Serious question, what make steel tough??

K

KyKaMo

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Mar 31, 2012
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Perhaps this question looks stupid, but Im trying to figure out how you can look at a steels composition on know that it's tough?

For instance, how is a 1095 steel tougher than 440c? Is it because iron is really tough, so the less alloys the tougher? Or is it because chrome helps hardenability and that stiffens the steel making it less tough (and 440c has more carbon)?

Im wondering, because I was looking at trying a buck marksman in 154cm because I heard it was a tough steel, but then also heard of 154cm knives chipping alot. I thought a tough blade shouldn't chip as much? And isn't molybdenum suppose to make a steel tougher? But isnt it also a strong carbide former, making the steel more brittle? I'm confused as to how tough 154cm really is
 
I am not sure where you "heard" a lot of these things?

I can tell you that 154CM/CPM154 has many traits, and HT being done right, one of them is not chipping.

I have used it more than any other steel, harder than any other steel, and at angles as low as 15DPS.

I can't answer "what makes a steel tough"

I look at the composition of many of the steels available today, and I am amazed by how some steels that seem like they would be "tough" aren't, and vice versa.
I imagine it's an obvious combination of material composition and HT process.
 
Toughness is best appreciated in a knife that will see a lot of chopping, such as a fixed blade. Typically, a lower amount of carbon will increase toughness. Pure carbon (diamonds) are very hard, but very brittle and this trait follows through with steel with a high carbon content. Lower amounts of carbon allow irons ductility to be appreciated:thumbup:

Although, as JDM said, overall chemistry and heat treat will have a large impact too. My above sentiment is only the tip of the iceberg:)
 
There is toughness and then there is perceived toughness. What most people talk about in knives they use is perceived toughness. Perceived toughness takes into account not just the steel composition, but crappy HT or supercharged HT. It also takes into account blade geometry and edge geometry as well as Rc. Take two ontario knives for example. The machete bowie which is flat ground 1/4" stock and the marine raider bowie which is low sabre grind 1/4" stock. Toughness should be identical in the steel. But the marine raider's blade geometry makes for a much tougher overall knife at the expense of cutting geometry. Many custom makes have made tough knives in this way out of steels you do not consider tough, like 440C. Make it a sabre ground blade at an Rc of 55-56 and the toughness will feel high.

Back in the 90's Camilus made a heavy machete for United knives out of ATS-34. That knife was tough as nails. I beat the crap out of one for years. It had a tough blade geometry, slightly lower hardness than normal, good steel and good HT. The entire combo worked.

hope that helped a little
 
Stainless steel actually has a softness to it pre and post heat treatment...it just depends on the grade of stainless,the lower the grade the softer it is.Yes these steels harden but alloying prevents them from getting hard as tool steel.1095 is a complete different story because it's a tool steel and not alloyed like stainless steel.Heat treating a plain piece of tool steel will take on a very hard state.You'll notice when you sharpen stainless and tool steels they have completely different characteristics in sharpness.

High amounts of molybdenum like the 4.00% content used in ATS-34 and BG-42 actually play a firm role in hard edged stainless steels combined with a good heat treatment.Keep in mind though these steels weren't made for kitchen cutlery...they are industrial steels.They are bearing grade steels so they're meant to resist wearing down at high speed/high friction uses.They are very basic in rust and stain resistance and have a larger priority in edge retention.I've been using ATS-34 on my same pocket folder for 17 years now and to me I think the knife industry had a more logical mindset on what makes a premium steel versus brittle stuff like VG-10 and S30V which only seem to prove their worth in cutting natural materials...anything hard they chip easily.Yes ATS-34 is a late 90's super steel but I think it's excellent...definitely challenges the newer steels of today regardless of it's 1.05% in carbon.And high amounts of molybdenum do separate a soft razor stainless from one built to cut quite a bit of material.

No offense intended but I can't speak for 154CM as an American made steel because American knife companies turned to Hitachi Metals for ATS-34 as Crucible kept botching the 154CM while Japan knew how to make it properly.Then the ATS-34 took criticism in the early 2000's because it was a foreign steel and people were whining for American made premium steel.Then (finger snap) bingo all of a sudden 154CM is back in the knife industry and claimed to be cleaned up,ATS-34 took a nosedive in reputation and got fitted in Crucible's old shoes on inconsistency.I'd rather reach for ATS-34 primarily because something is sketchy with Crucible.If the 154CM is supposedly perfect now then why would they make a particle metallurgy version of it called CPM 154.
 
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Look up zknives.com and get the application. It will help you in your quest for knowledge of steel.
Russ
 
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