Why does O-1 steel rust easier than SK5?

[BluntCut MetalWorks]

ime

When ht tinkering low/no Cr steels, I use overly prone to rust/corrosion as indicator of botched ht. I can confirmed for most of these botched cases using a lighted microscope (polished and etched samples) - often matrix microstructure has excess dislocation/stress from combination of large grain and high % of plate martensite. Translate to more gaps to trap & migrating corrosive agents.

https://www.researchgate.net/public...teel_and_the_effects_on_mechanical_properties

If you look at O1 ht literature, noted carefully/caution worded on quench cooling speed, especially between Ms (mart start) and room temperature. Well maybe some observed O1 eager to rust perhaps because there are higher proportion percent of poor and botched O1 ht blades out there vs other carbon steels.

 

[Yonose]

I can only guess people who don't worry about rust on carbon steels have never used their knives while it rained heavily with no shelter... My 5160 knife, a low carbon steel, was severely pitted with hundreds of orange spots throughout its 11" blade in less than two hours... The leather sheath in which this happened hardly noticed, and I hate leather because it usually goes soft like a noodle in real wet conditions...

And no, I could not wipe the blade dry before sheathing, because it was raining, remember? Like I said, a good Cerakoat fixed that problem, but obviously a lot of hard core "woodsmen" tend to go out in more ideal conditions...

One thing you do find out is that a really wet log sticks to your blade like it was concrete poured around it, but I'll let the real woodsmen tell you the neat trick to get out of that predicament...

Gaston

It had actually pitted in two hours?! I usually oil my sheathes regularly and haven't ever had pitting. My 5160 blades do tend to slowly patina even when dried and lightly coated with mineral oil, more so than my 1075 blades, but .6 carbon isn't technically "low" unless compared to d2 or super steel

 

[KingMC]

I can only guess people who don't worry about rust on carbon steels have never used their knives while it rained heavily with no shelter... My 5160 knife, a low carbon steel, was severely pitted with hundreds of orange spots throughout its 11" blade in less than two hours... The leather sheath in which this happened hardly noticed, and I hate leather because it usually goes soft like a noodle in real wet conditions...

And no, I could not wipe the blade dry before sheathing, because it was raining, remember? Like I said, a good Cerakoat fixed that problem, but obviously a lot of hard core "woodsmen" tend to go out in more ideal conditions...

One thing you do find out is that a really wet log sticks to your blade like it was concrete poured around it, but I'll let the real woodsmen tell you the neat trick to get out of that predicament...

Gaston

Many of my trips out into the woods involved getting rained on, and using my knives in the rain. Heck, just in the past calendar year I had precipitation on all but one of the camping trips I went on, and I'm not even a 'hard core "woodsmen"' like you so flippantly remarked. I have always had either shelter or a waterproof layer keeping me from getting soaked, because unlike what you described I actually plan for the rain and thus am able to work around whatever weather gets thrown at me. I live in the PNW, rain is inevitable 8 months out of the year, there were 3 times this winter I was out in the snow too, didn't let my knives rust though.

My O1 knife has a great patina and has rarely if ever attained rust even though I keep it in a leather sheath while camping and have used it on all my trips. My 1095 knives have also survived all the trips in their various nylon and kydex sheaths, the only rust I've attained on a camp tool of mine has been on my Hults Bruk axe and that's because it's been stored in a stump overnight, got a light surface coating that was easily cleaned off with the moss laying around, and we moved on.

The effort needed to maintain a rust-free blade is so minimal that even a beginner with little to no experience with carbon blades should be more than able to keep them maintained.

 

[unklfranco]

The effort needed to maintain a rust-free blade is so minimal that even a beginner with little to no experience with carbon blades should be more than able to keep them maintained

+1. Almost a non issue after "minimal effort". The PNW and Florida are brutal when it comes to humidity.

 

[Gaston444]

It was not pitted after five minutes of sanding the rust spots out, but before sanding it definitely looked heavily rusted with surface rust all over in less than two hours.

The Patriot leather sheath had little to do with it: The blade being wet and nearly unwiped was all it took: It would have been a similar story in Kydex... On the contrary, the raw insides on the Patriot leather probably absorbed some moisture away from the steel: Areas of sheath contact friction were almost rust-free...

The sheath was not oiled inside because I hate to see any residues sticking to my blade, which is exactly the reason the Patriot leather maker stated he delivers the sheath with raw insides like this: The leather becomes polished on the contact points, but still takes some moisture away.

