Tempering?

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Is it possible to quench and temper some small parts with an oxy torch? I am going to machine some parts from annealed 4140 and was wondering if I can quench and temper it to harden it.HTP Invertig 201Lincoln Idealarc SP250Miller 180 AC StickBy farmall:They should have held the seagull closer to the work, squeezing evenly for best deposition.
Reply:It is possible but you will need to eyeball the whole process. If just want to make it harder than it is in its annealed state it will be easy, but keep in mind that you could make it brittle as well. If you need to get it to a certain RC hardness, you are better off doing a controlled heat treatment with an electric oven so you can precisely set the temperature, soak time and such.I make knives out of leaf springs just as a hobby and I use a coal forge as heat source and old motor oil as quench medium... but if you want to do it the right way, this is not the way to go.Mikel
Reply:The quench is what hardens 'hardenable' steel.Tempering then softens and 'toughens' the formerly hard-but-brittle steel.Sure, you can use an oxy-fuel torch to heat 'small' parts to quenching temperature (which varies a bit with the exact alloy of the steel you are working on).  Also note that some steels are supposed to have heat-rate limits and soak times at certain temperatures as well (for things like the grain structure and not cracking the part if it is a 'complex' part due to differential heating expansion effects and so forth).Tempering 'small' stuff can often be done in a typical household oven or such.  Bake at 350F for one hour.    The best laid schemes ... Gang oft agley ...
Reply:Hmm, well I am sure the 4140 in its annealed state would be just fine for me, but I was thinking it would be nice to toy around a bit and try and strengthen the material.. I would hate to make it brittle though...Funny you talk about the knives, I am working on one from a leaf spring as we speak! My first one.Well  I will machine the parts and go from there... Maybe just look for some normalized material. Attached ImagesHTP Invertig 201Lincoln Idealarc SP250Miller 180 AC StickBy farmall:They should have held the seagull closer to the work, squeezing evenly for best deposition.
Reply:Originally Posted by fordmanFunny you talk about the knives, I am working on one from a leaf spring as we speak! My first one.
Reply:Another combination you might consider depending on the size and shape of the items you are dealing with... is the method for selective speed and depth of hardening ( and by definition annealing at the same time ) used by traditional Japanese sword makers....   This involves painting multiple layers of clay slip onto the item.... the thickness of the slip determining the speed of quench the metal is subject to.   They might use one layer on the actual sharp edge... then two starting an eighth of an inch back from the edge..... and so on... this gives in one quench a variable hardness from the cutting edge to the back of the main shaft with ductility remaining in the main shaft ( what we call toughness ).....    I saw this on a PBS show... probably NOVA ... you might can find it for viewing...Last edited by GBM; 11-17-2011 at 05:39 PM.Weldandpower Lincoln 225 AC,DC with Briggs 16hp gas engine.WW2 era Miller TIG.
Reply:Originally Posted by GBM...the method for selective speed and depth of hardening ( and by definition annealing at the same time ) used by traditional Japanese sword makers....
Reply:Originally Posted by Mikel_24Holly crap. That knife IS NOT for food prep... thats for sure. XD XD
Reply:Originally Posted by fordmanObviously I dont have a way to really measure the temp....