Greetings, Ok, yesterday I put into practice a bunch of tips and ideas. Still using charcoal, can't use coal in the city and haven't made a Reil-style propane burner yet.
Playing with drill rod. Heat treated a little spoon carving gouge I forged with a propane torch. The shaft sagged in the fire. OK, no problem, now it's a bent spoon carving gouge. Onward to the next object, a scraper burnisher.
Instead of whining about the sag, I got a 1/2 X 8 black iron nipple and end cap. The fire was Kingsford confined by a few bricks and some clay flower pot shards. Blower was a hair drier. Tuyere was 1/2 pipe stuck in the side. Wasted fuel, but the nipple and the 1/4 drill rod length inside got to the right temp.
Couldn't see the arrest point light show because the rod was in the pipe. Doh. Got to the color above the arrest point that I learned from the sagging rod's heat, when I did see the AP (Alvin Point) phase change.
Sprung for a jug of rapeseed oil at the grocery. Heated the oil to
100 degF. Amusing side-note: a 1/4" circle at top end of the glass bulb of the candy thermometer had popped off when I laid the thermometer aside during a heat last winter. As I was stirring the oil, I saw a spider inside, running up and down the paper temperature scale. It was there the whole time, and AFAIK, is still in there, happy as can be.Put a pizza stone in the oven. Made a little foil tray, filled with enough Wesson to cover the workpiece. Heated the oven, stone, and oil pan to 400 degF while messing with the forgelet.
Pulled the rod out of the nipple with tongs One Mississi and into the oil lengthwise. Stirred it around until the wild action stopped. The interface layer between the bulk oil and the rod was apparent.
Sometime in the last few days I saw, somewhere, someone cooled his work further in water. This is something I should not have heeded. I swished the rod in a bucket of water before wiping it down.
Placed the rod in the hot oil waiting in the oven and forgot about it for an hour.
Chucked it in the DP and polished with silicon carbide papers to 600 grit, then wiped my green honing strop over it a while. Pretty, pretty.
Tried out my new scraper burnisher on some Clifton scrapers. The rod gets scratched. Under a 5x loupe I see longitudinal cracks. Rats.
The handle end of the rod, which was at the open end of the nipple during the heat, and which never got real hot, has the warts I imagine are patches of martensite which have a larger volume than the regions of austenite & friends that didn't change phase.
This object still works for its intended purpose. It works much better than the side of my #2 phillips to turn scraper edges. I am reluctant to put in in the vise and whack it to see what's inside. With that said, what sayeth the gurus? Volume changed inside, and the chewy center cracked the crunchy outside?
later,