Brittle Edge

[SteveS]

Just finished up an S30V kitchen blade - thin edged, hollow ground. Doesn't hold an edge real well.

The brass rod test kinda created a wire edge. But, no major chipping or anything, but the edge just doesn't hold up, like S30V should.

It's about 61HRC. Maybe that's too hard? I'm thinking it not just a hardness issue.

I'm thinking maybe I have to change the angle, but it's just under 20 degrees. That's not very steep.

It's weird. I'm feeling lost here.

Steve

[RJ Martin]

Steve: What was the HT cycle you used?

[AwP]

Did you strop or buff off the burr before doing the brass rod test? If there's a burr that's aligned with the edge (like butchers like em) then it'll fold up on the brass rod test not giving accurate results on the "real" edge under the burr.

[SteveS]

I'm not at home with my book, but by memory

1200 for 2 hrs, oven cool for stress relief
1950 for 20 minutes
Plate quench
8 HRS cryo
2 hrs 400
2 hr 400

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You know, RJ, it might be the angle. I usually use 15 degrees, but this is going to a family with little kids, and plenty of abuse. So, I went 20 degrees. Maybe I'm not used to this edge.

I did some apple slicing. Then cut up some aluminum cans. The edge is still the same. No chipping or rolling. It just doesn't shave (well just a bit). It's not a great slicer, but it's not getting worse.

Maybe I'm not used to this cutting angle.
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AWP - Thanks!

I used a leather belt, but that might not have removed the burr like I thought. It's gone now.

Steve

[RJ Martin]

Steve: 400 is kind of low for S30V. I use 550 or 600, depending on the knife. My guess is the edge quality would improve if it were a bit softer.

[SteveS]

OK Boss, I'll do that on some blades from the same batch.


Thanks,

Steve