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Discussion in 'General Knife Discussion' started by Dr Rez, May 5, 2017.
All things being equal which of these steels has a higher degree of toughness?
Probably A2 -- check out Knife Steel FAQ (http://www.zknives.com/knives/articles/knifesteelfaq.shtml) -- but a lot depends on heat treat, blade geometry, etc. My Bark River Woodland took a marvelous edge but was tougher to sharpen than 1095. Here are some notes from a review I did on that knife about 10 years ago. A-2 includes carbon (1%), chromium (5%), silicon (.4%), manganese (.6%), molybdenum (1%) and vanadium (.25%). The legendary Bob Egnath called A-2 “…an exceptional steel, with fine wear-resisting qualities plus excellent resistance to annealing and warping. Grinding is noticeably harder than 0-1 but not extremely difficult. Sawing is tougher and relates to the five percent of chrome in this steel’s chemical makeup. Really nice to finish with the grinder and very little grain appearing in the buffing. Excellent flexibility. Phil Hartsfield gets incredible cutting ability out of this steel.” Joe Talmadge’s take on A-2: “An excellent air-hardening tool steel, it is known for its great toughness and good edge holding. As an air-hardening steel, so don’t expect it to be differentially tempered. Its outstanding toughness makes it a frequent choice for combat knives. Chris Reeve and Phil Hartsfield both use A-2, and Blackjack made a few models from A-2.” The Bark River website notes that it treats its A-2 “… to achieve maximum grain size.” I was a bit confused about this, having the impression that small grain size is preferable, so I asked Mike Stewart in the Bark River forum on KF to explain. He promptly answered, “All of our blades are double quenched to maximize any growth or refinement in the blank. We then refine the grain structure with alternating draw and cryo processing. A-2 has a very fine grain structure. Our complicated process makes the best use of all ferric, chromium, molybdenum and vanadium carbides in the steel. I have had others ask the same question and if my answer is a little non-specific, it is due to the fact that I am reluctant to give out details that I consider a trade secret. Please do not think that I am one of the individuals that think I am some master of steel. I have been making knives for over 20 years and have found methods that really make steel perform to a much higher degree than most others. I was the first semi-production or production maker that used 52-100 on a regular basis. My choice of A-2 for the Bark River line was because it is a real performer if treated and ground properly. Most collectors and users don’t know that when purchased in large batches, 52-100 actually costs one fourth the price of A-2. Trust me, if I thought that steel like 52-100 were better I would use it. In short, maximum grain growth is an oversimplification of terms but the process the way we do it does eliminate any molecular voids and gives a stronger and more uniform blade.”
In most of the "hard use" applications where these two steels are chosen for production knives,"all things" are not equal. Some of the 1095 "tough" knives are left as soft as 55Rc, whereas A2 tend to be in the "58-60" range with 60Rc generally considered to be the "sweet spot" for knife use. Mike Stewart of Bark River pointed out that for his company, A2 costs 4 times as much as 1095, so that is a factor in the choice of 1095 for some manufacturers. I don't use 1095 because I have a lot ofW2 and 1084.I harden both to at least 60Rc.
As for 52100, folks have discovered in recent years that it is a fairly different steel when heat treated for toughness using the lower austenizing temperature. In the past, people used the 1550F or so temp and got a steel with lot of abrasion resistant chromium carbides suitable for bearings. With the low temp, you get a steel with small carbides and small aus grain that is quite tough.
A2 is tougher
I'd put A2, 1095 and O1 at about the same toughness, given similar hardness. A2 will hold an edge a bit better than 1095 and O1 and be a little more corrosion resistant.
All things being equal, A2 blows away 1095. Take a look at this chart by relentless knives. https://www.google.com/search?q=ste...i=DNoMWbCnJMrTjwSv9ICADA#imgrc=45pY8nQBidZHvM:
and here is an A2 spec sheet by Crucible. http://www.crucibleservice.com/eselector/prodbyapp/tooldie/airkoolt.html
It shows Charpy C-notch value of 41 ft-lbs at 60 Rc (500 F). That's pretty extreme toughness. It's tougher than O-1, everything else being equal. Only 5160, L6, the S series, and the powdered steels are tougher. I don't have the 1095 Charpy value, but it won't get to half of that, I'm sure. (If anyone has the 1095 Charpy value, please post the link here. Thanks.)
Some years back Aaron Gough ran a series of blind tests over in the knife makers section here on BF. If someone has better search fu than I, they might find it and link it here. Certainly would pertain to this discussion. Little A2 edc on my belt right now.
There are so many comparison charts on the web, many with contradictory claims, that it's difficult to get a straight answer, especially when so many of the characteristics of steel are in the heat treat.
But Crucible shows that O1 -- which is very close to 1095 on the toughness scale -- is equal to A2 for toughness. A2 will give you a bit more wear resistance.
Check out Crucible's comparison chart at the bottom of this link (Resistance to chipping is the toughness bar):
My own sense is that you don't get much difference in toughness -- resistance to chipping and breaking -- with 1095 and A2. Both are tough steels. You could drop the carbon down from 1095 a bit and soften the heat treat to get an even tougher steel. Or, if you could stand a little better wear resistance, you could go with a better steel, such as 3v or Vanadis 4 Extra.
But for just the two steels that the OP is asking about, they are so close that he should mostly pay attention to the large effects of heat treat, rather than the small differences between A2 and 1095.
You can achieve a finer grain and still get full hardness, that's the benefit of adding the alloying elements it improves the hardenabililty by taking up space in the grain boundaries where softer structures try to form upon quenching.
That means that if both blades were they same and both had the best heat treatment for the given task you could push the performance of A2 further since you could achieve a finer grain plus the additional harder chromium carbides for more wear resistance.
