Ready to do my first heat treatment!

U

Uhurungus

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Jan 8, 2015
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i made a small 3 brick firebrick forge and have a bernzomatic i'm using to heat it up. i have a blade ready to heat treat.
it's Aldo's 1084. am i ready to just heat it up to non magnetic and quench or do i need to normalize first? just when i thought i was ready to do this i'm now thinking that i have no idea what i'm doing.

lol i'm sorry guys, i know this is probably super annoying and something you've answered 100 times before. just that everything i read and watch on youtube is slightly different. not that the responses i get here in this thread will be anything different though...

here's my plan, heat up canola with a scrap piece of steel, heat the blade up to a dull cherry red color, check against a magnet until non magnetic, then quench. sound good?
 
Uhurungus said:
i made a small 3 brick firebrick forge and have a bernzomatic i'm using to heat it up. i have a blade ready to heat treat.
it's Aldo's 1084. am i ready to just heat it up to non magnetic and quench or do i need to normalize first? just when i thought i was ready to do this i'm now thinking that i have no idea what i'm doing.

lol i'm sorry guys, i know this is probably super annoying and something you've answered 100 times before. just that everything i read and watch on youtube is slightly different. not that the responses i get here in this thread will be anything different though...

here's my plan, heat up canola with a scrap piece of steel, heat the blade up to a dull cherry red color, check against a magnet until non magnetic, then quench. sound good?
Click to expand...

Not just to non magnetic, you have to go hotter


1414 f curie point non magnetic

1475 quench point,


something like that, do some research and verify the numbers
 
You could still heat it up to non-magnetic then stick it back in the forge for about 5 minutes to heat beyond initial magnetic test. By doing it that way you should reach critical HT. This is all kind of guess work you realize since you do not have a thermometer, but 1084 is pretty forgiving, that's why it is used by the beginner so much. Give that a try and you should be golden!
 
Cactus Kid said:
You could still heat it up to non-magnetic then stick it back in the forge for about 5 minutes to heat beyond initial magnetic test. By doing it that way you should reach critical HT. This is all kind of guess work you realize since you do not have a thermometer, but 1084 is pretty forgiving, that's why it is used by the beginner so much. Give that a try and you should be golden!
Click to expand...

5 minutes seems like a rather long time to get the last bit of heat in. Wouldn't be a big a deal in a 1500 degree forge/oven, but without a pyrometer/thermocouple to check temps I think you'd be way overshooting and getting some unwanted grain growth and decarb. I'd think 30 seconds to a minute longer would get you in the ballpark.
 
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please don't mistake this for me being argumentative, it's only an example of multiple answers for the same question.

QUOTE: 1084 is ready to quench as soon as you get it evenly to the popular non-magnetic standard.

this is taken from the second paragraph of post #7 in the stickied "counts thread" made by stacy apelt, posted by kevin cashen. from what i gather, these 3 are goto people when asking questions about knifemaking.

http://www.bladeforums.com/forums/showthread.php/673173-Working-the-three-steel-types.



most of the research i've done and answers i've received is that i probably DONT want to heat for another 5 minutes after non magnetic, as i'm just looking for +/- 50 more degrees. so depending on the forge, only a minute or so more.

question: are there any visual cues that i've done it or i'm doing it right or wrong?

ok i'm off to costco to buy 5 gallons of canola oil :thumbup: not to figure out how i am going to convince the wife this was a good purchase... it's bad enough when i come home with 3 lbs. of mayo
 
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I think what Kevin means by "non magnetic standard" is that the "standard" is to use the magnet to gauge where 1414 is and go past that one shade or two. The "standard" isn't AT non magnetic. The "standard" is just "past" non magnetic.

Non magnetic as stated by the Count is at 1414F. The magnet will START to stop sticking at 1350F and will totally NOT stick at 1414F. But you need to be AT 1475-1500 for 1084. So you need to be hotter than non magnetic. 80 degrees hotter there about. What we normally say when using the Mark I eyeball is "a shade or two past non magnetic".

If you quench AT non magnetic it will not reach max hardness.* You must go past non magnetic.

5 minutes in a 3 brick forge is WAAAAAY too long past non magnetic. If you wait 5 minutes more you will overheat and blow the grain. It may be about a minute more, maybe a minute and a half. But not 5.

*disclaimer....you CAN reach max hardness with this temp but there are secrets to doing it. Some hoodoo voodoo I think.
 
