Some newbie observations, and a question.

PetrifiedWood

Well-Known Member
Ok, I have made perhaps 20-30 knives so far. Not sure the exact number. I have been using O1 exclusively.

I've been quenching in mineral oil at about 130-140 degrees F. This gets the steel hard as verified by a set of hardness testing files. I also made a few "flint and steel" strikers out of O1, and as you may know, they will only throw sparks if they are sufficiently hard. Using the mineral oil quench, they did get hard, as verified by the files, and their ability to throw sparks when striking a sharp flint.

I subbed out some laser cutting and had a bunch of the strikers made, but they were made with 1095 instead of the O1 I'm used to. I ran the same temperature program in my kiln (Evenheat's website suggests the same for O1 and 1095). And, I quenched the 1095 in the same mineral oil. But, the strikers didn't spark! They also didn't harden according to the testing files.

So I tried a water quench and sure enough, the 1095 got nice and hard, and the strikers sparked just fine. I think I read elsewhere on this forum (perhaps even one of you guys pointed me in the right direction) that 1095 needs to quench to below 400 degrees F in about 4 seconds, while O1 is more forgiving with a 12 second time. My experience with the oil and water quenches would seem to support this.

Oddly enough, water quenching the strikers has caused some warping (not an issue given their intended use), but after making approximately 10-15 of the 1095 strikers and water quenching all of them, I've only ever heard the "tink" sound once that indicates a crack, though the striker did not come apart.

Still, I want to find a less violent quenchant that is easily sourced so I can start using steels that require faster quenches, but I don't want to have to special order purpose made quenching oils. A friend of mine who makes knives swears by regular old vegetable oil. It's certainly cheap and readily available, but the smell of rancid oil is nasty. His 1095 knives do get hard though and he has a guy that checks them with a real hardness testing machine.

And if I want to make springs from O1, what temperature do I need to temper them? And, how critical is it to get the blades into the tempering oven before they cool down to room temp?
 
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Kevin R. Cashen

Super Moderator
... that 1095 needs to quench to below 400 degrees F in about 4 seconds, while O1 is more forgiving with a 12 second time. ...

O-1 should give your around 8-10 seconds to get to 900F before you start losing significant hardness. 1095 is just a hair over .5 seconds, (that's right just a bit more than one half a second) aside from carbon content you couldn't have two more different steels.


but I don't want to have to special order purpose made quenching oils.

Out of curiosity, what is the reason behind the hesitation? The cost is the most common catching point, is that the case here, or is there another reason?
 

Doug Lester

Well-Known Member
As Kevin pointed out, the critical point that you need to beat on the IT diagram is not the Ms point, I assume that is what you are referring to with the 400° reference, but the nose of the cooling curve. If you don't beat the nose then the steel will start converting to pearlite and maybe upper bainite. That's usually in the 900-1000° F. range, depending on the alloy. Another thing to take into account, especially with 1095 is the manganese level. That is about the only thing in that alloy that regulates the depth of hardening and the distance to the right of the nose of the IT diagram; O1 has chromium and tungsten to help with the shift. The manganese levels in 1095 can vary considerably. A low level can be great for displaying a hamon/quench line but it can be difficult to get the steel to harden and any vegetable oil will be too slow to get it to harden properly. Also, a brine or water quench will accentuate anything that will cause irregularity in cooling so I would consider it normal to have more of a problem with warping as well as breaking.

Doug
 

LRB

Well-Known Member
Do yourself a favor and buy the proper oil for the 01. As far as the 1095 strikers, I don't know what temp Evenheat recommends, but 1475° is all that is needed for either of those steels. I make quite a few 1095 strikers and use a brine quench at about 100° to 110°. They don't crack and they don't break. So far. I was getting cracks on occasion when using water, but the brine and lowering the oven temp from 1500° to 1475° seems to have stopped mine from cracking.
 

