tempering after waiting too long...

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vikingGoalie

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So of course I didn't read about the process until afterwards :| I knew that the steel was brittle after the quench and that you have to be careful with it and temper it.
I didn't know that it was important to do that tempering as soon as possible after the HT
But i have 2 knives i'm making out of 1080, I did a heat treat on them both quenching in canola oil.
File skated on the one but i'm iffy on the other.

but what i did not realize at the time is that you need to do the temper right after it cools down from the heat treat. I didn't do that, nothing has cracked or anything like that.
Can I proceed with tempering on the blade that I'm pretty sure heat treated right? Or... should i heat treat it a second time before going to the oven?

Also the first blade I got up to a little past dull red throughout and I'm iffy on whether that was hot enough (leaning towards no). So for that knife can I just heat treat it again or do I need to do something with this steel before doing that a second time?
tx
 
what about the blade that i think needs to be heat treated a second time? should i temper it first or can i just heat treat it again. tx!
 
If you plan on hardening the knife a second time, there is no reason to temper it first. Just re heat treat it.
 
If you go on Amazon and search for this

Markal Thermomelt Temperature Indicator Heat Stick, 1650 Degrees Fahrenheit​


This is what I used when I was heat treating in a forge, it helped me tell if I was close to the right temperature. Just look for the temperature heat stick you want to heat treat your 1080, I think I used 1550 degrees stick.
 
so i just re-heat treated both blades, the first one I was 100% sure i had not gotten it hot enough.
So this time I had a welding magnet handy so that when it no longer had any attraction to the magnet I'd know i was at the right temp.
First blade went really well. I get it to that point put it back in the forge just a tick longer and then quench in canola oil. No warps, file skates on it. Perfect.
Then I look at the second blade which i already tempered, and I started doubting my HT because the color i got it too previously when heating it up was not to the point this blade was at.
(I didn't use a magnet the first time) So I said screw it and threw it in the forge to re-do the heat treat. Same drill, got it to non magnetic put it back in the forge for maybe 30 seconds longer and quenched.
And.. got a minor warp. so i put both in for tempering and after the first go I tried to straighten the warp by using a vice and a few bolts off set to help bend it back. that worked mostly but there's still a small wobble in the spine,
which is odd because the edge didn't warp at all that i could tell. I think it's kinda "good enough" but we'll see what i think after I sleep on it ;) Not sure the best way to deal with a warp so i just winged it.
Kinda mad at myself because most likely the first HT was fine, but I think i got the metal harder the second go around so dunno. When i figure out how to actually share pictures here easily I'll put some up.

I did the temper cycle at just over 400F for an hour, let it cool and back in again twice, and I did that right after it cooled down from the heat treat.
 
Nonsense, salt melts, it does not break the bonds of the sodium and chlorine.
 
vikingGoalie said:
Not sure the best way to deal with a warp so i just winged it.

I did the temper cycle at just over 400F for an hour, let it cool and back in again twice, and I did that right after it cooled down from the heat treat.
Click to expand...

experience will help you deal with warp - in terms of what you do before heat treatment, how you heat the steel (evenly is important - by eye, by color, etc, and for the same amount of time if you can help it), and how you quench and deal with warping.

You'll learn to manipulate hardness a little bit, too, by choosing how fast the top end of the quench goes (the first few seconds) and how cold and how fast you get to cold on the tail.

Observe and test things, and when you cut steel from bar or have cutoffs, note the grain orientation and then save those because you can test little routines with small pieces very quickly, temper them, note how much force it takes to break them and then look at the fineness of the grain under a cheap (like $20) handheld USB scope.

My advice is different than others' advice in some cases. I like to heat quickly, avoid anything over critical prior to the quench heat, heat evenly and overshoot temp just a little bit, especially if the steel doesn't mind it. This overshoot on temperature has to be quick though, like 10 seconds, not 10 minutes. Then, try variations of things to learn to manipulate what you're doing, save the results and refine.