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The post doesn't say to quench at 1414 f. The comment is more to prove a point that 1084 is simpler to heat treat than 1095 as it doesn't need to soak at temperature. Also, the steel is still non magnetic at 1475 so the statement is still correct.
 
ahh ok, for a complete noobie it's all a little less than clear. you have to pick up little bits and pieces of info here and there and put it all together while you wonder if you missed anything or read something wrong or what have you. then you actually do it and there it is, i did it, but did i do it right? how do i know? should i have? maybe i didn't...

this whole journey has been nothing but complete fun and wonder and mystery since i started. can't wait to keep going.

thanks for the clarifications.

now i fired up my TS8000 bernzomatic and having problems getting a good flame. it wants to change constantly. the bottle would freeze my tongue if i touched it. there is frost around the air inlet holes. it's not quite like i picutred it and how the videos make it look. i have propane and maps gas. wondering if propane will even work... to be cntinued
 
The statement in the post is indeed misleading to someone learning how to heat treat.

"1084 is ready to quench as soon as you get it evenly to the popular non-magnetic standard" Actually, that is exactly how it sounds to me. 1084 is ready to quench once it is evenly non magnetic. That is how it sounds.

And I am wondering if this sentence is not the source of this phenomenon. Seems like most all new comers to heat treating are under the assumption that 1414F is the target temperature for 1084. I don't know how many times I have had to say, "No it needs to be hotter".

Also, propane is not the best for your set up. Get the yellow bottles. MAP/PRO I think it's called. That's what I used in my first heat treat forge. Worked great.
 
Uhurungus said:
please don't mistake this for me being argumentative, it's only an example of multiple answers for the same question.

QUOTE: 1084 is ready to quench as soon as you get it evenly to the popular non-magnetic standard.

this is taken from the second paragraph of post #7 in the stickied "counts thread" made by stacy apelt, posted by kevin cashen. from what i gather, these 3 are goto people when asking questions about knifemaking.

http://www.bladeforums.com/forums/showthread.php/673173-Working-the-three-steel-types.



most of the research i've done and answers i've received is that i probably DONT want to heat for another 5 minutes after non magnetic, as i'm just looking for +/- 50 more degrees. so depending on the forge, only a minute or so more.

question: are there any visual cues that i've done it or i'm doing it right or wrong?

ok i'm off to costco to buy 5 gallons of canola oil :thumbup: not to figure out how i am going to convince the wife this was a good purchase... it's bad enough when i come home with 3 lbs. of mayo
Click to expand...


REad Kevin's response in post 4 again

" the popular non-magnetic standard."
was used as a bit of a shorthand


http://www.bladeforums.com/forums/s...g-the-three-steel-types?p=7223147#post7223147

As for desired temp above Ac1, well when you consider the previous paragraphs and how much stability in grain size you really can have, then you can see why a eutectoid steel is the most heat treat friendly of them all.

If all you have is a magnet and a forge, a bit above 1414F (Ac2 or the "Currie point") will still work fine for you, if you have the ability to hold at 1500F even better, and you can assure total solution without any of the headaches that can arise with the hypereutectoid steel. Simply put all that carbon into solution and quench away!:thumbsup:

Now is a great time for another plug for Aldo and his 1084
Click to expand...
 
yep count, after clarification from this thread and some more digging i now know 1414 is without a doubt NOT the target temp for HT of 1084. thanks for the help.

as a noobie what i look for is complete start to finish info on certain processes. but that's hard to come by. that's why i appreciate nick wheeler's vids so much. it's ALL there. aaron gough has been super helpful as well as ed caffery. i listen to everything on these boards but certain people command more attention.

again, this resource is amazing and it's very appreciated that all you take you time to help out others and not just here to toot your own horns. it's daunting to post questions like these to you people. but i'm not gonna learn anything without risking looking like the fool.
 
ok so i did it.

actually them. plural as in 5 blades. i finished with the first one and couldn't think of a good reason not to do the others i had ready. all together took about 15-30 minutes total.

took 1 quart of canola oil in a clean paint can and heated up a piece of scrap metal to warm up the oil. i had 2 thermometers in there but didn't do a good enough job of figuring out the quench temps what with swirling currents in there. i got all knife blades to a color somewhere between orange and red, checked for magnetism, let it sit in the forge a bit longer, then quenched them. by the 4th knife i started to wonder what my oil temp was. turns out it was pretty warm. as in if i would have stuck my finger in there it would have cooked it. so i poured another quart into a different container and did the last 2 without an oil preheat. all kinds of things wrong with how it went down but i was alone, doing this for the first time, was a little jumpy and very ignorant and it unfolded exactly how it was supposed to i guess. learned a lot of stuff.

i have some questions now.

1. can i put the used quenchant back in the jug and reuse it? if so, can i keep reusing it? how long?