Sanding out the rust by hand was quick, but it meant the steel grain finish was no longer even, which I think looks way worse than a lightly scuffed Cerakoat (which can itself be fine-sanded back to a new-like appearance several times over)...

What's more, the 5160 edge itself was rusted enough to be very noticeable in the phonebook paper cutting performance: The edge was quite coarse in less than two hours of wetness...

I think if you look at this objectively, you would know that if stainless had been available in the days of the Frontier, virtually all period knives we would see today would be made of stainless, including Jim Bowie's knives, and probably even most cavalry swords...

Only the luxury we live in today, where you never really have to go out in the rain, even allows people to think of Carbon steels, especially unpainted blades, as still on the same plane as stainless steels... The fact that many people strip their carbon steel blades to the metal just underlines how little harsh weather they actually encounter...

Gaston

 

[KingMC]

I think if you look at this objectively, you would know that if stainless had been available in the days of the Frontier, virtually all period knives we would see today would be made of stainless, including Jim Bowie's knives, and probably even most cavalry swords...

Only the luxury we live in today, where you never really have to go out in the rain, even allows people to think of Carbon steels, especially unpainted blades, as still on the same plane as stainless steels... The fact that many people strip their carbon steel blades to the metal just underlines how little harsh weather they actually encounter...

Gaston

Stainless is hard to manufacture, hard to heat-treat, hard to sharpen, and easy to break. What makes you think that the combination of all those issues would make a stainless knife more appealing than a carbon-steeled blade that's only downside is the ability to rust if not maintained? Only a lazy fool fails to maintain their tools if they use them, so rust is only an issue for the lazy.

 

[GrReaper]

I have a fixed blade in O1 that developed slight surface rust, and a couple small pitting spots. It was a bit odd because the other knives I have in 1095 did not, they were stored in the same container. I don't use anything in terms of oil that will decompose or evaporate. If you use the knife for food prep, mineral oil might be a good idea and wipe the blade before and after use. If not for food prep, you can use something a little heavier duty like motor oil, 3 in 1 oil, etc. Leave a medium heavy coat for a day or so then wipe away the excess. That will help for the most part, just my 2 cents.

Yep, that's what I'm talking about. Strange that O-1 would be that rust prone versus 1095 or SK5. I use mostly 3 in 1 oil for my outdoor knives. For food prep, I only use stainless steel, so no oil necessary there.

 

[GrReaper]

Higher carbon can cause rust, yes. So can differences in heat treats and more so final finishes. When I use my rustable blades outdoors here in NC summers I keep a silicone cloth in a baggie nearby. I wipe it down during the day after use or when needed. It works better for me than oils. When I can I keep the knife cleaned of salts/acids then paste wax. These things take seconds of my time and reduce the problems greatly.

Yes, it must be the differences in heat treats and finish type, probably more so than just the small difference in carbon. I will try the silicone cloths. Thanks!

 

[GrReaper]

I think if you look at this objectively, you would know that if stainless had been available in the days of the Frontier, virtually all period knives we would see today would be made of stainless, including Jim Bowie's knives, and probably even most cavalry swords...

Only the luxury we live in today, where you never really have to go out in the rain, even allows people to think of Carbon steels, especially unpainted blades, as still on the same plane as stainless steels... The fact that many people strip their carbon steel blades to the metal just underlines how little harsh weather they actually encounter...

Gaston

I agree with KingMC above on this point. Most commonly available stainless is still not as good as carbon or tool steel. Definitely not as tough. Unless the budget is unlimited, I think most of us would choose 5160, A2 or 10xx steel for hard outdoor use over some super stainless steel. If the blade is coated, that really helps prevent any rust. You only have to worry about the edge and any places where the coating has worn off.

 

[The Mastiff]

"Yes, it must be the differences in heat treats and finish type, probably more so than just the small difference in carbon. I will try the silicone cloths. Thanks!"

Very welcome Reaper! I learned about those back when I found out how difficult 100 year old Mausers were to keep unrusted here on the range in July. Old corrosive ammo sure didn't help but even without that the old hot blued rifles would have fingerprints etched into the bluing in not long at all. They were tougher to keep free than any knife I've encountered by an order of magnitude. I have probably 7 or 8 O-1 knives and I don't baby them. I do find my trailmaster in SK 5 will last longer but eventually everything not maintained goes.

Joe

 

[Yonose]

New "I can only guess people who don't worry about rust on carbon steels have never used their knives while it rained heavily with no shelter... My 5160 knife, a low carbon steel, was severely pitted with hundreds of orange spots throughout its 11" blade in less than two hours... The leather sheath in which this happened hardly noticed, and I hate leather because it usually goes soft like a noodle in real wet conditions..."

