Question on heat treating

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fivefold

Joined
Mar 29, 2008
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Anyone have any info/preferences regarding how much metal should be left on the edge prior to heat treating? I would imagine that you wouldn't want to take it down to a razor edge because of warping issues. Any help would be greatly appreciated. Thanks.
 
I usually leave about 1/32 or a little less and haven't had much trouble with warping since I started going to that thickness. On the other hand, since I finish all with hand tools, it takes 2 to 3 hours with the stone to get an edge when you start with the edge that thick. With power tools it might go faster.
 
If you use a complex steel like S30V you will leave as little as possible as it's a bear to work in the hardened state ! It's best to stress relieve or normalize after grinding to minimize warping.You do put stress into the steel when grinding which may cause warping.
 
I've gone as thin as .010" on D2. It can warp a little bit, but that can be fixed at around 400-500 before the quench is finished. I'm trying to avoid any grinding at all after HT.
 
I usualy go around .010, to .015. Almost to finished thickness before the edge. nearly all my blades are very slightly convex ground though.
 
What about something like 1060 or 5160(aka trucksping), I have an 18" chopper that needs heat treating soon and the edge is about 45-50thou... probably could take it down a bit? I thought I would leave a bit more meat, as its going to be heated in a charcoal bed, so I don't want to risk over heating it.
 
john0270 said:
What about something like 1060 or 5160(aka trucksping), I have an 18" chopper that needs heat treating soon and the edge is about 45-50thou... probably could take it down a bit? I thought I would leave a bit more meat, as its going to be heated in a charcoal bed, so I don't want to risk over heating it.
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I think you're right about leaving some meat on that. That is an uncontrolled uneven heat and a fast oil quench. If the thing is overall fairly thin, you will likely have some warping. If it is a simple bend it can be corrected by pulling the blade out of the oil after about five seconds and straightening it before it gets hard. If you get the ripples and waves in the edge, well, I haven't figured out how to fix that without grinding it out.

D2 is an air quench and you can go a lot thinner with air quench steels.
 
Thanks for all the info guys. It's really great having a place like BF to bounce questions around. :D
 
Air hardening steels can be taken darn near finish. Oil or brine quench steels will have crap that needs to be ground away. Leave appropriate meat for that grinding.

Rob!
 
Rob! said:
Air hardening steels can be taken darn near finish. Oil or brine quench steels will have crap that needs to be ground away. Leave appropriate meat for that grinding.

Rob!
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Thanks for the info Rob. I'm just beginning this journey and will take all the help I can get. By the way, I checked out your site... very nice work.:)
 
I use W1 and 1084 mostly, some O1. I grind the edges of my straight razors to .020" or less and have never had a blade crack. If I get the hollow grind a little uneven, sometimes there will be some minor wrinkling at the edge. I see this as a problem with the grind, though, not the overall thickness. I think I've even gone down to .010" once or twice without a problem.

Cracks and warps can be minimized by careful grinding, doing the normalizing cycles prior to hardening, heating the steel evenly, and avoiding overheating.

Josh
 
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