0-1 Problem

[scott wheeler]

I recently forged 2 Nakiri's out of 0-1 bar stock relatively thin (1/16) and was grinding the tang to fit the handle. I dropped the blade and saw that there was a crack. Looking at it closer there were all sorts of cracks. I checked the other blade by tapping it with a hammer on the tang and sure enough it cracked rather easily. I forged them just below 2000 F never let them get below 1500 F and then normalized twice.

Any suggestions what I did wrong?

 

[EdCaffreyMS]

Sounds as if you had residual air hardening happening. The thinner the stock, the more likely this sort of thing becomes. Personally, after forging I always theremal cycle, then anneal, before continuing with the process. I've noticed as of late that there seems to be a trend towards doing as you did......normalizing only (and not annealing) before grinding.....and many times it doesn't work out well. I don't know if this is an attempt to "shorcut" things.....but I've had a number of calls and emails requesting help with the exact issue you experienced. As with others, I would encourage adding an anneling step to your post forging/pre-grinding process.

 

[scott wheeler]

Thanks Ed, wasn't looking to "shortcut the process" just never had that happen before, being a "noob" it was my first time forging something that thin. After posting I went and did a little research I guess with the thinner stock it did air harden. I didn't believe I had to anneal again it after normalizing twice. I'm going back out to the shop tonight to anneal the other piece and see what happens. I'll let you know.