Your sheath didn't notice because it was too busy depositing salts/acids on your knife which combined with the humidity to begin the corrosion. No surprise and certainly no fault of the steel. Leave the pretty hand stitched leather sheath at home.

I suspect your idea of "severely pitted" differs from mine.

Have you thought about going into those conditions with a seal like paste wax on the knife? It wears off obviously in places with use but is more resilient in protecting the steels structure than many think. Naturally one would want a clean and dry surface to wax or oil .Not really smart to just glop stuff on salt still on the blade when you are back at camp or home. Wash the steel off then lube or wax.

Some folks really seem to make this stuff more complicated and worse than it should be. Tools were maintained for centuries with less than we have in much worse conditions. Also, why would my knife be in a wet log except in emergency conditions like a plane crash? I have an axe, maul, whatever I need when I expect to have to use them. Just part of planning and preparation. If you don't have what you need except in very unusual emergencies you have done something wrong. That means camping and bushcraft even when going light. Being an unprepared fool sure isn't my idea of recreation. I've lived, worked or stayed in every climate type our world has to offer. My favorites are arctic and alpine. Least favorite? Pretty much everywhere inland near the equator. Desert isn't that bad though.

Joe

Yeah severe pitting could be fixed by a cerakote. Just curious, what is it you don't like about inland near the equator. One of the most 50 most (imo) beautiful places on earth are the buffs overlooking the Rio Magdalena in southern huila province Colombia! Lush as a Kentucky lawn And only 150 miles from a high desert!

 

[Yonose]

Did OP ever state what was the maker of the knife with the rust problem?

 

[Phydeaux]

I use a couple of 01 knives in the kitchen. As long as I dry them after washing, I have no problem with rust. 01 can impart a slightly different flavor to foods. My family noticed it when I first started using them. Now it formal to them.

Ric

 

[The Mastiff]

"Yeah severe pitting could be fixed by a cerakote. "

Gaston was the one that talked about that. I had just quoted his statement because I wanted to talk about parts of it.

"Just curious, what is it you don't like about inland near the equator. One of the most 50 most (imo) beautiful places on earth are the buffs overlooking the Rio Magdalena in southern huila province Colombia! Lush as a Kentucky lawn And only 150 miles from a high desert!"

I don't dislike it as much as I just don't do as well in those areas. I enjoy beach vacations as well as any person but find the equators tropical environment pretty overwhelming physically. Heck, North Carolina in the summer is bad enough. I'm just more suited to the cooler and colder environments . I've never not ended up being sick from some bug or fungus or parasite in jungle type environments but push me out of a plane over sub artic, or boreal forests even in winter and it's difficult to get me to go home even with the mosquitos there in summer. I was fortunate to live in the Alps and the Rocky mountains and I found that just right too. It must be genetics ( polish/lithuanian heritage). I mean no insult to the areas on the equator. I just find it alien anywhere 100 ft in from the beach when I'm down there. I'm getting too old for those adventures.

Joe

 

[Yonose]

I was agreeing with your interpretation of the pitting he talked about, but left out a modifier!
I thought you might be tired of the 12 hour days down at the equator, didn't think you hated it. The mountainous areas of equatorial South America are a lot more populated than the Rockies, which I love as well, and since I'm mostly European ancestry I stick out like bedsheet down there

 

[Gaston444]

Stainless is hard to manufacture, hard to heat-treat, hard to sharpen, and easy to break. What makes you think that the combination of all those issues would make a stainless knife more appealing than a carbon-steeled blade that's only downside is the ability to rust if not maintained? Only a lazy fool fails to maintain their tools if they use them, so rust is only an issue for the lazy.

Yes heat-treating stainless for 1800s one-man "Frontier" forges probably would have been a challenge...: But most large "quality" knives of the time were English-made in large factories. What probably would have happened is that the English factories would have gotten better and mastered stainless. So you would have local one-man forge production in carbon, and, increasingly as time went on, English imported production in stainless, with superior edge-holding... Given the ease of sharpening, I concede there would probably still be a lot of the cheaper carbon blades about, but they would be considered second rate, especially for quality weapons that sit a lot without being used.

Properly tempered stainless is not easy to break, and you can make swords out of it, just ask Jay Fisher. I have a cheap French Sabatier Jeune Boy Scout knife of the 1940s that is stainless (a fairly large 7" blade): It is not brittle, it will bend laterally to some extent without breaking, and it easily outperforms recent S30V in edge-holding: So for a 1940s factory, stainless can't be that hard to heat treat right...

