The BladeForums.com 2024 Traditional Knife is ready to order! See this thread for details:
https://www.bladeforums.com/threads/bladeforums-2024-traditional-knife.2003187/
Price is $300 ea (shipped within CONUS). If you live outside the US, I will contact you after your order for extra shipping charges.
Order here: https://www.bladeforums.com/help/2024-traditional/ - Order as many as you like, we have plenty.
I hope you realize that 5160 = 0.6% carbon... so it's similar to 1060, but with a tiny tiny bit of chrome added (not for rust resistance)
Also, 1095 = 0.95% carbon...
so why is 1075 (with 0.75% carbon) so scary? I know it's not as popular as 5160, which recently has a resurgence of popularity, but so what?
IMHO 1075 is a nearly perfect low cost carbon chopper steel, tough tough stuff. My preference would be 80crv2 of course.
flatface77,
Okay you asked for it.In a nutshell (and I am not a professional metallurgist. I just play one at work)
Martensite has two different formations: in steel around .60-.78% carbon, the Martensite is called Lathe Martensite. In steel around .90-1.0% carbon, the Martensite turns into a structure called plate Martensite.
This plate Martensite stacks up like...plates. When stressed, the plates will deform and slide against the other plates and eventually separate which causes cracks and chipping, etc. The lathe Martensite bonds differently and has a different structure which is less prone to slippage along the molecular structure. That is the first reason for Ontario moving to a lower carbon content.
Another reason is that in steel only .56% of the carbon goes into solution with the iron forming steel. The rest of the free carbon attaches to other alloys forming carbides. Some of these carbides are excellent to have and others not so much. Most carbides are harder than the Martensite matrix and will offer enhanced cutting ability but because they are harder, have a tendency to chip out of the Martensite if impacted. This is subjective but with 1095 there is much more free carbon to form pretty large carbide strings and conversely more chance for chipping/cracking along the cantle.
Lastly, during the Austenite to Martensite transformation, not all of the austenite transforms leaving retained austenite in the martensitic structure. This is not good. Austenite is softer than Martensite and when randomly strung through the Martensite allows a hard/soft interface to occur. This interface is the starting focal point of many stress risers that will eventually lead to cracks and deformation. If equally and properly heat treated, 1075 will have a lower percentage of retained austenite than 1095.
So there you go. I am sure there will be some conversation, some heated, about this but we have already started to see the results...and it is better.
I hope this helps.
Best Regards,
Paul Tsujimoto
V.P. of Engineering
Ontario Knife Company
The switch to 1075 carbon steel from 1095 carbon steel on the majority of the OKC SP series, (non Gen2), is said to have been done 2-3 years ago. The following is a post put up by Paul Tsujimoto (Toooj) recently on this forum. It gives a short bit of insight into why the decision to switch was made. This is not being put up by me to debate the pros and cons of their decision, but only to share the info again so that folks that had not read this before, can now be informed about it...
We do a lot of metallurgical testing and review concerning the type of steel and properties and how it relates to quality issues. We have come to the conclusion that 1075 is a better steel for the vast majority of our knives. 1075 still has sufficient carbon to produce a nicely hardened blade, it has good edge retention and it also has a lot more toughness to hold up to the impact that working knives (machetes) see on a continued basis. That is the reason for the change. Our Military contract knives still will use 1095 but any knife/tool that is not under specification has been changed to 1075. I think you will find a lot less chipping and breakage with the 1075 steel. Dan Maragni and I could bore you with Metallurgical mumbo-Jumbo but ultimately we like not having to deal with broken blades under warranty and we think you will also.
Hope this helps.
Best Regards,
Paul Tsujimoto
V.P. of Engineering
Ontario Knife Comapany
flatface77,
Okay you asked for it.In a nutshell (and I am not a professional metallurgist. I just play one at work)
Martensite has two different formations: in steel around .60-.78% carbon, the Martensite is called Lathe Martensite. In steel around .90-1.0% carbon, the Martensite turns into a structure called plate Martensite.