2. hardness testing: so i know about scating a file looking for grab. again i'm completely new and don't really know what to look for past book definitions that don't entirely make sense to me. one thing i can say is that the blade edge is definitely harder than the tang butt end. whether or not i did it adequate, i have no idea. not looked for anyone in town with a rockwell tester. i'm thinking maybe at this point that's a bit overkill. are there any other ways to test hardness on the cheap? hopefully i can go to a local forge (Oaktown or Bridgetown) and show them and see what they say. Polish Avenger has been kind enough to be my guardian knife making angel and we'll soon see each other too.

3. tempering: i did 2 tempers for 1 hour @400. does it matter if i do the file scate check before or after tempering? what about scale removal? is the vinegar soak before or after tempering? not sure i'm even going to do that, just wondering.

my plan is to take one of the 5 and finish it. just one. by the time it's done enough time will have passed that i'll be able to get better answers hopefully.

so it was not at all what i was expecting. my wife thinks i'm insane. the excitement level was off the charts and i had a huge smile on my face all afternoon. if this whole journey stops tomorrow it will have all been worth it. something about it is just simply magical.

i found a neighbor that has a bunch of dried laburnum wood that is very beautiful as well as some apple burl that he gave me. i should have a finished product soon.

thanks again for all your input and encouragement.

if anyone reading this is local to portland and wouldn't mind a visit from a noobie, please drop me an email. i'd love to pick your brain and see your shop.

tom@floathq.com
 
Yeah, the quenching is the most fun part isn't it?

Uhurungus said:
1. can i put the used quenchant back in the jug and reuse it? if so, can i keep reusing it? how long?
Click to expand...

I think until it goes rancid. I haven't noticed any change in my canola

Uhurungus said:
2. hardness testing: so i know about scating a file looking for grab.
Click to expand...

I've had mixed success with the file test. The scale will file off and look like scratches. The surface also can lose carbon I think and not be very hard. As long as you're confident about your hardening temperature I wouldn't worry about it. It will be hard enough. You can always do a piece of scrap and sharpen it. You can get a feel for the hardness by sharpening things.

Uhurungus said:
3. tempering: i did 2 tempers for 1 hour @400. does it matter if i do the file scate check before or after tempering? what about scale removal? is the vinegar soak before or after tempering? not sure i'm even going to do that, just wondering.
Click to expand...

Post-tempering the steel will be softer than a file, so the file test won't work.

I grind the scale off after tempering. It's generally warned that you should temper ASAP because of stresses in the steel that need to be relieved and could lead to cracking.

I haven't yet used a vinegar soak to remove scale. My last HT batch I used a clay and boric acid anti-scale mixture that seemed to prevent 90% of the scale. I think I will do that but with a slightly thicker coat -- some spots the carbon bubbled up thru. It was easy and seemed worth the time to apply it. Stacy is always talking about satanite for this but I haven't a clue where to source it and besides I'm a Christian :).
 
Good point on Kevin's comment. It is indeed a bit confusing to a non-metallurgist.



I will try and elaborate. Some numbers are slightly simplified. The point being made should be clear:

Steel is a mixture of carbon and iron. It takes right at .80% carbon and 99.20% iron to make steel with no leftover atoms. Lo and behold, 1084 has .84% carbon ( and very little else)....just enough with a very tiny tad extra for loss and such. It makes plain old steel with no carbides or extra alloy stuff to deal with. The small amount of manganese and occasionally a tad of vanadium added to 1084 make it quench easier and have a fine grain.

Martensite is made from austenite. Austenite is made by heating steel above the austenitic point, which varies depending on the carbon content ( and alloys)....somewhere in the 1420F-1500F range.

In the charts concerning how steel converts to austenite during heating, there is a low spot where three lines meet. It varies depending on what metal/alloy is being graphed, but for most simple carbon blade steels....somewhere around 1400°F. This is the eutectic point. Call it the perfect storm of iron and carbon coming together. This is right about .83% carbon. Wait, wasn't 1084 right at that carbon percentage,...... why, yes it was. Thus, 1084 steel is called "the eutectoid", meaning it has just the right amount of carbon, and will have the lowest temperature to allow all the carbon to join with all the iron. Since 1084 has no extra alloying to make carbides or other things, it doesn't need any time for these to dissolve. Since there is nothing in the way of the iron and carbon getting connected, the combination is nearly instant, and does not require extra time or temperature. That is why 1084 is the simplest steel to HT.

Now, few have forges capable of accurately telling when that magic number has been reached, and the actual temperature may vary a little depending on the makeup of the steel. So we need a fool proof method for newer ( and many older) smiths to know when the steel switches to austenite while being heated up. Along to our aid comes a neat thing from physics that says when the body-centered cubic structure of the cold steel (normally martensite and/or pearlite) suddenly changes to face-centered cubic ( austenite) as it reaches this magic point, it changes its ferro-magnetic properties - the steel stops being magnetic. This basically means that as the atoms switch how they hook up, the iron/steel stops becoming magnetic almost immediately. This all happens at ( or close to) 1414°F.