Yes, Randall doesn't use stainless on blades bigger than 9" (probably because they worry a lot about reports of breakage, and their square cut stick tangs don't help), but they also say, contrary to what all their users can easily observe, that their 0-1 Carbon holds an edge longer than their 440B stainless...

The "Severe pitting" I described on my 5160 knife may have been an overstatement: I did say it went away with just sanding. To me, 1/8" orange spots all over is pretty bad... My 5160 was about like this knife below in less than two hours, although now that I think of it, the rust spots were kind of more "black" than really orange, for some reason:

It was surface rust basically.

Anyone who think 1800s frontiersmen would not have been all over stainless steel is just kidding themselves.

What Jay Fisher points out about the delusion that stainless is "weak" is that people say it won't bend as far as a carbon steel without breaking, therefore they conclude that it is brittle... What they fail to realize is that the effort required to get it to bend the same amount is far greater, which means it actually takes more force to break it... Stainless is in reality stronger than carbon steel in many cases, and can be optimized to be far stronger...

The only reason I like my 5160 knife is that it over twice as easy to sharpen in the field as stainless, but it is less than twice as fast to dull (if kept dry!): When you make a ratio of the sharpening effort vs edge endurance, it is worthwhile, but that is about it. If you don't expect to do full edge reprofiling in the field, by which I mean beyond the slight edge apex touch ups that stainless easily allows, but full fledged edge re-profiling from very heavy use, then there is no justification for carbon steel whatsoever.

Gaston

 

[KingMC]

Yes heat-treating stainless for 1800s one-man "Frontier" forges probably would have been a challenge...: But most large "quality" knives of the time were English-made in large factories. What probably would have happened is that the English factories would have gotten better and mastered stainless. So you would have local one-man forge production in carbon, and, increasingly as time went on, English imported production in stainless, with superior edge-holding... Given the ease of sharpening, I concede there would probably still be a lot of the cheaper carbon blades about, but they would be considered second rate, especially for quality weapons that sit a lot without being used.

Properly tempered stainless is not easy to break, and you can make swords out of it, just ask Jay Fisher. I have a cheap French Sabatier Jeune Boy Scout knife of the 1940s that is stainless (a fairly large 7" blade): It is not brittle, it will bend laterally to some extent without breaking, and it easily outperforms recent S30V in edge-holding: So for a 1940s factory, stainless can't be that hard to heat treat right...

Yes, Randall doesn't use stainless on blades bigger than 9" (probably because they worry a lot about reports of breakage, and their square cut stick tangs don't help), but they also say, contrary to what all their users can easily observe, that their 0-1 Carbon holds an edge longer than their 440B stainless...

The "Severe pitting" I described on my 5160 knife may have been an overstatement: I did say it went away with just sanding. To me, 1/8" orange spots all over is pretty bad... My 5160 was about like this knife below in less than two hours, although now that I think of it, the rust spots were kind of more "black" than really orange, for some reason:

It was surface rust basically.

Anyone who think 1800s frontiersmen would not have been all over stainless steel is just kidding themselves.

What Jay Fisher points out about the delusion that stainless is "weak" is that people say it won't bend as far as a carbon steel without breaking, therefore they conclude that it is brittle... What they fail to realize is that the effort required to get it to bend the same amount is far greater, which means it actually takes more force to break it... Stainless is in reality stronger than carbon steel in many cases, and can be optimized to be far stronger...

The only reason I like my 5160 knife is that it over twice as easy to sharpen in the field as stainless, but it is less than twice as fast to dull (if kept dry!): When you make a ratio of the sharpening effort vs edge endurance, it is worthwhile, but that is about it. If you don't expect to do full edge reprofiling in the field, by which I mean beyond the slight edge apex touch ups that stainless easily allows, but full fledged edge re-profiling from very heavy use, then there is no justification for carbon steel whatsoever.

Gaston

If they didn't even have knowledge of how to make stainless steels back in the 1800s what makes you think they'd not only have the capacity to produce knives in such steel but also the knowledge and skill to heat treat them to anywhere close to what the simple carbon steels were at back then.

