Edge Retention/Rolling Test Stand

[Jan]

Thanks Jan and Mark. I get it now Jan. Yes, I'm a little concerned but hopeful of the sharpness levels coming back. What makes me hopeful is that Brad seems to place a fair amount of faith in the predicted outcome due to the fact that this is a air-hardened steel. We sharpened one of these Saturday and got it down to 275 without a whole lot of effort. We'll try to do better. 275 doesn't give us a whole lot of fudge factor. I don't mind if we send them in at 225 and they come back 300. We have data on 300 edges so can still make good comparisons. As a fall-back, and assuming the edges come back higher (duller), we're hopeful that stropping on leather might improve it (surface crap-ola). If the edge swells during heat treat though, that is unlikely to help us significantly. This experiment is a big deal to us though because it represents the very clear opportunity to see if sharpening, in and of itself, somehow significantly affects the yield strength characteristics of the steel. If it doesn't, we move on. If it does we then can investigate if this is true of all sharpening methods or just some and to what degree.

OK Mike, I am really eager to know the impact of quenching on the edge sharpness.  I have not gathered enough own results yet.

Mr. Mark you are correct, the volume of martensite is larger, but this impact on the edge thickness will be small.  
What I am wondering about is not only the edge thickness increase caused by formation of different surface layers, but also the misalignment of grains in the edge vicinity.


Introductory reading about quenching and martensite formation is of course the book by prof. Verhoeven. As complementary (apparently more popular) reading I have found a paper by prof. Helmut Foell from Uni in Kiel, Germany.

Jan