Hardening and Tempering

Still air should be ok, don't need to use an air blast, at least for normal knife/plane blade/scraper sections. A2 should perform much better than 01 for shaving reed blades ("much better"=factor of 4 or 5 edge holding). This is dependant on a good heat treatment though: there is a huge dip in the torsional impact strength curve of A2 when plotted against the tempering temperature. In other words, don't temper it too hot, or it gets brittle. Try a tempering temperature right around 400 degrees (F), that should be safe. Temper it at least twice, and soak for a good long time (like two hours) at the tempering temperature. A sub-zero at dry ice temperatures after hardening, and before tempering is beneficial, but not absolutely mandatory. Harden between 1700 and 1800 (F), if you can preheat at 1450, do so. Keep the hardening period down to about 10 or 15 minutes or so (preheat can be longer).

Try it, you'll like it.

Adam Smith Midland, Ontario, Canada

see

John Major (b. 1943), British Conservative politician, prime minister. Quoted in: Observer (London, 7 July 1991).

Nice site, George. I bookmarked it. Thanx,

I quench my air-hardening steel blades between .5" aluminum plates. Bring the blades out of the furnace at critical, slap them on a plate, clamp the other plate on top, wait a few minutes. No warp that way.

If there is time and I'm not doing a big batch, I'll freeze the al overnight. Gives a more rapid quench.

-Frank

Frank,

Thanx for sharing the beautiful pix of your craftsmanship. Truly outstanding ! Your aluminum-quench of air-hardening steel is very interesting and offers a great suggestion for avoiding warpage in thin pieces during quench. But what about tempering after the aluminum quench ? Do you use conventional temperature indicators (colour or crayon sticks, etc) for temperature sensing in the tempering process ?

Bob (frustrated heat treater from way back) Swinney