Sunshadow

Member
Proper oil is an investment that seems steep until you amortize it over the lifetime of the oil by the number of blades you can use that oil for if you take care of the oil. I resisted spending that money for a long time, after all I was getting knives that held an edge well and didn't break, then I had an opportunity to get a bucket of Parks 50 when I had money in my pocket and got it, the first blades I quenched in it felt different on the sharpening stones and started popping hairs a whole grit level earlier without a noticeable loss in durability. O-1 is very forgiving of your oil choice as long as you nail your soak and austentizing process, 1095 not so much. If you are not going to get the proper oil and will not switch to a more forgiving steel, your only real option is brine. Brine raises your boiling point over that of water so it will absorb more energy before boiling which gives you a faster quench. As brine boils, salt precipitates out of solution providing nucleation sites for steam bubbles which helps control cavitation by replacing large steam bubbles which cause large areas of no cooling and subsequent warp/stress with much smaller more uniform bubbles. This speeds up the cooling but lowers the warping as the steel hardens (read more aggressive quench but lower probability of being visited by the "tink" fairy) if you have ever seen high speed video of a japanese blade being water quenched it writhes around like a wounded snake as thermal contraction hits followed by dimensional changes associated with phase transformation

-Page
 

Doug Lester

Well-Known Member
Page, I've seen a video of a Japanese swordsmith quenching a blade in a fish tank of water at normal speed and it was dramatic, it must have looked wild in slow motion. He considered the loss of 1 in 4 blades par for the course but looking the way that the blade first curved towards the edge and then reversed the curve to form the sori, it's amazing that any blade survives a water or brine quench. It would be interesting to see what happens with warm oil but the idea of filling up a fish tank, he looked like he was using a 100 gallon long tank, is a little daunting. Plus there would be the problem of wiping up 50-75 gallons of oil if for some reason the sides gave out.

Doug
 

LRB

Well-Known Member
I would never quench a 1095 blade in water or brine. Parks #50, first choice, or canola oil a second, but brine does great for me with strikers.
 

Doug Lester

Well-Known Member
The problem is that I have had 1095 that would not quench in vegetable oil. It may have quenched in Parks#50, but that was not something that I could invest in at the time. There may well be some 1095 out there that is so low in manganese that it will require something as aggressive as water or brine. Also, I'm at a bit of a loss to understand why you would quench 1095 strikers in brine but not a knife blade. If the canola oil or Parks #50 is not getting the steel as hard as you want it for the strikers wouldn't that indicate that you might be getting a slack quench with the canola or the Parks?

Doug
 

One

Banned
Strikers tend not to crack as much as knife blades with water or brine quenches, because of different geometry.

Keep in mind that geometry plays a major role, and that thinner sections and/or areas naturally cool faster. The wedge shape geometry of knife blades makes them somewhat more problematic.

With canola, you are probably best off keeping the maximum thickness 1/8 inch or under on 1095. However, I wouldn’t expect it to go over a Rockwell 65-66. It will work reasonably well on thicker 1095 blades from a practical standpoint, but you'll likely see a slight tapering off in hardness towards the spine.

Canola has the advantage of being one of the most stable vegetable oils, although there are some that are a bit faster. At any rate, the type of steel being quenched and the geometry also play a role.

As mentioned, using canola will only save money in the short run. Because of it’s relatively low stability compared to petroleum products, it has to be changed out more frequently which can add up. However, for low volume shops it may be the best alternative.

In an industrial context, price is not usually listed as a disadvantage of commercial quenching fluids. The list of disadvantages of the petroleum based engineered quenching fluids as compared to the vegetable oils usually goes more like this, while vegetable oils just have the issue of stability.:

#1. Poor availability for low volume shops.
#2. Poor biodegradability.
#3. Toxicity.
#4. Flammability.
 
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PetrifiedWood

Well-Known Member
Thanks for all the responses! I guess I will have to invest in some industrial quench oil then if I want to do anything in 1095.

To answer Kevin's question:

I think more than anything it's the hassle of obtaining and storing the industrial stuff. My wife and I are house hunting right now (need more room) and when we find the right place I will be able to use the garage as a shop. Right now I am using a 12X16 storage barn for a shop, and I have already run out of counter space so I get to kneel on the floor to use my blast cabinet, and I have my spindle sander set up on top of my table saw, etc. And I want to add some more tools like a milling machine and a bigger lathe eventually.
 

Kevin R. Cashen

Super Moderator
Thanks for all the responses! I guess I will have to invest in some industrial quench oil then if I want to do anything in 1095.

