Hardening and Tempering

I have some "experience" with tempering and hardening steels using water or
oil as the quenching medium in my home shop. Have never tried air hardening
steels; what is the method of quenching?
Leave it in air to cool after the piece has been heated to hardening
temperature, or use an air blast for quicker cooling?
What method is used for tempering temperature control (as in water
quenching, using the colour as temperature indication)?
Would there be any benefit to using air hardening steel over oil hardening
steel for wood cutting blades 3/4 inch wide by 3/16 inch thick, used for
(commercial) shaving of reed blades (oboe, sax, bagpipe)?
All helpful comments appreciated.
Ray
Reply to
Ray Field
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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
Reply to
Adam Smith
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Unka' George (George McDuffee) .............................. Only in Britain could it be thought a defect to be "too clever by half." The probability is that too many people are too stupid by three-quarters.
John Major (b. 1943), British Conservative politician, prime minister. Quoted in: Observer (London, 7 July 1991).
Reply to
F. George McDuffee
A bit off topic, but you are clearly a resource willing to share. Would this recipe apply to springs too? Could I form the spring then harden and temper? Thanks, Bob
Adam Smith wrote:
Reply to
gwpm57
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
Reply to
Frank Warner
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
Reply to
Robert Swinney

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