Call for Charpy toughness samples

Here is the summary of the toughness numbers in comparison with the other grades that have been tested. I will be doing a more deep dive into the effect of heat treatment variables, etc. hopefully soon.
toughness-summary.jpg
 
I think z-wear looks pretty good at high hardness. The heat treatments were designed to compare cryo vs no cryo and 400F vs 1000F tempers. If the heat treatments were designed for lower hardness its 58-60 Rc toughness number would probably be better. It has much higher wear resistance than AEB-L so it would be expected to have somewhat lower toughness.

The cru-wear is indeed the ingot version.

M390 is a very high carbide volume steel (10V levels) and at 62 Rc it probably wouldn't be expected to be any better than it is.
 
So the different heat treatments on zwear didn’t seem to change the toughness dramatically!! Looks like maybe a couple lb ft difference! That’s interesting! But that’s only testing one aspect!
 
I’ve just read how zwear is closer to 3v in toughness! Im guessing 3v at 60 rc will test much better than any of these! Im also looking forward to see how vanadis 4e and 8670 test!
 
I'm definitely excited to continue to add more steels and more heat treatments so that we can have a relatively thorough database of steels across manufacturers. There are very few toughness comparisons between Crucible and Bohler-Uddeholm steels, for example. The more people we have like Warren who are willing to generate the samples the faster we can get more data.
 
Aebl is the beast to beat! Can’t wait for those monster tough steels, like 8670.

So Zwear doesn’t reveal much difference in toughness between 1000F and cryo+400F temper! I wonder if this is the case with Vanadis 4 extra, also. So this could explain why two of my favorite makers (Fredrik Haakonsen and Adam Kornalski) insist in using high tempers when heat treating Vanadis 4 extra, and for toughness they just play with hardness.
 
hugofeynman said:
Aebl is the beast to beat! Can’t wait for those monster tough steels, like 8670.

So Zwear doesn’t reveal much difference in toughness between 1000F and cryo+400F temper! I wonder if this is the case with Vanadis 4 extra, also. So this could explain why two of my favorite makers (Fredrik Haakonsen and Adam Kornalski) insist in using high tempers when heat treating Vanadis 4 extra, and for toughness they just play with hardness.
Click to expand...
See slide 34: http://thecbm.co.uk/wp-content/uplo...16-Uddeholm-Tool-steel-selection-for-AHSS.pdf
 
rodriguez7 said:
I’m having a hard time understanding that graph. I’m guessing it’s showing tempering temps, and it’s showing optimal is 1020 f, for 2 hours followed by a second lower temper! Which yields decent impact toughness!
Click to expand...
Ha! You need to switch to Celsius.
 
rodriguez7 said:
So the different heat treatments on zwear didn’t seem to change the toughness dramatically!! Looks like maybe a couple lb ft difference! That’s interesting! But that’s only testing one aspect!
Click to expand...

The no cryo/high temper was below 20, even though it was a bit softer. The cryo/low temper examples were all over 20. There was a noticeable difference, but it isn’t like switching steels. I’ll let Larrin comment on the significance of 4-5 lb ft in our applications. You get better stainless properties this way too. I’ve always said the standard heat treat is great, but this is a bit better. Will the eta carbides make a difference in wear resistance? Different testing is required.

Now look at what D2 toughness is at Rc61, then cru-wear, then z-wear. That seems like pretty great improvements, regardless of which heat treat we use. I will tell you the wear resistance of z-wear at Rc62+ far eclipses 3v at Rc60.
 
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rodriguez7 said:
I’ve just read how zwear is closer to 3v in toughness! Im guessing 3v at 60 rc will test much better than any of these! Im also looking forward to see how vanadis 4e and 8670 test!
Click to expand...

Z-wear will be tougher than 3v if both steels are above Rc62/63. At Rc60, z-wear will not be as tough as 3v, both being at that hardness. The way I see it, is choose the steel based on intended use. I’ve done a few kitchen knives in z-wear cru/wear, and they perform exceptionally well. I’m going to send another cru-wear sample to make sure there wasn’t a mix up in the steels. My first hand experience is that there isn’t that much difference in real work use. I run cru-wear one Rc point lower than z-wear, and haven’t seen it nearly as chippy as 20cv. This testing shows it about the same as 20cv.

That makes me question whether the z-wear high temper, and cru-wear low temper samples were mixed up. I’ll send another high temper sample too, just to make sure.
 
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