So what did we just learn aboout 1080

C Craft

Well-Known Member
Bare with me when you start to read this as it is really about knife making! I am not sure exactly how this fits into heat treating of 1080 but, it has got me thinking why this happened!

I was doing a repair on the frame for my bagger on on my riding lawnmower and needed a short piece of metal bar to use as a support.I dug into my scraps bucket and pulled out a short piece of 1080 flat bar left over. It would be perfect for what I needed. After welding the scrap to bar on the lawnmower I needed to drill a hole in it for the bolt that holds it in place. In a hurry and in an effort to get done I grabbed the water hose to cool the weld.

The scrap of 1080 was now so hard that I could not touch it with a bit too drill it! So I punched a hole through it with my welder. Once mounted on the lawnmower I realized that the angle was off on the support. Thinking, no problem I grabbed my homemade turner made from a large monkey wrench and I am going to bend it to where I needed it too be!

However when I put pressure on it it snapped at the weld, (not the weld itself) like glass. So before you tell me, I realize I cooled the weld too quickly. But I also found out some other realizations!

The 1080 got extremely hard when water quenched, and since it was not normalized and tempered it was also very brittle. So I guess what I am saying is I realized 1080 can be water quenched. I am not what the success rate would be using a water quench for blades but it definitely needs to be normalized and tempered afterwards to make a knife blade that is not brittle as glass.

This was a chance discovery for myself as I have always used Parks to to quench my 1080! Does anyone have experience using 1080 with a water quench? What kind of results did you get?
 
the first 1084 blades I made I quenched in hot(120F) brine. one was ok, one had small crack, and one warped. when moving the warped one to a vise, i dropped it and broke into 3 pieces. will try again someday with plain, room temp water.
scott
 
Brine is less violent to the steel, and you will notice the difference immediately when the blade goes into the water. Plain water does not cool as evenly as brine, and therefore just adds more risk to cracking your blade.
 
Yes, I am thinking it could be done with 1080, ( a water quench) but don't think the success rate would be high! This was really a chance discovery and just got me too thinking. Was anyone making blades from 1080 and quenching in water! So I guess this was more of a "what if" type question brought on by a chance realization!

I think you would be living in fear of the dreaded "tink" using this process!
 
Yes that is what I normally use Wick is Parks 50 but I just had to ask if anyone was using water after my accidental discovery of how hard that piece of 1080 got once I welded on it and then cooled with the water hose

Based on the fact that I haven't got any replies I am going to guess no one does it! I know it also made the steel very brittle. So if you got away with a water quench it would need to be normalized and tempered rather quickly.
 
Much of the hardness from welding it is probably, or possibly, because welding causes the same condition as work hardening, and needs to cool slowly, or be normalized. This was discussed recently on MLF. I don't weld, so I really can't say for sure.
 
Just as a picky point, normalizing and tempering without hardening in between wont help much. Welds and the associated heat affected zone around them could well cool fast enough to harden without water.
 
I think that it is a bit of a misconception that, certain quenching mediums are always right or wrong based solely on the steel type. There are other factors and influences to consider, especially geometry/dimensions or part design and their inherent thermal gradients or lack of. Steel quality, forming method (cast, machined or forged) etc., can also play a role. Probably the most important thing is the intended “end use” of the part or tool, which dictates the heat treatment etc.

When choosing a quenching medium, speed is not the only factor.

In a comparison between Parks #50 and canola (since they’ve been mentioned) the cooling rate is comparable (fast) through the initial part of the quench where speed is necessary to achieve desired microstructures and properties. However, there are differences in cooling mechanisms, viscosity etc., that can be important to understand. The petroleum based fluids exhibit 3 mechanisms or stages in order, vapor phase (slow), boiling phase (fast) and convection. However, vegetable oils including canola, cool the steel with one mechanism, convection, and there is virtually no vapor or boiling phases. What this means is that the canola will cool the steel more evenly with less stress. If we look at the typical wedge or triangular cross section, the thinner edge section naturally cools faster than the thicker spine, because of the inherent thermal gradient. So with the petroleum based medium there are different cooling mechanisms at play on different sections of the blade during the quench, that exhibit different cooling rates at the same time. What this does is increases the stresses of the inherent thermal gradients and can lead to cracking, excessive micro fracturing and distortion. During the low temperature phase of the quench, where transformational stresses are a concern, both the vegetable oils and the petroleum based oils exhibit the same mechanism. The speed of this part of the quench is regulated by the viscosity of the quenching medium. The slower the quench in this phase the less stress to the steel. The higher the viscosity the slower it is, and the lower the viscosity the faster it is. The Parks has a very low viscosity, lower than the vegetable oil.

