K490

[attila.]

Andre,

Where do you purchase yours from? I'd guess that you aren't in the USA, but I have to ask.

I've been begging steel suppliers to carry this steel in thin sections, but haven't gotten any helpful responses. I contacted Bohler directly and was told that their USA mill can get me a minimum of a 2"x11.9"x12" piece, but without a way to efficiently cut it or an established client base, I can't justify a $2400 minimum purchase.

Thanks!

 

[DeadboxHero]

I know i am necro-threading...

But i find this is the second reference to k490 in knifemaking i have found except my stuff...
I've used it a bit the last year or two and find it very very good, my edc's i can have an edge at 7dps RC63... it gets minor roughness feeling damage doing things like hard whittling and cutting stuff with hard bits in it... chef's knives... i like it, but stock thickness is a pain. heat treat needs to be worked out for your system, but i am using low aus temps and low temper temps and that 30 min soak time seems about right... and cryo... it is pretty darn tough... It decarbs a lot so beware...

Looks closer to M4 then V4e, Im just interested in the low austenizing temps and tempers, Id be curious to see what M4 can do with that. sounds like your doing a 1950f with a 375f temper? Any cold treatment?

 

[Kon]

What about the corrosion resistance of K490?
Is it comparable to any other better known steel?

 

[dirc]

k490 has 1.4% carbon and only 6.4% chrome... it won't have much corrosion resistance...

the closest I could think of in this range is perhaps something like a2 which has upto 1.05% carbon and upto 5.5% chrome
(a3 is much closer with 1.25% carbon, but hardly used or known in knives)

we would need Larrin to weigh in, but it will be better than pure carbon steel (which has no chrome), but it's only at best half way to where it needs to be to be called 'stainless'

 

[MolokaiRider]

"spring steel" is somewhat of a misnomer. Any steel will function as a spring as long as you don't exceed its yield strength. Spring steel is just a high strength steel that will move without taking a permanent set. People make knives out of car springs.

Strength vs. toughness-
Take a piece of wire and start bending it. At low loads you let go of it and it returns to its original shape. Pull it a little harder and it permanently deforms a little bit. You have exceeded its "yield strength". Pull it even farther and depending on the steel it will eventually break, this is its fracture strength or ultimate strength. The yield strength is easy to experience if you play with a piece of coathanger wire. The range of movement between initial yielding and ultimate fracture is the ductility. Ductility is pretty much what we mean by toughness, it bends a long way before it fractures. You won't fracture a piece of coathanger wire by bending it but you can fracture a higher strength steel that way.

If you test nice clean specimens, toughness has no affect on strength, they are separate things. But in the real world, for things whose shapes are not perfectly clean, toughness becomes more important. Someone mentioned grinding a notch in a file and breaking it easily. This is an example of material strength being compromised by low toughness. Knife blades are not always simple shapes. There are various places in a knife where strength can be compromised by low toughness.

There are numerous ways that toughness can be important to a blade. Some examples-
1) I saw pictures where someone was splitting a log with a blade and partway through the log the wood grain deviated and the blade ended up with a good bend in it. Without enough toughness the blade could break right there.
2) Someone could be putting a good load on their knife and it can yield. With good toughness it bends and doesn't break. They see that the knife is bending a little bit and they stop whatever they are doing but the knife is still intact. If the blade had low toughness it would have fractured right away.
3) Knives with significant defects become handicapped with low toughness steels. Things like sharp corners where the tang meets the blade can lead to early failure if the steel doesn't have enough toughness.
4) Bump a staple while cutting a cardboard box and you can bend a part of the edge. If the steel is low toughness then the edge would just chip. If the steel has good toughness then the edge bends but stays intact, and you can fix it.

Great post.

 

[Larrin]

Hello old thread. K490 is Bohler's answer to Uddeholm's Vanadis 4 Extra (and Crucible CPM-4V). Yes I know Bohler and Uddeholm have the same parent company, don't ask me to explain how that works. The extra chromium may help some with corrosion resistance of K490, but it would still be in the non-stainless tool steel category, meaning better corrosion resistance than low alloy steels like 1095 and O1 but much worse than stainless steels.

 

[OrangeBlueOrangeBlue]

Hello old thread. K490 is Bohler's answer to Uddeholm's Vanadis 4 Extra (and Crucible CPM-4V). Yes I know Bohler and Uddeholm have the same parent company, don't ask me to explain how that works. The extra chromium may help some with corrosion resistance of K490, but it would still be in the non-stainless tool steel category, meaning better corrosion resistance than low alloy steels like 1095 and O1 but much worse than stainless steels.

