Tempering

[Sanith]

Looking around the forum I have seen allot of questions on the topics
of hot bending and tempering of picks. I know this is only my third
post but I have worked with the tempering proccess. The first step
in tempering metal is hardening. To do this you need to heat the metal
to aproximately 1,400 to 1,450 degrees F. (the diagram below gives
aproximate colors and corisponding tempertures on steel) then
quench the pick. I would recomend that this same temperture be used in
hot bending since it will harden the metal which is weakened in the bend.
Quenching can ethier be done in oil, water, or brine (salt water), these
are listing in order of increasing hardness yield. With hardening you want
to remember that the harder the more brittle. Thus, overheating say to
1,550 degrees and using a brine quench will yeild a hard but very brittle
pick. Also, note that since picks are very thin metal you try a
they will heat up fast and overheating will easily happen if you
are not careful. Practice a few times on scrap before pick that
you've invested alot of time in. The next step is called
tempering (ironic huh?) this step is to soften the metal to reach
the desired hardness. Before you do this bring your pick to a shinny finish
because tempering uses the "oxidation spectrum" of steel, instead of the
"illumination spectrum" used for hardening, you'll need clean the metal so
you can see the changes in color. The hotter the metal is heated the softer
the metal becomes and also the more flexible. I don't know what temperture is right for pick so you'll have to experiment. After heating let the metal cool slowly don't quench. Now if everything was done right you should end up with a stronger pick. Note: some metals such as saw blades are already tempered. Furthermore, this is a general method of tempering not all steels will reach the same to this process.

Here is the oxidation spectrum as it appears on metal. Temperture increases to the right

Here is a diagram of both spectrums and the coresponding tempertures. Diagram is from Reader digest "Back to Basics" book incase your interested which I doubt.

Sorry about the size of the pictures unforunately i don't know how to resize in bbcode.

[raimundo]

First, your piece of metal showing colors appears to be one of the stainless alloys which have a different set of colors from carbon steel alloys. A lot of picks are made from various carbon steel alloys. Many people feel the need to heat this metal before bending. It all depends on the temper of the metal you start off with. I usually bend cold and set the bend with a little heat from a bic lighter and quench it. Bending will work harden the metal a little, and heating with a bic lighter on a thin piece of steel for about 30 seconds to a minute or until cobalt blue color appears, is just to make the "memory" forget its former crystalization. Yes, thats right, heat after bending to set the bend. Next, when heating to very hot , some of the colors refered to in books like dull red, cherry red, white hot, are not the surface colors you will see after the metal has cooled, but the incandescense of the superheated metal. while straw yellow, and cobalt blue are from lower heat used on carbon steel for tempering. If you go hotter than cobalt blue, you will get a grey metal surface when you are done. If you quench in various oils you can get purples and even greens but these colors will not survive the handlling by fingers, they come right off .

[Sanith]

Yes i believe the metal i was using was stainless, or at least highly corosion resistant, (i do not know the specific alloy) however the colors do not differ greatly from those on 01 tool steel which is a "low alloy" carbon steel similair those used in picks (i believe another low alloy L6 "saw blade steel" is what alot of the pickmakers here use) not a "high alloy" carbon (yes stainless is a carbon steel people tend to think of carbon steel as "rusting steel") such as 440C Stainless which you refered to.

As for the idea of setting a bend by heating afterwards this can be done, though the metal should not be heated from the inside of the bend because it will cause the inside metal to expand faster than the outside and the bend may unbend slightly.

[stick]

Off topic, but long pictures and raimundo's posts don't mix well.

[Sanith]

Yeah as i said before i don't know how to resize in BBcode if anyone knows how to do this please post it here.

Also i made a mistake i double checked last nite because i thought i might have gotten this backwards you don't want to heat from the OUTSIDE of the bend inside is fine again sorry about this i should have double checked before i posted.