What have I done?

O

Oldman57

Joined
Aug 19, 2017
Messages
11
Recently I made a small veg. chopper from an old circular saw blade. I had my forge running for another project and decided to heat treat the chopper blade too. I got it to non magnetic and then quenched it in hot water. ( just to see what would happen) . The blade got a slight warp, so I straightened it with a couple taps with hammer on my anvil.
The file hardness test showed great, so proceeded to sand and polish. When I got to about 600 grit a pattern of circular microscopic “cracks” started showing up, radiating out from where I tapped it to take the warp out. Is this the martensite cracking, or what? Looks kinda cool but is the blade shot now?
 
Pilsner said:
You’ll get the best advice in the knife makers’ forum. Maybe take a photo?
Click to expand...
Pics didn’t turn out very well. The pattern looks just like what a hard boiled egg looks like when tapped on the counter to break the shell.
 
My understanding is that your procedure for heat threating the steel that saw blades are made off... is not appropiate at all. I would say the blade is shot.

So far I have made only one knife from saw blade steel (reciprocating blades, straight and thick) and I didn't do any kind of heat threat. It cuts great and holds an edge great as well. No need to mess with it.

Let's see if the knifemakers have anything else to say about this.

Mikel
 
This isnt the bladesmith section and im no bladesmith but quenching in water is no good. Water will pull the heat out of the blade too fast casuing stress cracks.
 
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