Opinions on steel that I can heat treat at home

outlandish710 said:
Can you write a bit more about why checking for glow color when the TC is placed directly on the steel would not give accurate results?
Click to expand...
human perception is very relative. how you see a colour will be dependent on the other colours around it, lighting, your expectations of what the colour will be. Our brains just don't work in a way that generates accurate readings of the world.
IMO, you can get around this with a l o t of practice (years, decades? i'm testing this), but if you're just interested in getting a precise result it's easier to use a thermometer of some type.

Edit: here's a shade perception visual illusion as an example
B-2wAF5VIAA63a6
 
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That would be one pricy muffle tube with a .25"X2"X12" bar of copper. Thats around $50. - Just kidding, that would certainly make for even heating of a blade laid on it.

When doing a forge HT, I use a square 3" wide schedule 80 stainless pipe with walls .300" thick. It evens out the heat nicely. It cost just a few bucks at the scrapyard.
I have stuck a long TC in the pipe and got fairly good readings. I bent the 8-gauge wire ends down at 90° and had the TC block below any flames or heat.
In the absence of an oven it works well enough.

I don't think a clay coating would stay on long, though. Have you tried it?
 
stainless is great for this but I just use whatever scrap I find - usually round tubing shaped on mandrels, depending on size of the respective blade - with clay it doesn't burn through.
said clay is a watered down yaki ire mix; clay, fine sand and charcoal. if the muffle is not agitated too much there's a good chance the clay will stay in place. the best adhesion, like with knives during traditional yaki ire, is achieved by cold application and letting it dry for at least a day. but in a pinch several thin layers applied hot also works. just not too hot or it wont stick at all.
the copper is only .12" / 3mm thick - flattened scrap copper pipe. once I shut off the forge I immediately quench it in water, to avoid oxide formation.
opposite for cheap thermocouple. slow cooling or the thin wires tear themselves apart at the joint. twisted together lasts longer than welded.
 
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Sounds interesting. I don't forge HT much anymore, but if I do it again, I'll have to try a clay coating on the muffle.
 
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