Machinist

[Lawrence London <lfljvenaura@gmail.com>]

Q:

Help identifying tool steel
Only markings I have are E93909 and RH 4-2
1/2 and 5/8 hex bars. Originally bought to make stone chisels. Need to identify so I can properly harden.
How much trouble will I be in if I oil quench and then draw back?

A:

That is exactly what I would do. First you have to assume it is oil hardening (something of a guess here). Heat it up until a magnet will not
stick to it (bright cherry) and plunge it vertically in a fairly large container of oil with a lid just in case the oil ignites. Check with a
file to see if it is hard as woodpecker lips. Polish one side with a cratex wheel, course steel wool, or whatever you have that will do the job
to remove the fried on oil. The oil I use is generally not very clean so this may take a little effort. Heat the hammer end very slowly. Don't
put the flame right on the metal or you will miss the bus when the colors start to run. Hold the flame maybe six inches away and be patient. You
don't want the color bands to be too far apart however because the business end may get hot enough to temper before the hammer end has softened.
Adjust your heat so the bands are about one to two inches from straw to blue. When the cutting edge is a dark straw then quench again quickly and
swirl it around. Now if it is oil hardening and you did everything right it should make a fine chisel. If not then try water or brine.


--

Lawrence F. London, Jr.
lfljvenaura@gmail.com

https://sites.google.com/site/avantgeared