Knife snapped while straightening! (pics)

FWIW I can see where you'd be tempted to try this on a kitchen knife, but I'd never try to straighten someone else's knife. A machete sure, as I know the heat treat should accommodate this sort of treatment. On harder knives its easier to just work with the warp - grind it as one would a recurve and they get what they get.
 
straightening kitchen knives is part of my routine maintenance. and not henckels, talking about 300usd customs and very high end japanese knives, the knives i use professionally. i do it all the time, san mai or not, more often on chisel ground japanese knives as they are very prone to bending due to the construction, for those its clearly a normal step of sharpening as you cant hone the flat backside properly if the knife i bent even slightly ...

never broken on, never heard of someone breaking one in the decade i've spent reading KF/in the kitchen, foodie forum etc. daily. and its not the same kind of steel that henckel use, more.

i understand that straightening a knife that took a warp from heat treat should be done with great care, but a knife that was straight and got bent from use should not be a problem.

also those bends are very minute, you wont give 10° bend to a blade by using it in the kitchen, obviously. don't know how bad the knife was but if we are talking about the same thing i dont see what's the big deal.
 
Try filing it with a file, it is probably very hard to be broken in two places. The blade broke when you straightened it, I wonder how much bending it took to be able to set a bend previously.

The blades that I have broken had greyish and very fine powdery look. It looked many times smaller than what you have there. Very much like iron dust.

What does a fine and coarse grain tell?
 
Based on the (two) breaks, I suspect a fairly hard blade.

Based on the grain structure, I suspect a less then optimal Heat Treatment.


I imagine the knife took and held a good edge.

Isn't that what we all seek from knifemakers?


Breaking the knife as part of straightening during sharpening service,

...I would say the fault falls to the sharpener.


Just because higher quality cutlery might take this kind of stress,

...don't think all cutlery is up to these type of stresses.


Especially high production knives like Henckels.



Big Mike
 
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