To answer Kevin's question:

I think more than anything it's the hassle of obtaining and storing the industrial stuff. My wife and I are house hunting right now (need more room) and when we find the right place I will be able to use the garage as a shop. Right now I am using a 12X16 storage barn for a shop, and I have already run out of counter space so I get to kneel on the floor to use my blast cabinet, and I have my spindle sander set up on top of my table saw, etc. And I want to add some more tools like a milling machine and a bigger lathe eventually.


Oh Boy! Don't even get me started on the shop space thing. I was bursting at the seams in my shop as it was before I moved in a U.S. Machine Tool mill last fall and began the tear down a restoration of the thing (it didn't really need it but I can't sleep at night until I do this with any equipment I get). To make it work I had to eliminate some of my old equipment and totally rearrange my shop. So now one can walk down carefully made paths in my shop but I still need to make room for huge surface grinder I plan on adding to the mess in the upcoming months; and then there is the 5 foot long surface plate I just managed to snatch up but need and make a stand for:rolleyes:.

I was just curious as to the main reasons many folks choose their quenchants, and equally as so when somebody says they want to avoid a particular kind of quenchant. If one can buy in quantity is is better for quality quenching oils and storage is a valid concern. I have a significant amount of space in a storage room devoted to oils, high and low temp salts and other drums, vats and cans of goodies.
 

PetrifiedWood

Well-Known Member
Yeah, the shop size thing requires a lot of creativity at times! You mention surface grinders. I hope to one day try this idea I have for making a "good enough" surface grinder using some drawer glides, magnets, a hinge and an aluminum block and just mounting it under the contact wheel of my grinder. I already have the ball bearing drawer glides but I guess that whole idea should be the topic of another thread.
 

LRB

Well-Known Member
Yes Doug, you always get a slack quench with any oil and 1095. Even Parks #50. The only quench that will max 1095 is brine, or water, but that includes the risk of cracking, especially with thin stock. Using a proper oil such as Parks is a compromise that usually gives a close enough hardness while lessening the risk of losing a blade. As ONE mentioned, with strikers there is more mass involved than in a blade. I got cracks in my strikers occassionally using water, but not with brine, which is the faster of the two, but gives a more even cooling effect.
 

Doug Lester

Well-Known Member
I guess we are seeing why there are those who will not use 1095 for knife making. You either have to choose incomplete hardening, aka slack quench, or risk cracking blades beating out the the nose of the IT curve. My personal choice would be to quench in brine and get complete conversion to martensite and temper back from there. Then there are those occasional makers who say that they water quench even steels like 5160 and 52100 and claim that they almost never have anything break.

Doug
 

Jericoh

Well-Known Member
I started off using warmed canola, but now use brine exclusively for 1095 in all thicknesses from 1/8" to 3/8". Only had one blade crack but that was my fault for grinding it to thin, and rarely have any warpage, again only when I grind them too thin.
 

Kevin R. Cashen

Super Moderator
...Then there are those occasional makers who say that they water quench even steels like 5160 and 52100 and claim that they almost never have anything break.

Almost all the claims of this that involved martensite that I have seen involved severely under-soaking to rob the process of the carbon necessary to promote cracking; once again we are back to not fully hardening just in a less obvious way such as a pearlitic spine. Instead of a macroscopic hardening line, you have massive amounts of undissolved microscopic carbide and anemic martensite. These steels were designed to fully harden with oil, how does one get around that without some sort of compromise?

Also, it is true in my experience as well that 10XX series steels will always have some level of fine pearlite, but the trick is minimizing it as much as possible. I have found that with the right fast quench oils and very tight temperature controls in the soak you can reduce the pearlite down to levels that are not even worth counting even in 1095. I have hardened 1095 blanks approaching 5/16" at the spine to where the only part that is not at least 65HRC is a zone in the center of the blade approximately 1/8" from the spine and about 2 mm across, consisting of very fine pearlite colonies dispersed among the martensite. I am convinced that the reason bladesmiths dislike 1095 is that it cannot be heat treated like 1084 and many feel that since it is a 10XX that it can. The result is nothing but troubles and disappointment in a very good steel that should meet or exceed expectations.
 

TDPurcell

KNIFE MAKER
if you have ever seen high speed video of a japanese blade being water quenched it writhes around like a wounded snake as thermal contraction hits followed by dimensional changes associated with phase transformation

Does anyone have a link to these videos? I've searched and cannot find them.
 
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