Water also cools by the same 3 mechanisms as the petroleum based mediums, but has a much lower viscosity than either of the other two. This makes warping, cracking etc., a major problem with water, and brine quenching, during the transformational part of the quench and it‘s inherent stresses.

Though the overall fastest quenches (water/brine), may squeeze and extra point or two of hardness out of the steel, the disadvantages and risks make them impractical, especially on high carbon, long and thin, problematic thermal gradients,… crack and distortion prone parts such as knife blades.
 
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Brine is less violent to the steel, and you will notice the difference immediately when the blade goes into the water. Plain water does not cool as evenly as brine, and therefore just adds more risk to cracking your blade.

will try 10% brine again when i do my next batch of heat treating. I think part of my problem was size and shape of quench container and that the blades may have moved side to side instead of up and down. a 6" piece of 1084 won't break the bank.
scott
 
Thanks for the info on this one guys as I was really serious about the tittle. What did I just learn? I think from my point of view I learned that with 1080 quenched water will make it hard but brittle. I am not sure if normalization and tempering would have helped the 1080 at all because it may have already had fracturing due the water quench and also I don't really know what part the welding had to do with all this. Meaning the temp that the metal was subjected too by welding. So in short there are a couple of factors here that I really don't know for sure what part they played in this little accidental experiment!

I guess I was just surprised how hard the 1080 had gotten. I could not drill it. So I tried to spot anneal and once red hot I hit again with speed and pressure on the drill press and literally burnt the bit up. The bit caught on fire and the tip melted off of 5/16" bit. So I concluded it had gotten extremely hard but once I bolted it up and the fit was off, with the pressure I applied to readjust the fit, I snapped the metal in a line parallel to the weld. So I concluded it must have also made the metal brittle.

I am not sure at all that this has anything to do with knife making but it did put my mind to thinking that if you could get past the dreaded "tink" in water 1080 might get very hard and with normalization and tempering you might have a decent blade. In a way this thread was intended to open a discussion and in a way I was questioning what I had just experienced, not exactly sure what to make of it!

However knowing what I have done in the past with 1080 steel, using Parks50 as a quench, and proper normalization and tempering heats, I think I will stick with that for a quench when it comes too making knives from 1080! A water quench sounds like a crap shoot at best and the problems seem to out weigh any possible great benefits!
 
I have only done this once and per the instructions of you tube (this was before i discovered knife dogs) I used motor oil after allowing the blade to cool a few times at room temp. I had to pound it hard with a ball peen to get a large crack out of one side where it looked like it had been folded. It was pretty crappy stuff to begin with, but its what I had laying around. My first batch of 1084 should be arriving soon, so can't wait to get started on my first real project. Any suggestions to avoid that "dreaded tink" which I can only assume is the blade cracking?
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I would recommend canola oil if you have no Parks #50. Motor oil sucks as a quench oil. Warm the canola to around 125°, quench, and temper ASAP.
 
Canola is closer to something like AAA, than to #50. #50 is closer to water, but not quite as severe.
 
Getting blades to harden isn't as much of a problem as warping, excessive micro fracturing and cracking. This is because of the long, thin, wedge shaped cross section and profile of blades in general,... something to consider when choosing a quenching medium.

Geometry or specific part/blade design and the intended end use of the tool, play much more of a role in heat treating than the speed of the quenching medium alone.

Again,... it’s a misconception that any particular liquid quenching medium is always appropriate, better or best, based solely on the steel type or specific alloy.
 
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