. If you're looking for the perfect daily carry blade, consider a K390 knife today.