Normalizing a blade

JAGMAN · Post by **JAGMAN** » Wed Feb 25, 2004 3:47 am

Hi there Bill and other metalergists out there, I have been working on a siletto blade trying to relocate the locking pin hole, I welded up the origional hole with stainless steel (tig) and then ground off the excess and this worked out fine, the blade got a little hot and after the weld it was blue and brown around the work area. When I went to drill the relocated hole the blade is still very hard to drill and I ended up having to use a carbide bit. My question is this - can I heat the entire blade with my oxy - acetylene torches to normalize it, carry out the rest of my work without breaking all my drill bits and dulling my files, then re-harden using the gas?
Would I heat it to cherry red and let it air cool down, should I hang the blade or lay it flat, and finally if it is possible using gas, could you outline the steps to re-temper. Thanks in advance,
Jagman

Post by **Bill DeShivs** » Wed Feb 25, 2004 5:14 am

I really can't help here, as I have never tried retempering 440 B.
You could do a search on heat treating. 440B may be an air-hardening steel, so normal heat treating procedures won't work if it is.
Please let us know what you come up with! This will be an interesting thread.
Sorry,
Bill

Post by **Bill DeShivs** » Wed Feb 25, 2004 6:07 am

I was able to do a little research on this subject.
440B and 420 heat treat like 440C. You should be able to heat the blade to about 1900 degrees and hold it there for a few minutes. Then air cool.
Reharden the same way, with an oil quench. I would temper in a toaster oven at about 230-240 degrees for about 20 minutes.
Remember-other than red, stainless does not show colors as well as carbon steel, so you need an accurate toaster oven to temper.
Bill DeShivs

Vagrant · Post by **Vagrant** » Wed Feb 25, 2004 7:22 am

I've totalled 3 toaster ovens [one way or another] over the last 30 years. I always find the next one at the dump. Never spent a penny on one. They last a looong time even with the way I abuse them ! You gotta love 'em. [I did get one for the house at an auction $5].