I don't think I've ever had my socks blown off but with the production knives I've used the A2 held a longer edge in use over the 1095 and 1095 crovan stuff.
You're in good company, Dead. Mike Stewart likes A2 much better than 1095. Chris Reeve chose A2, not 1095.
But there are so many variables that's not easy to say one steel is better than the other. Tops and ESEE went with 1095, not A2. Randall chose O1, which is much like 1095. Some knife makers don't like A2 because it has too much alloyed components.
Busse eschewed both and went with Infi.
L6 would be tougher than either. So would 3V or Vanadis 4E.
1095 has more carbon than it needs for toughness, and it loses toughness with the added carbon. But it also gains the ability to achieve higher hardness and improved wear resistance and greater strength. If you want more toughness, go with 1075.
Here's a knife maker who tested A2 for his machete and found it severely lacking:
But to my mind, it mostly comes down to the heat treat, and we hardly ever know anything about the heat treat. I had a custom knife made in 1095 that broke in half fairly easily, leaving the blade dangling by a thin flap of steel that remained. Another failed, too. I was so unhappy that I decided to test my other knives in abusive ways. Several failed. My Larry Withrow 1095 (San Mai) stood up to every thing I threw at it. So there is nothing wrong with 1095 or A2, per se.
But personally, I'm a big believer in the high-alloy steels, especially the super steels. If I want toughness, I'm not going to choose either 1095 or A2.
which is tougher depends on hardness. at lower Rc the choice would be 1095, at higher Rc A2.
here is a thread on the subject with some interesting comments by Roman Landes. http://www.hypefreeblades.com/forum/viewtopic.php?f=3&t=653&hilit=a2&start=20
"If you need more toughness there are also better alloys out there just to name few L6, S- series and those have the same advantages with less effort in HT, always assuming the HT is done right.
Futhermore if you go forging, the low alloy high carbon stuff can be adjusted in its micro structur faily easily compared to A2. While you prone to the factory outlet you bought the A2 because of its high alloy content.
So finally you have to tackle with all the same efforts you put into a stainless but not getting a stainless blade. You getting corrosion resistance close to carbon steel and hardness, edgestability and toughness can be get easier with simple steels and more simple HTs at a higher level.
In the case HT can be done right and you got all the stuff like cryo available A2 makes a good multi purpose steel.
But be aware the more multi, the less purpose you get."
In an industrial environment, A2 has about the same corrosion resistance as H13 and A36(plain jane cold-rolled). On top of that, A2 can cost 50% than O1.
part of the popularity of A2 is air cooled. no massive tanks of heated oil to quench blades. wrap in foil, put in furnace, when the timer dings, set on counter. wait 10 minutes. put in tempering oven and you are done. High alloy steels make great drill bits, taps, broaches, end mills, jet engine bearings, poop grinding blades..... For a fine edge, high performance knife, give me O7/1.2519 or Aogami Super.
With my ht - up until last week, A2 was tougher than 1095 at high hrc. Here is my latest 1095 hard chop tests (7 minutes video). Yep, 1095 can be quite good
But most companies out there do not use your heat treatment. The late Bill Moran said that in his experience, W2 was almost a tough as 5160, but took and held a much better edge. The reason that he stopped using W2 was that they stopped making it. My experience with W2 at hardnesses quite a bit higher than what many manufacturers use for 1095 is that it makes for a pretty tough chopper without restoring to edge quenching, etc.
Well heat treated 1095 its a hell of a steel! Seems that when tempering this steel to achieve the 55-57hrc mark you are hitting a peak of toughness and the edge will only have plastic deformation (not chipping) even when hitting granite stone! Another peak toughness for this steel is when you temper to achieve 65-66hrc. This informations are not my observations, are from reading what my steel gurus write and listening them! According to them, 1095 has a tempering embrittlement zone around 400F, the tempering temperature that gives the magic number 60hrc. That's why we see some 1095 knives failing in the field! So in my opinion well heat treated 1095 is much tougher than well heat treated A2. Wanna go even tougher? Go ModA8 steel! Wanna spend big money? Go Cpm3v or Vanadis 4 extra, but keep in mind this steels need a careful heat treatment, not for the average person to heat treat! When I want really tough stuff I go s series steels or k600.
Mike Stewart's answer is basically gibberish. It's not a good idea to hold all steels to the same hardness when comparing them, as different steels have different optimum ranges. Manipulation of the grain size in steels like A2 is more difficult than in lower alloy steels like 1095. Their grain sizes are both in the same range, say 8 to 10 on the fracture grain size, with 10 being the smallest on that scale.
Alloy steels are generally considered tougher than plain carbon steels, though there are half a dozen competing factors, or more. Higher temperatures during hardening result in fewer and smaller carbides for the same steel.
A2 ---- HRC-61 31 ft-lbs
A2 ---- HRC-60 41 ft-lbs
A2 ---- HRC-59 37 ft-lbs
A2 ---- HRC-58 29-33 ft-lbs
A2 ---- HRC-57 41 ft-lbs
1095 -- HRC-62 28 ft-lbs
1095 -- HRC-60 30 ft-lbs
1095 -- HRC-58 30-32 ft-lbs
1095 -- HRC-57 32-35 ft-lbs
* compiled from various sources
Seems I'm wrong. But charpy tests doesn't tell the hole storie, they can be used for guidance only.
Comparisons of toughness from different sources is tricky. Charpy testing has a lot of scatter and many charts don't specify the sample configuration.
That said, there's not much variation among sources (mostly steel manufactures). Also, when looking at steel composition (1095 vs A2), I'd have very hard time believing 1095 is tougher, at least in HRC ranges (57-62) which are quite common for knives.
Wouldn't surprise me. Again, alloy steels are generally tougher. However, it's not a hard rule.