Hand Tools

Re: we're not necessarily bending *LINK* *PIC*

Steve D, CT
For chisels, an edge fracture from a prying cut is more from the ultimate strength than toughness. Hammering into a knot would be a toughness thing, as you have already stated.

For planes there shouldn't be any way to make a prying cut so knots and foreign matter would make the impact to chip.

I was poking around the web this afternoon and found a graph relating to 4340 showing a toughness curve based on tempering temp along with the hardness values. It's not a cutting steel, I know, but it relates to optimization.

Here is the page with the info since I couldn't post 2 images from the web.

The tradeoff for this material is between 5 times the toughness against losing half your UTS.

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