This plate Martensite stacks up like...plates. When stressed, the plates will deform and slide against the other plates and eventually separate which causes cracks and chipping, etc. The lathe Martensite bonds differently and has a different structure which is less prone to slippage along the molecular structure. That is the first reason for Ontario moving to a lower carbon content.
Another reason is that in steel only .56% of the carbon goes into solution with the iron forming steel. The rest of the free carbon attaches to other alloys forming carbides. Some of these carbides are excellent to have and others not so much. Most carbides are harder than the Martensite matrix and will offer enhanced cutting ability but because they are harder, have a tendency to chip out of the Martensite if impacted. This is subjective but with 1095 there is much more free carbon to form pretty large carbide strings and conversely more chance for chipping/cracking along the cantle.
Lastly, during the Austenite to Martensite transformation, not all of the austenite transforms leaving retained austenite in the martensitic structure. This is not good. Austenite is softer than Martensite and when randomly strung through the Martensite allows a hard/soft interface to occur. This interface is the starting focal point of many stress risers that will eventually lead to cracks and deformation. If equally and properly heat treated, 1075 will have a lower percentage of retained austenite than 1095.
So there you go. I am sure there will be some conversation, some heated, about this but we have already started to see the results...and it is better.
I hope this helps.
Best Regards,
Paul Tsujimoto
V.P. of Engineering
Ontario Knife Company
Sorry but Unobtainium has been used already LoLbikerector,
We investigated 1084. The problem was that the steels between 1075 and 1095 have a mixture of Lathe and Plate Martensite. We felt it was best to move away from any Plate Martensite altogether, hence the use of 1075. While we are open to new processes and materials, we have to be good stewards with the company money.
I understand your love of 1095CV at KA-BAR. I spent many years there and think it's a great steel. The small amounts of Chrome and Vanadium make for some of the good carbides I was talking about.
KA-BAR marquenches their steel to maximize toughness and reduce chipping. While that HT protocol is exceptional, Ontario is presently not prepared to go in that direction. (Maybe in the future)
AEB-L is an excellent steel and we are pondering it's use in a new kitchen knife line. It is a low alloy, clean steel. IMHO, that is why it is a good knife steel. There are only a few carbides to mess up the edge.
Many of the newer knife steels are trying to replace some of the carbon with nitrogen or other interstitial alloying element. Carbon in steel is a double edged (please excuse the pun) boogieman. For every good point, there is a bad point. Just about everything we do is a balancing act. We are always trading off a characteristic or property with another to achieve a desired result.
I have spoken about this in the past: Whoever comes up with the following material will be the richest person in the world. It must be infinitely hard, infinitely tough, infinitely strong, infinitely light, infinitely rigid, infinitely flexible...it will be called: Unobtainium. LOL.
Hope this helps.
Best Regards,
Paul Tsujimoto
V.P. of Engineering
Ontario Knife Company
FileZilla Malwarebytes RufusI would ask tooj on that one, since all descriptions I’ve seen the last several years on the sp-10 have shown it being 1095 as well. I believe he said all 1095 blades not produced under military contract are now being made from 1075. They are looking for ways to distinguish on a case by case basis.
I would like to by the original 1095 machete, I think it’s 18” blade has a 44 as the last letters of its catalog listing, but I know they make a lot of different machetes, which are now 1075.
FileZilla Malwarebytes Rufus
Tooj said that it was really their only option, not having marquenching ability on site—which sounds like a complicated and thus expensive operation. Had they this ability, 1095 would definitely be a better option. Even those break more frequently ime than 1075.
Mar quenching as I understand it is basically a salt water bath (after heat treat). If I’m not mistaken some of the nitrate in the salt enhances the toughness, if done in small batches. If they make knives for military, and have a huge new facility—my question is “why don’t they”— my hypothetical answer is that they make so many knives (at prices and quantities?) that it doesn’t make fiscal sense. Kabars cost $30 approximately per knife. Well treated 1095 will almosth never break and hold an edge longer. But tooj and you are correct about 1075. It just needs more frequent sharpening. 5160 won’t break at all ime. I do own a sp10 in both steels, and the 1095 cuts wood like butter while the 1075 lags far behind in performance. Some of the money saved goes toward a better edge, I think.