This is entirely speculative, but I'd guess it has something to do with needing to maintain competition to comply with European anti-trust laws.

 

[phm14]

Just ordered the new Lionsteel T6, released in K490. I notice this is the only knife listed in this steel, on the BHQ site. Description copied from the GPK site:

"Bohler K490: Similar in composition to CPM 4V and Vanadis 4E (V4E), K490 is a particle metallurgy tool steel with high toughness (>CPM-M4) and D2 level edge retention. High toughness allows for a thinner, higher performance edge. K490 has added tungsten for increased hardness and wear resistance. Requires care to prevent corrosion."

I chose the "Old Black" tumbled PVD, since some corrosion will be likely at some point. Lionsteel has a nice kydex sheath included, which may be preferable to the leather T5 sheath, which is one of my favorite mid-sized fixed blades. The on point info is much appreciated. Thanks & happy Memorial Day.

 

[dirc]

noticed that lionsteel t6 also, looks very interesting... the modern carbon steel on steroids (would love to see this used in some traditionals)

the only more interesting carbon steel is apexultra which is Larrin s 2nd new steel for the knifeworld

ApexUltra | High performance knife steel for bladesmiths

It is a steel truly worth of handcrafted knives. It is a low alloy design that is forgeable, forge-weldable and its fine carbides make the steel comparably easy to finish and sharpen. With its high purity and well-balanced alloy composition it has the best toughness of all steels tested so far...

www.apexultrasteel.com

 

[skmo]

Just ordered the new Lionsteel T6, released in K490. I notice this is the only knife listed in this steel, on the BHQ site. Description copied from the GPK site:

"Bohler K490: Similar in composition to CPM 4V and Vanadis 4E (V4E), K490 is a particle metallurgy tool steel with high toughness (>CPM-M4) and D2 level edge retention. High toughness allows for a thinner, higher performance edge. K490 has added tungsten for increased hardness and wear resistance. Requires care to prevent corrosion."

I chose the "Old Black" tumbled PVD, since some corrosion will be likely at some point. Lionsteel has a nice kydex sheath included, which may be preferable to the leather T5 sheath, which is one of my favorite mid-sized fixed blades. The on point info is much appreciated. Thanks & happy Memorial Day.

I saw that T6 with natural Micarta and the blackened blade, I almost ordered it on the spot. Then I remembered my new Demko just arrived today, and I don't want to have that wife talk just yet. Please give us a full report.

 

[Dav1]

Someone said k490 is much less tough than 3v this is incorrect. Now I've not looked at the respective data sheets for some time from Carpenter and Bohler but at 58hrc iirc 3v is around 112 ftlb, K490 at its optimum heat treat hrc of 61-62 is iirc circa 82 ftlb. Bring the 3v up to 60 or beyond and K490 is "tougher" and better edge retention so in theory a great steel.

 

[Larrin]

Someone said k490 is much less tough than 3v this is incorrect. Now I've not looked at the respective data sheets for some time from Carpenter and Bohler but at 58hrc iirc 3v is around 112 ftlb, K490 at its optimum heat treat hrc of 61-62 is iirc circa 82 ftlb. Bring the 3v up to 60 or beyond and K490 is "tougher" and better edge retention so in theory a great steel.

Crucible and Bohler do not use the same toughness test so their numbers cannot be compared.

 

[LimpCroissant]

Excited to see what happens with your ApexUltra steel Larrin! Magnacut sure has taken off.

That's pretty awesome that Lionsteel made a knife in K490. If I didn't already spend too much on knives lately I would have loved to get one too.

 

[Dav1]

Bohler class it as an high toughness tool steel its in the 7% chrome tool steel class. Bohler also compare it to M4 toughness circa 2.25 - 2.5 times as tough. Which puts it within the figures I stated compared to 3v using Larrins charts.

It's a tough tool steel not far behind 3v with better edge retention. It's a very interesting steel. I'll be buying the T6 will hard use against my 3v blades, so we shall see.

 

[skmo]

Crucible and Bohler do not use the same toughness test so their numbers cannot be compared.

I just saw your picture on the Apex Ultra page. What's the deal, are you 12? Man, for someone as young as you are, you are definitely an all-star in the world of steel. No worries about Crom kicking you out of Valhalla because you don't know the Riddle of Steel. I presume Golden, CO is as beautiful as it was when I grew up near there.