Question about hamon / differential temper

K

Knifemaker.ca

Dealer - Purveyor
Just thinkin'.....

The few knives that I have ever seen fail / break in actual use, failed at the tip for the most part. (Not talking about HT fail)

If the tip is the weak spot, how come virtually all differential HT blades include the tip as part of the "hard" (not so tough) area?
 
the differentially heat treated blades include an hardened edge which run up to the tip. If this "ribbon" of martensite is narrow then it is less likely to break at the tip.
Consider that a knife shouldn't be used as a prybar, if the user want so then make a blade without distal taper and he should be happy ;)
 
As well, most knives that fail at the tip were more than likely overheated by a maker who either did not have a good grasp of his heat treating regimen, or had improper control of his heat in his forging process.
This may also include large grain size from the over heating which equates to cross-sectional weakness.
The tip is the easiest place to over heat, as it has the slightest mass in the entire blade.
 
There are more than one thing that can cause the tip to be the weak spot. As Karl mentioned, it could be from overheating the tip during the heat treatment. It might not be tempered enough and is too brittle for it's thickness. It could also be the geometry of the blade, it's just the thinnest part. The tip needs to be tempered martensite for strength and hardness. If it were pearletic steel then the tip would tend to bend even though it might resist breaking. The best thing to do is not to abuse your knives. They're not pry bars and shouldn't be used as such.

Doug
 
Doug Lester said:
The best thing to do is not to abuse your knives. They're not pry bars and shouldn't be used as such.
Doug
Click to expand...

Ya' think? Yer sure asking a lot. :les:
You know, some of those folks out there that promote "high performance" knives and on and on sure haven't done themselves or the industry any good.
I couldn't agree more - a knife is a cutting instrument.
You wanna chop down a tree - get an axe.
 
You must log in or register to reply here.
Back
Top