A little confused on heat treating and normalizing

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fateofone

Joined
Sep 21, 2016
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25
Hello everyone. So I understand how to heat treat and normalize and all that good stuff, but I had a couple questions: for 1, I am using an old leaf spring for the steel. I know it's high carbon because when grinding, the sparks go everywhere and all that good stuff. But I wanted to make sure that heat treating it as if it's 9160 will probably be fine.

Second, I was using an old charcoal furnace to anneal it, and let's just say I have to normalize it because I screwed up. So I'm going to make a gas forge instead, but I just don't really get how people use these things without thermometers. Do I just continuously touch the blade with a magnet to make sure? I guess I just don't get it because the forge will just get hotter while the blade is in there. Is that okay? Just as long as the blade itself doesn't get much past non-magnetic temps?

Also, I read to quench, you need to use hot oil. Is that true? I thought the whole point was to quickly bring it down to a lower temp.
Anyway, thanks for any answers.
 
I can answer question 2 and 3. Not sure about the first one. As far as telling when a piece of steel reaches critical many folks do use a thermometer, or some other way of digitally controlling the temperature. If you are like me though and are trying to do it it by eye, you start off with a magnet, but after awhile you will get an eye for telling when you are there, and will no longer need it. It just takes practice, making lots of knives.

There are a lot of variables involved in heat treating even known steels. If you quench in cold/room temperature oil you may shock the steel causing it to crack or warp, similar to what you might get quenching in water. The temp of the hot oil should only be about 120 F or so.
 
I use magnets to tell heat of the steel as well, though some steels take a little time past magnetic or a (soak) and that's near impossible without digital control.
 
fateofone said:
Hello everyone. So I understand how to heat treat and normalize and all that good stuff, but I had a couple questions: for 1, I am using an old leaf spring for the steel. I know it's high carbon because when grinding, the sparks go everywhere and all that good stuff. But I wanted to make sure that heat treating it as if it's 9160 will probably be fine.

Second, I was using an old charcoal furnace to anneal it, and let's just say I have to normalize it because I screwed up. So I'm going to make a gas forge instead, but I just don't really get how people use these things without thermometers. Do I just continuously touch the blade with a magnet to make sure? I guess I just don't get it because the forge will just get hotter while the blade is in there. Is that okay? Just as long as the blade itself doesn't get much past non-magnetic temps?

Also, I read to quench, you need to use hot oil. Is that true? I thought the whole point was to quickly bring it down to a lower temp.
Anyway, thanks for any answers.
Click to expand...

Why you annealed leaf spring ? If it is not too thick you can easy file with metal file or on belt grinder , and then quench ? You do not put magnet inside forge you're gonna ruin it . First look on color , when start to became red take blade out and try with magnet .......
 
Natlek said:
Why you annealed leaf spring ? If it is not too thick you can easy file with metal file or on belt grinder , and then quench ? You do not put magnet inside forge you're gonna ruin it . First look on color , when start to became red take blade out and try with magnet .......
Click to expand...

I'm hoping it goes without saying that the magnet isn't going in the forge. Haha
 
The temperature of the oil will likely have very little difference regarding stressing the steel. A temperature difference on only 70° is hardly going to make a difference to a bar of steel at 1500°... it, may, however, affect that oil's ability to properly cool a piece of steel quickly enough. Still, read the instructions for the quenching oil you're using to determine if it's necessary to heat it.

There's a fantastic sticky on heat treating threads here on BladeForums. I would HIGHLY advise all of you guys to peruse them. Any and every question that's been posed here is answered within. :)



CrookedPath said:
I can answer question 2 and 3. Not sure about the first one. As far as telling when a piece of steel reaches critical many folks do use a thermometer, or some other way of digitally controlling the temperature. If you are like me though and are trying to do it it by eye, you start off with a magnet, but after awhile you will get an eye for telling when you are there, and will no longer need it. It just takes practice, making lots of knives.

There are a lot of variables involved in heat treating even known steels. If you quench in cold/room temperature oil you may shock the steel causing it to crack or warp, similar to what you might get quenching in water. The temp of the hot oil should only be about 120 F or so.
Click to expand...
 
I doubt you will crack steel in oil. Warm oil is thinner, thin oil is faster. Canola oil should be 120 degrees or so for 1095-1084-W1-W2 and maybe for 5160-01.

The stickies are a good read!
 
Cody Hofsommer said:
I doubt you will crack steel in oil. Warm oil is thinner, thin oil is faster. Canola oil should be 120 degrees or so for 1095-1084-W1-W2 and maybe for 5160-01.

The stickies are a good read!
Click to expand...

This is correct^
And please do read the stickies, lots of knowledge in one place.

CrookedPath said:
....There are a lot of variables involved in heat treating even known steels. If you quench in cold/room temperature oil you may shock the steel causing it to crack or warp, similar to what you might get quenching in water. The temp of the hot oil should only be about 120 F or so.
Click to expand...

That's just not true. Like Cody said warm oil (not hot) is actually faster than cold oil. The problem with cold oil is that, depending on the oil, it might not quench fast enough.
 
My bad. I did not mean to spread incorrect knowledge. Can't say where I read that info, maybe iforgeiron? Any way, thanks for the corrections.
 
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