I guess if you want to forge heavily, to do this with good rolled stock will serve you well, and then if you're forging, you'll have a good baseline result to compare to. Larrin has showed pictures of coarse grained samples that people have sent to him - I think they were trying to be a hero with the forging. I've had a couple of bad results, but the alloys I use a lot, the results are just as good or better than commercial. I put in the time on the two that I use to snap samples and test results, though, and where I haven't done that, varying success (all the way down to unsuitable) can be the result.
 
vikingGoalie said:
So of course I didn't read about the process until afterwards :| I knew that the steel was brittle after the quench and that you have to be careful with it and temper it.
I didn't know that it was important to do that tempering as soon as possible after the HT
But i have 2 knives i'm making out of 1080, I did a heat treat on them both quenching in canola oil.
File skated on the one but i'm iffy on the other.

but what i did not realize at the time is that you need to do the temper right after it cools down from the heat treat. I didn't do that, nothing has cracked or anything like that.
Can I proceed with tempering on the blade that I'm pretty sure heat treated right? Or... should i heat treat it a second time before going to the oven?

Also the first blade I got up to a little past dull red throughout and I'm iffy on whether that was hot enough (leaning towards no). So for that knife can I just heat treat it again or do I need to do something with this steel before doing that a second time?
tx
Click to expand...

That ain't how it works.

I know you want to design knives for e-commerce, but there's a lot of balderdash, blatherskite, and boloney out there about making the damn things, so I'm gonna help you out and tell you how it's done:

First thing, you head on out on a clear sky day and you look at the sun exactly 2 hours before sunset. Just have a good long stare at it. That's the color you want for quenching. Not an hour before, not an hour after.

Next, you gotta pick the right steel, and that's a lawnmower blade. Not just any lawnmower blade, is has to be a John Deere mower blade or it ain't gonna work right. That blade better be used, too, so it's been good and jiggled. You gotta make the far end of the mower blade the tip of your knife, because most of the carbon gets spun out there when the blade's jigglin'.

Now once you got that blade heated up to the color you seen in the sun, you gotta quench it, and nothin' better for quenchin' than a cold, flowing creek. It's gotta be flowing. Just toss it on out there, and fish it back with a magnet on a string.

You get that right 500 times in a row and then maybe, maybe, you'll be ready to make a knife for e-commerce worth a damn.


8SJWZAn.gif
 
D-weaver said:
experience will help you deal with warp - in terms of what you do before heat treatment, how you heat the steel (evenly is important - by eye, by color, etc, and for the same amount of time if you can help it), and how you quench and deal with warping.

You'll learn to manipulate hardness a little bit, too, by choosing how fast the top end of the quench goes (the first few seconds) and how cold and how fast you get to cold on the tail.

Observe and test things, and when you cut steel from bar or have cutoffs, note the grain orientation and then save those because you can test little routines with small pieces very quickly, temper them, note how much force it takes to break them and then look at the fineness of the grain under a cheap (like $20) handheld USB scope.

My advice is different than others' advice in some cases. I like to heat quickly, avoid anything over critical prior to the quench heat, heat evenly and overshoot temp just a little bit, especially if the steel doesn't mind it. This overshoot on temperature has to be quick though, like 10 seconds, not 10 minutes. Then, try variations of things to learn to manipulate what you're doing, save the results and refine.

I guess if you want to forge heavily, to do this with good rolled stock will serve you well, and then if you're forging, you'll have a good baseline result to compare to. Larrin has showed pictures of coarse grained samples that people have sent to him - I think they were trying to be a hero with the forging. I've had a couple of bad results, but the alloys I use a lot, the results are just as good or better than commercial. I put in the time on the two that I use to snap samples and test results, though, and where I haven't done that, varying success (all the way down to unsuitable) can be the result.
Click to expand...
Wouldn't you want to go above critical for normalizing the steel though? I mean I can see maybe doing a sub critical anneal after that, or maybe thermal cycling below critical (idk, what kind of effect that would have).

Really I'm just wondering why you stay below critical before austenizing, and quenching? Are you doing stock removal, or forging?
 
Nonsense, while molten salts typically have high boiling points, their crystal lattice structure and associated bonding network has been lost. Molten salts do however have significant short and medium range order due to the strong interactions.

(not sure who or what we're responding to but it's fun to shout nonsense on a Saturday morning)
 
The answer is bath salts. What you do is coat the blade in bath salts, then smell the vapors while it's gradually heating up. The smell of the molten bath salt vapors will tell you when to quench the blade.
 
Mecha said:
The answer is bath salts. What you do is coat the blade in bath salts, then smell the vapors while it's gradually heating up. The smell of the molten bath salt vapors will tell you when to quench the blade.
Click to expand...
Idk I think it's hard to find bath salts now days. The whole Florida man incident kinda made those hard to get a hold of.
 
Ahh the worst super hero ever.
If you are unaware of Floridaman's power, go to his website. Yes there is a .com bearing his name. It's great.
 
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