Drill rod commonly comes in two flavors . W1 water hardening and
O1 oil hardening . W1 is cheaper , O1 is more flexable in procedures
. There is a third alloy which is called “Versalloy” which is more
easly machined than O1. Quenching fluids used have run the spectrum
from water, salt water, stale beer, urine,blood and oil . KISS, Keep
It Strictly Simple . Another product which needs mentioning is
call case hardening compound ,"Casenite " by name . For items which
don’t need great tensil stregenth, then mild steel can be "case
hardned " Its not expensive . Try McMaster Carr. If You’ve got
further questions call me at - @rlpowell . KISS and be
carefull. RLPowell