How to heat treat 4340 steel and 4140

[@hipjazzbone]

I use vegetable oil with 1095 and O1. Would vegetable oil work with 4140? Do you need to temper after hardening?

[@lumichael4566]

Looks like pretty cool. And if you guys wanna get more information about 4340 steel and 4140 steel, the links as below
4140 steel:steelpurchase.com/4140-scm440-17225-steel/
4340 steel:steelpurchase.com/4340-sncm439-16563-steel/

[@zadeify9596]

I recently started hammering a cleaver from a spindle steel. I just wonder how to heat treat it to make it good enough for a present for someone.

[@mannsdan]

any idea what the hardness rating was after the quench? could you skate a file across it?

[@AllodialTitle]

Motor oil can contain metal contaminates.

[@luciusirving5926]

I use mineral oil for chromoly chisels.

[@speedxdreems]

lol,