At a flea market this morning, I picked up several pieces of a tool steel marked "Firth-Sterling Circle C." 6 of them are 1"x1"x7" and one is 3/4" x 3/4". My understanding is the previous owner was a gun smith.

I'd like to try my hand at making a small hatchet and thinking some might be usable as a forge welded cutting edge, but before experimenting with an unfamiliar material, I'm wondering if anyone has had experience working with and heat treating this material? Looking for ideal quench medium/heat treating conditions and any other advice on it's practical uses.

Have you done a web search? The maker will have the characteristics and intended uses of steel posted. Some steel isn't forgable or requires sophisticated equipment to heat treat, etc. 

Not having the maker's data it comes down to doing the mystery metal tests to determine what YOU can do with it. There a lot of guys on the forum that routinely do things with steel types I'd find a real challenge. 

Wish I could be more help.

Frosty The Lucky.

I didnt have any trouble finding this, I hope you have a power hammer

Looks like a high alloy tool steel to me; hard to work and very picky to heat treat---computerized control inert atmosphere electric furnace suggested. Wouldn't expect it to forge weld easily too.

Sounds like large lathe bits. I believe I have seen Firth Sterling on some of the HSS tool bits I have for my lathe. If it is HSS (high speed steel) forget using it for anything but what it was intended for. The do make good parallels for milling.

GoogleFu RULES! 

Man that stuff's a witch's brew! Better someone else's stock, I have all the lathe cutters I'll ever need.

Frosty The Lucky.

I searched Firth Sterling lathe bits and got a ton of hits for Circle C

Thank you for the responses. Sounds it won't be particularly productive to tinker with this stuff within the context of blacksmithing. If anything, it was enlightening to read up on alloy composition a bit. Found the chart this morning but didn't know what I was looking at until I reacclimated with the periodic table. Witches brew indeed.

I might play with a piece of it out of curiosity, but more than likely I'll just cast off the majority into seas of eBay. I payed $10 for the lot and it looks like it could fetch enough to trade up to something more useful.

You're not the only one to get a good deal that turned out to be good for something else. I have a stack of planer blades that I can't dent at high yellow. Then there are the coffee cans of worn out and broken drill bits I was going to include in billets but . . . 

My Father was a metal spinner and machinist and sent me home with two Kennedy top boxes packed solid with lathe cutters and a couple boxes of instruments. I tried forging a lathe cutter once but it wasn't a fail like the planer blades I might give it another shot one of these days.

If you're at this for a while you'll have LOTS of good deals that didn't quite work and every once in a while one of those will turn out to be PERFECT for something else.

Frosty The Lucky.