H1 Steel - How it Works

Larrin said:
Any metal work hardens, it doesn't need special alloying.

My biggest concern for using austenitic steel would be making sure the final retained austenite content isn't too high. Austenite greatly reduces the "yield strength" relative to the hardness.
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Oh I know all metal work hardens. But my understanding is that it doesn't increase abrasive wear, just the resistance to plastic deformation. So it does increase the edge stability of the relatively soft steel used in that context, which is important for the thin geometry used on scythe blades, but the transformation of austenite to martensite from plastic deformation seems as though it would have the potential for increasing the abrasive wear resistance in addition, and so improve edge retention. The question is whether or not it'd be able to be done in such a way that it produced any noticeable benefit over conventional work-hardened 1080 that had been heat treated to 45 RC before the cold work was performed. I'm not sure if it's possible to produce an austenitic steel blade that could be similarly treated and have it turn out any better than the conventional method. It's just that, if all else was somehow held equal, an increase in martensite at the edge would get it closer to the kind of edge retention that American/English/Nordic blades do, simply being heat treated at ~55+. Does that make sense? I'm unsure of the parameters that would need to be balanced to produce the effect. It just strikes me as an interesting possible application since it's one of the few tool formats literally intended to be beveled by hammering it to produce the kind of plastic deformation needed to cause the conversion.

The European style of blades are able to be made incredibly light thanks to the rigidity coming from cold tensioning rather than thickness or additional folds beyond an upturned lip at the spine. A major reason for them not being heat treated harder is that the tensioning, done cold, is more likely to cause cracking, and so the failure rate during manufacturing goes way up. It also makes the edge more resistant to peening, so having an edge that would essentially become wear-resistant martensite through peening would be of potential advantage.
 
Like I said, my concern with hammering an austenite edge would be excessive retained austenite after the work hardening process. The cold rolled H1 uses a controlled process to transform the austenite, and even that probably has significant retained austenite. Retained austenite can reduce yield strength even with equivalent hardness.
 
Larrin said:
Like I said, my concern with hammering an austenite edge would be excessive retained austenite after the work hardening process. The cold rolled H1 uses a controlled process to transform the austenite, and even that probably has significant retained austenite. Retained austenite can reduce yield strength even with equivalent hardness.
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So the reduction in yield strength due to RA would be a consideration depending on application?
I would imagine that in a sythe application yield strength would be a concern because of the potential of bad swings hitting dirt or rocks in usage.
 
danbot said:
So the reduction in yield strength due to RA would be a consideration depending on application?
I would imagine that in a sythe application yield strength would be a concern because of the potential of bad swings hitting dirt or rocks in usage.
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Yield strength is usually the more important measure of strength in a knife edge because that’s the point at which the steel begins to permanently deform.
 
Used properly they're pretty low-impact tools. The motion is more like sweeping a broom than swinging a golf club. But they're only 7-9° per side and run close to the ground so they do occasionally find something they weren't meant to, and thick-stemmed weeds do have the potential to wrench on a blade if you make a bad cut.
 
Larrin said:
Yield strength is usually the more important measure of strength in a knife edge because that’s the point at which the steel begins to permanently deform.
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So the edge would tend to roll instead of chip even with the increased martensite?
 
FortyTwoBlades said:
I'm now curious if the austenite-to-martensite cold working transformation could be capitalized on with European-style tensioned/peened scythe blades. They're typically made out of a steel like 1080 and tempered down to ~45RC with the body of the blade drawn out in hot forging to about 1-1.5mm thickness then tensioned by cold peening the span of the blade, giving the blade its required rigidity. The blades are then beveled through cold peening, drawing out a thin edge that's then honed with a stone. By comparison, American, English, and Nordic blades are typically heat treated around 55+ RC in similar steel and beveled by grinding, with the body having been given one or more corrugations for rigidity, and the span of the blade usually being a bit thicker than Euro blades. The difference in edge-holding ability between the two camps is huge in my experience, and it makes me wonder if the Euro type could compensate for its otherwise soft heat treatment by exploiting that sort of transformation?
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Are the Euro ones worse at edge-holding than the heavier ones that are harder?
 
Mecha said:
Are the Euro ones worse at edge-holding than the heavier ones that are harder?
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The harder American/English/Nordic type holds an edge about 5x as long in my experience. I insist on a VERY keen edge on my blades and on typical Euro blades I take 3-5 strokes and it's already duller than I consider acceptable. In the rare cases where I use a Euro type blade it's usually a Russian one because they take something of a middle ground and make their blades shaped generally like the typical Euro sort, but just a touch thicker, a decent amount harder (but not so hard as American/etc. blades) but also with less tensioning, which does have the drawback of making them a bit floppy in longer lengths. If they used a V-shaped rib along the back like American blades it'd stiffen 'em right up, and I'm actually working with that company (Arti) to try to get American pattern blades produced to my specs.
 
I am most appreciative of you input , Larrin ! :)

But I was kinda hoping for some scientific basis for the anecdotal superiority of Sypderco H1 serrated over PE !? :confused:
 
Would certainly be interesting to see independent hardness testing at various points on the blades. It's a bit of a mystery.
 
Larrin said:
An article about the highly corrosion resistant H1 steel. It's very different than most other knife steels for several reasons, including that the steel is not heat treated by the knife manufacturer. In fact, the steel isn't quenched and tempered like typical knife steel. Learn about how it works instead here: https://knifesteelnerds.com/2019/06/24/h1-steel-how-it-works/
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Thank you for posting...I really enjoyed the article!
 
DocJD said:
I am most appreciative of you input , Larrin ! :)

But I was kinda hoping for some scientific basis for the anecdotal superiority of Sypderco H1 serrated over PE !? :confused:
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The only CATRA testing I have seen of serrated edges was for ATS-34. That knife barely dulled at all over a full 200 cuts of that nasty cardstock in the CATRA test. I don't know how H1 would improve on that. https://knifesteelnerds.com/2018/11/26/steel-edge-retention2/
 
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