OKC's SP series 1095 switch to 1075 steel...

[PocketKnifeJimmy]

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

 

[Roguer]

Yep.

I figure the Experted Ones know what they are doing, I got several of their SP+ knives knowing of the 1075 shift where they got a better more affordable steel for they way people like me put their tools through.

 

[dingy]

i love tough knife

 

[flatface77]

Is there a way to tell by looking? Did the change come with the gold laser etching?

For knives that need toughness this is a great move. You & Dan are encouraged to bore us with the metallurgical mumbo jumbo. I'm still learning, but less excess carbon in these 1075 blades that end up in the mid-to high 50s Rc means less martensite to weaken them, right?

 

[dingy]

i really wish okc will produce sp10 made of 5160.

 

[Toooj]

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

 

[bikerector]

Hi Tooj, I'm curious if 1084 was investigated as an option. It seems like that has a fair amount of springiness and a little more carbon than 1075, though maybe not enough to make a difference and probably harder to come by.

Having had 1095 and 1075 in big knives, I can certainly agree you can beat the snot out of 1075. I have two condor machetes, golok and viking, and have broken the handles from the shock of hitting frozen branches from clearing up trails this winter but the steel didn't blink and I was actually surprised at how well the edge held. I should add though, the kabar becker knives in the modified 1095 take a beating pretty well too though I haven't been as hard on them as I have on my golok, simply a lot more leverage on that one.

I have recently started becoming a fan of some of the lower carbon steels, like sandvik and AEB-L. Seems like they stay sharp because of the fine edge you can put on them but have oodles of toughness. I've really been looking into having a forum maker put together a chopper or machete in AEB-L or similar for some of the winter trail work since the ice formation on the blade can cause considerable rust issues unless I watch the ice melt off and get the oil on it fast.

 

[Toooj]

bikerector,

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

 

[bikerector]

bikerector,

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

Don't forget rust-proof, takes on a mirror polish and can be used in a damascus pattern. Gotta think of those aesthetics.

Appreciate the incite Paul. Getting some realistic tips from the pros is always nice; helps bring us "why can't it do this too" level of needy patrons back down to Earth.

 

[Roguer]

Wow!

Thanks for the in depth reasoning of what and why such steels are used and even a different manufacture I happen to got a few other knives from to cover my needs.

Affordability and reliable hard use tools is why I keep going back to Ontario, and the affordability lets me get more than one for uses to use. And some thing I can trust for some one else to use and trust their life on it if needed when I loan/gift/letthemstealit one out. That's the store I put in most OKC products.

 

[Revolverrodger]

How do I know if my sp10 is 1095 vs 1075?
Thanks

 

[Toooj]

Revolverrodger,

Good question. We switched over around 2-2-1/2 years ago so if your SP-10 purchase was prior: 1095. If during the last couple of years: It could be either.
Dan Maragni and I will think about how to easily tell them apart.
There may not be a easy answer.

Best Regards,

Paul Tsujimoto
V.P. of Engineering
Ontario Knife Company

 

[bikerector]

I think everything on the OKC website still says 1095, not that I stalk the website frequently looking for new things I don't need but want. Actually, I think I spend a lot of time trying to figure out if you have something new in D2 coming out since I've had a lot of enjoyment from my modified TAK-1 in D2 (blade regrind to thin it down).

 

[buckfynn]

Oh yes the great euticoid vs hypereuticoid debate. 1075 being near euticoid and 1095 being hypereuticoid. Retained austinite being one of the issues with 1095 if not properly tempered.

Still I am not convinced the move to 1075 from 1095 is "better" as there is always going to be trade offs in the end results. 1075 will be tougher, but I doubt it will have the same edge retaining ability as 1095. And there lies one of the trade offs.

 

[Yonose]

I think everything on the OKC website still says 1095, not that I stalk the website frequently looking for new things I don't need but want. Actually, I think I spend a lot of time trying to figure out if you have something new in D2 coming out since I've had a lot of enjoyment from my modified TAK-1 in D2 (blade regrind to thin it down).

Was this the one with partial serrations originally? I see one website stil has them in d2 listed for sale, at $97. I love the tak mod they made in 154cm and it was even cheaper.

 

[Yonose]

Oh yes the great euticoid vs hypereuticoid debate. 1075 being near euticoid and 1095 being hypereuticoid. Retained austinite being one of the issues with 1095 if not properly tempered.

Still I am not convinced the move to 1075 from 1095 is "better" as there is always going to be trade offs in the end results. 1075 will be tougher, but I doubt it will have the same edge retaining ability as 1095. And there lies one of the trade offs.

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.

 

[bikerector]

Was this the one with partial serrations originally? I see one website stil has them listed for sale. I love the tak mod they made in 154cm and it was even cheaper.

No, I think this may have been one of the original designs. I got it used and we were unable to figure out age and such based on the handle, and I'm not sure if that is original or not. I know the newer ones have been 1095 for quite a while now. Can't remember the last time I've actually sharpened that thing. Not a razor but it still pushes through wood and vines well when cleaning up riff-raff around the yard. Darn wild grape vines are a constant battle and I see more in the backwoods i need to take care of when this heat wave stops.

OKC has done well with the value of their knives, especially if you plan to use them and the handle shape works for you. The tak is amazing compared to the rat 5 I used to have, which was a bit big for my hands after an hour or so of use but that was probably more durable too.

 

[Yonose]

No, I think this may have been one of the original designs. I got it used and we were unable to figure out age and such based on the handle, and I'm not sure if that is original or not. I know the newer ones have been 1095 for quite a while now. Can't remember the last time I've actually sharpened that thing. Not a razor but it still pushes through wood and vines well when cleaning up riff-raff around the yard. Darn wild grape vines are a constant battle and I see more in the backwoods i need to take care of when this heat wave stops.

OKC has done well with the value of their knives, especially if you plan to use them and the handle shape works for you. The tak is amazing compared to the rat 5 I used to have, which was a bit big for my hands after an hour or so of use but that was probably more durable too.

I think you can still get one in d2, but it’s partially serrated and costs close to $100. Yours has , walnut handles? Wasn’t sure if they were custom or not.

 

[bikerector]

I think you can still get one in d2, but it’s partially serrated and costs close to $100. Yours has , walnut handles? Wasn’t sure if they were custom or not.

Spalted maple I think, I forget but keep the email for when I want to remember. They're pretty nice looking but can be slippery.

 

[Yonose]

Spalted maple I think, I forget but keep the email for when I want to remember. They're pretty nice looking but can be slippery.

I thought it was light for walnut, but I only remember Ontario using walnut, such as the limited rat3–which was also in d2 steel, and came with a thick leather sheath. Ontario makes some really cool and affordable limited editions, which if you blink you could easily miss.