You can apply to your argument your biases against carbon and PM steels all you want, that doesn't mean that what you say is anywhere remotely close to what the reality would be. The average stainless steel is more expensive to manufacture, more complicated to heat-treat, more brittle when heat-treated properly, and harder to sharpen when heat-treated properly, when compared to the average high-carbon steel. All these traits would make it much more expensive and give it so many downsides when being used by the 1800s-era outdoorsmen that they'd be much more likely to choose the simple and tough high-carbon steels.

 

[Yonose]

Yes heat-treating stainless for 1800s one-man "Frontier" forges probably would have been a challenge...: But most large "quality" knives of the time were English-made in large factories. What probably would have happened is that the English factories would have gotten better and mastered stainless. So you would have local one-man forge production in carbon, and, increasingly as time went on, English imported production in stainless, with superior edge-holding... Given the ease of sharpening, I concede there would probably still be a lot of the cheaper carbon blades about, but they would be considered second rate, especially for quality weapons that sit a lot without being used.

Properly tempered stainless is not easy to break, and you can make swords out of it, just ask Jay Fisher. I have a cheap French Sabatier Jeune Boy Scout knife of the 1940s that is stainless (a fairly large 7" blade): It is not brittle, it will bend laterally to some extent without breaking, and it easily outperforms recent S30V in edge-holding: So for a 1940s factory, stainless can't be that hard to heat treat right...

Yes, Randall doesn't use stainless on blades bigger than 9" (probably because they worry a lot about reports of breakage, and their square cut stick tangs don't help), but they also say, contrary to what all their users can easily observe, that their 0-1 Carbon holds an edge longer than their 440B stainless...

The "Severe pitting" I described on my 5160 knife may have been an overstatement: I did say it went away with just sanding. To me, 1/8" orange spots all over is pretty bad... My 5160 was about like this knife below in less than two hours, although now that I think of it, the rust spots were kind of more "black" than really orange, for some reason:

It was surface rust basically.

Anyone who think 1800s frontiersmen would not have been all over stainless steel is just kidding themselves.

What Jay Fisher points out about the delusion that stainless is "weak" is that people say it won't bend as far as a carbon steel without breaking, therefore they conclude that it is brittle... What they fail to realize is that the effort required to get it to bend the same amount is far greater, which means it actually takes more force to break it... Stainless is in reality stronger than carbon steel in many cases, and can be optimized to be far stronger...

The only reason I like my 5160 knife is that it over twice as easy to sharpen in the field as stainless, but it is less than twice as fast to dull (if kept dry!): When you make a ratio of the sharpening effort vs edge endurance, it is worthwhile, but that is about it. If you don't expect to do full edge reprofiling in the field, by which I mean beyond the slight edge apex touch ups that stainless easily allows, but full fledged edge re-profiling from very heavy use, then there is no justification for carbon steel whatsoever.

Gaston

The first sentence of the last paragraph still sums up why people still prefer these blades! If it's for hard use, and ends up hitting something it shouldn't and chips, twice as long to sharpen. Plus, i gave up trying to sharpen even the lowly d2 without a diafold; those might have been unavailable if not unaffordable back in the time of Daniel Boone. Forget about s110v. (Which I realize is not what you're referring to, since particle metallurgy wasn't even conceived by da Vinci)Chromium was only discovered by westerners only in the late 1700's, but ancient Chinese (3rd century BC) had figured out that a coating of chromium oxide would preserve iron weapons. Since it was initially used as a pigment, it was probably discovered by mistake. I don't know why more people don't seem to go nuts over ray ennis' 7" to 9" blades in 1/4" 440C, (which I wouldn't reprofile without a dmt diamond sharpener)or bowies made from 12c27(which definitely bends before breaking and easy to sharpen). Had chromium alloys been used back in those days trappers would have had one more point of contention amongst themselves especially after a few glasses of whiskey!

 

[Gaston444]

Actually stainless was discovered during or just before WWI, when they were testing different alloys to try to improve the endurance of artillery barrels. To distinguish the different barrels they used etched markings, and one day they made one barrel that would not take the etching... Interestingly enough, the researcher testing this immediately noted down something along those lines: "While this material is not suitable for artillery, its resistance to staining would be of excellent value for cutlery applications."

Gaston

 

[Yonose]

Actually stainless was discovered during or just before WWI, when they were testing different alloys to try to improve the endurance of artillery barrels. To distinguish the different barrels they used etched markings, and one day they made one barrel that would not take the etching... Interestingly enough, the researcher testing this immediately noted down something along those lines: "While this material is not suitable for artillery, its resistance to staining would be of excellent value for cutlery applications."

Gaston

Were these military researchers continental European, British, American or Asian? I can't find definitive answers anywhere.