PetrifiedWood
Well-Known Member
I want to be reasonably sure that I am doing a correct job of heat treating. I spend several hours here a couple of days ago reading through the HT section and it seems like the more I read, the more confused I became.
I have a 27" Evenheat kiln with a Rampmaster controller. It's new, and has only had a break-in run, and one live run with a 1/8" A2 knife.
What I want to know is, can I trust that if I set a temperature and time program in the kiln that corresponds to the steel manufacturer's instructions, will the steel be properly hardened?
I have some O1 on hand and that's going to be the medium for my next several knives. I have read all kinds of arguments for and against a range of different oils, and different oil temperatures.
I also want to know why it's so important to temper immediately. I've heard that internal stresses in the steel can cause it to crack, and that quickly tempering can prevent this from happening. But it seems to me that if a knife is going to crack it will happen in the first minutes after quenching. Has anyone had a blade crack on them several hours after quenching that was fine for a few hours after?
The reason I ask is that in order to achieve some of the tempering temperatures I'd like to use, I might need to use my kiln. It would need to cool to a suitable temperature first, and that takes time. Enough time that I don't think it qualifies as "immediately". So I want to know what happens to the steel after it's been quenched and before tempering that can be avoided by tempering immediately.
Also, I read a really old post by a guy who has an evenheat and was measuring a different temperature at the top and bottom of his oven opening. The only way I have to measure temperature in my kiln is by trusting the thermocouple and controller readout.
I had hoped to eliminate the guesswork and experimentation by getting a kiln. If guys with a coal forge and a magnet can get good consistent results, surely a temperature controlled kiln should be able to produce the proper results?
For example, my A2 program involved placing the blade in the oven cold. Then ramp up to 1500 and hold for 30 minutes. Then ramp up to 1800 and hold for 30 minutes, then I removed it from the kiln and hung it up to cool in my shop. I then tempered at 550 degrees when it was "hand warm" for 2 hours. Let it cool to "hand warm" and tempered again for 2 hours. I was shooting for a rockwell C of 58 to 60. I have no way of measuring hardness.
So I have to trust that the steel manufacturer's instructions will allow me to achieve that hardness if I follow them exactly. But my reading has shaken my confidence that my equipment is accurate enough to be trusted.
Any thoughts?
I have a 27" Evenheat kiln with a Rampmaster controller. It's new, and has only had a break-in run, and one live run with a 1/8" A2 knife.
What I want to know is, can I trust that if I set a temperature and time program in the kiln that corresponds to the steel manufacturer's instructions, will the steel be properly hardened?
I have some O1 on hand and that's going to be the medium for my next several knives. I have read all kinds of arguments for and against a range of different oils, and different oil temperatures.
I also want to know why it's so important to temper immediately. I've heard that internal stresses in the steel can cause it to crack, and that quickly tempering can prevent this from happening. But it seems to me that if a knife is going to crack it will happen in the first minutes after quenching. Has anyone had a blade crack on them several hours after quenching that was fine for a few hours after?
The reason I ask is that in order to achieve some of the tempering temperatures I'd like to use, I might need to use my kiln. It would need to cool to a suitable temperature first, and that takes time. Enough time that I don't think it qualifies as "immediately". So I want to know what happens to the steel after it's been quenched and before tempering that can be avoided by tempering immediately.
Also, I read a really old post by a guy who has an evenheat and was measuring a different temperature at the top and bottom of his oven opening. The only way I have to measure temperature in my kiln is by trusting the thermocouple and controller readout.
I had hoped to eliminate the guesswork and experimentation by getting a kiln. If guys with a coal forge and a magnet can get good consistent results, surely a temperature controlled kiln should be able to produce the proper results?
For example, my A2 program involved placing the blade in the oven cold. Then ramp up to 1500 and hold for 30 minutes. Then ramp up to 1800 and hold for 30 minutes, then I removed it from the kiln and hung it up to cool in my shop. I then tempered at 550 degrees when it was "hand warm" for 2 hours. Let it cool to "hand warm" and tempered again for 2 hours. I was shooting for a rockwell C of 58 to 60. I have no way of measuring hardness.
So I have to trust that the steel manufacturer's instructions will allow me to achieve that hardness if I follow them exactly. But my reading has shaken my confidence that my equipment is accurate enough to be trusted.
Any thoughts?