Taking all that info lets up know that 1084 needs to be just above the eutectic point, and that a magnet will stop sticking right about the eutectic point....thus, a very good indicator of the point ( or near it) when the steel is ready to quench.

So in practicality, once 1084 is heated "fully and completely" above the non-magnetic point, it is ready to quench.

What is done by nearly all smiths using the magnet to detect the Curie point is use their eye to "guestimate" small increments of temperature above that point. One shade of red brighter is about 40-50°F hotter. Two shades is 80-100°F hotter. Thus, you heat the steel a little more until you see the red color of non-magnetic brighten a noticeable shade or two.

Since the steel will start losing heat and begin cooling as soon as it is out of the flames of the forge, you need a little cushion above that magic point to assure all is austenite when you quench. For 1084, it does not need much, so heating to 1450F will be plenty...or about one shade redder than non-magnetic.

Now, for cooling, 1084 is pretty simple, too. It needs to cool fairly fast from above the eutectic point to below 1000F in a very short time. Fast oil does this just fine. Parks #50 at 80F is the perfect quenchant for 1084 and most steels with higher carbon content. Plain old canola oil warmed to about 120F will also do the job for 1084.

If it cools too slow and does not pass that range in time, the austenite becomes pearlite. This is not what we want at all..... we want martensite.

Once below that " pearlite nose" ( below 900F) things can and should calm down, and cooling become more even and leisurely. At this point, if the quench went well, the steel is super-cooled austenite. Once the steel reaches about 400F, a change happens where the ( still austenite) face-centered structure converts to body-centered martensite. This is the martensitic start point, or Ms. Once cooled below 200F, the martensite is fully converted....but very brittle. Tempering twice at 400F will cure that.

I hope this helps explain Kevin's theoretical talk in some practical terms.
 
Using one quart of oil at a time is too little, and as you see it becomes hot in a hurry



I'd start with a minimum of a gallon or two.


Yes you can reuse it.
 
thanks for the replies.

stacy - it pretty much made sense as it was written but for that one line. thanks for the clarification. now i'm off to try to find out if pearlite formation is something one can recognize visually. theoretically it all makes as much sense to me as i think possible at this point, but in practice i'm just looking for something that tells me i did it right. i'm starting to think that isn't going to be answered without experience. one person told me, "get in there and put an edge on one of them and start using it". if i'm good with the results then no harm.

count - absolutely, from now on a gallon at a time. if i'm quenching with a gallon, how many 8" blades do you think i can expect to get through before it's too hot? also, how much is too hot? i've not yet looked but off the top of my head i do remember a lot of info about what the starting quench temp should be, but not so much about how hot is too hot.
 
No need to overthink this .... with 1084 - If you got it hot enough, and cooled it quick enough ( in enough oil) - it is almost surely martensitic and hard.


You can't tell pearlite from austenite from martensite from bainite by any visual or other non-metallographic testing. A file will let you know that it is hard, but, believe it or not, coarse pearlite can skate a file if done nonchalantly.

The simplest test is filing along the edge with a sharp, newer file. It will slide on hardened steel. Some pearlite might resist, but adding some pressure to the file stroke will take metal off. Once you file the edge of a properly hardened blade, you will have no doubt what we mean when we say, "It feels and sounds like you are trying to file a sheet of glass."


Depending on blade size/thickness, you can usually quench quite a few blades in two gallons of oil before it warms up too much. There are several ways to cool down the oil if it gets too hot. About a 20° rise is all you should allow, so by 140°F, you need to let it cool off. You can grab lunch and let it cool on its own, or do a really neat trick. Put a couple 1 liter bottles of water in the freezer. When the oil gets too warm, take one and "stir" the oil pot with it. (Wipe off any moisture from the bottle first.) Just chuck the bottle in the trash when done.
 
I had some of the same questions about the "File" test as you did and how it would feel? I solved this by taking a decent quality knife w/a known hardness and running a file over the edge and then compare that to what it feels like on your treated blade before tempering and after you sand off the scale.
 
Stacy E. Apelt - Bladesmith said:
Once you file the edge of a properly hardened blade, you will have no doubt what we mean when we say, "It feels and sounds like you are trying to file a sheet of glass."

.
Click to expand...

One of the first things I noticed the first time I successfully hardened 1084 even before the file test was the sound the blades made when they clanked against each other. It is a MUCH brighter tone.
 
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