Heating 1084 for Hardening by color. Am I getting too hot??

Off topic. WOW what a difference 3m 984f ceramic belts make over Norton blue blaze. I spent 15 mins last night putting one side of the bevels on a blade and it only took 12 passes with this thing in 36 grit. SOLD!!! Wow what a difference. I just started liking making knives 10 fold. :eek:
 
Last edited:
Break some test pieces heated to the same color and look at the grain. If its too big, heat to a lower temp and repeat. I get/got decent results with this method, it just takes some practice and experience to hone in on the best color. Definitely not super accurate, but with limited equipment it was the best method I found. Well, coupled with a muffler and a magnet it was my best method.
 
Rick is right!
And i agree it's difficult to judge by color, especially if you have never had a comparison. For example your picture looks like too hot, but the butt of the knife has still some shadow from incomplete transformation...or could it be scale flaking?
If the forge is too hot your eyes will compensate for contrast and the camera will too.
 
I have been following this thread. I will give my eye-ball process.

Heat it as evenly as possible. Turn the blade over and over, spine up, edge up, side to side. Point the tip to the cool side of the forge to prevent overheating. Pay the most attention to the edge. That is the part you want to properly harden. The thicker parts at the ricasso will heat slowest, so put them in the hottest place.

Place a welding magnet on the forge somewhere near the front port.

As the blade starts getting red, pull it out and touch the magnet. If it sticks or grabs, put back in and heat higher. When the magnet stops sticking to the blade, note the color. Heat just a shade ( not a full color) redder. In my eyes, that is from a middle red to a light cherry red. If it is orange or yellow, it is far too hot. When the blade is heated just a but redder, I pull the blade and quench immediately. It is better to be barely above the non-magnetic than too much above the target temp. Most 1084 knife blades will harden sufficiently at 1450 F, so don't sweat it too much.

After five to eight seconds in the oil, I pull the blade out and straighten any warp/twist with gloved hands and/or a wooden mallet ( I call it a shwacker) on a 2X6 board that sits on the anvil. Until the blade reaches 400F, it is pliable and easily bendable.It is nearly impossible to break or crack while cooling from 900F to 400F. Once it starts to stiffen around 400F, DO NOT attempt to straighten anymore.

A side note on forge safety:
Staring into a hot forge for long periods can damage your eyes permanently. Wear UV/IR protection glasses ( Auralens AUR-99) when doing forge work. You can still learn to judge color wearing them, or remove them for HT, but wear them at all other times.
 
Stacy E. Apelt - Bladesmith said:
I have been following this thread. I will give my eye-ball process.

Heat it as evenly as possible. Turn the blade over and over, spine up, edge up, side to side. Point the tip to the cool side of the forge to prevent overheating. Pay the most attention to the edge. That is the part you want to properly harden. The thicker parts at the ricasso will heat slowest, so put them in the hottest place.

Place a welding magnet on the forge somewhere near the front port.

As the blade starts getting red, pull it out and touch the magnet. If it sticks or grabs, put back in and heat higher. When the magnet stops sticking to the blade, note the color. Heat just a shade ( not a full color) redder. In my eyes, that is from a middle red to a light cherry red. If it is orange or yellow, it is far too hot. When the blade is heated just a but redder, I pull the blade and quench immediately. It is better to be barely above the non-magnetic than too much above the target temp. Most 1084 knife blades will harden sufficiently at 1450 F, so don't sweat it too much.

After five to eight seconds in the oil, I pull the blade out and straighten any warp/twist with gloved hands and/or a wooden mallet ( I call it a shwacker) on a 2X6 board that sits on the anvil. Until the blade reaches 400F, it is pliable and easily bendable.It is nearly impossible to break or crack while cooling from 900F to 400F. Once it starts to stiffen around 400F, DO NOT attempt to straighten anymore.

A side note on forge safety:
Staring into a hot forge for long periods can damage your eyes permanently. Wear UV/IR protection glasses ( Auralens AUR-99) when doing forge work. You can still learn to judge color wearing them, or remove them for HT, but wear them at all other times.
Click to expand...

Stacy, thanks for chiming in. I really feel I got way too hot. I think I am going to set these aside until I have an accurate heating device in place, probably a gas forge and thermocouple set up on a PID control. My budget will be small, so I think I will get one of atlas's budget forgets and set it up with a muffle and PID and thermocouple and plumb in a small bypass to keep the burner running with a small flame when the PID shuts the solenoid on and off. With the budget forge PID and all I think I can come in under $275.00 Once I get set up better I will normalize these and try again. In the mean time I'll work better at checking with a magnet and going just slightly hotter.
 
The setup for a two-stage PID controlled forge is in the stickys. An Atlas forge can be controlled, but the burner will need to be the smaller one for HT. You can also make a small blown burner for HT.
 
So here is my test coupon done in the coldest form to how I did the knives in question. It's tougher than my what was harbor freight vice. Please let me know what you think of the grain size.



 
On the test coupon of 1084 I tested with tempering it back it snapped very easily in a vice with some little crescent wrench.


Sent from my iPhone using Tapatalk
 
Ghostman3 said:
On the test coupon of 1084 I tested with tempering it back it snapped very easily in a vice with some little crescent wrench.


Sent from my iPhone using Tapatalk
Click to expand...

This didn't bend very far, but after 2 hits with a 7 lbs sledge it broke my vice, brought it to my friends house who has an 8" forged vice and it took 8 more hits as hard as I could swing it. Think I'm just going to finish them out sharpen them up and do some cut tests. If it holds up good, I'll ride with it. I'll be paying better attention I my ht from now on.
 
pleasanthill said:
This didn't bend very far, but after 2 hits with a 7 lbs sledge it broke my vice, brought it to my friends house who has an 8" forged vice and it took 8 more hits as hard as I could swing it. Think I'm just going to finish them out sharpen them up and do some cut tests. If it holds up good, I'll ride with it. I'll be paying better attention I my ht from now on.
Click to expand...

Wait, it took eight hits with a 7lb sledge to break your hardened test piece?? Did you temper it first or something? Should have broken WAY easier than that...
 
You must log in or register to reply here.
Back
Top