Toughness of H1?

[LJK]

I was looking at the steel chart in the great 2006 catalog and noticed the composition of H1 has almost no carbon, low to medium amount of chromium, large percentage of nickel and molybdenum. I would think with Spyderco's great heat treat this steel would be super tough! I've read here the edge holding is about on par with Aus-6, but what about toughness?

[Plowboy]

LJK,
Good question. I'm going to buy the Tasman in the next week or so...If I can still find them in stock. NGKs is out.

[CopilotATS-55]

"the more you grind the stuff the harder it is"
:D Eric Glesser i condensed the stuff he said at NYCKS

[zenheretic]

Hey LJK,

If toughness is equivalent to the hardness scale, the PE H1 is about 65 and SE H1 is 69 IIRC.

[STR]

It seems to be a relatively tough steel, with less wear resistance than some others which may account for why it is so easy to sharpen. It seems to hold its own for anything I use a knife for. If toughness is considered in the way it sheds the hazards of the elements like a ducks feathers do water then it is for sure one of the tougher steels there is. On the ocean waters and salt lakes and the wilds of the outdoors it rules supreme IMO for toughness.

STR

[Axlis]

It does scratch easily, but it's weather proof! :D

[Andre V]

There was a similar post a few weeks back about this.

http://spyderco.com/forums/showthread.php?t=19120&highlight=properties

IMO H1 is a great hardwearing steel, the edge holding properties are, IMO, as good as S30V.

H1 also gets harder with use.

Now i may cause some arguments over this, but my opnions are based on my experiences.

[greencobra]

First, I'm not a steel expert but do rotate my Salt I out with the Delica so only have experience to go on. Here's a work story. Doing the same chores as the VG-10, H-1 does them with no performance differences. From simple stuff, cutting fruit, opening sacks, to cutting poly tubing, etc. Light to med. use. The H-1 needs to be touched up more often and I do this because if say, I open a letter, I feel the blade catch on the paper. Not scientific, but I know it's time for the 204. H-1 comes back faster than the VG-10.

I sometimes let a co-worker use my knives. He has a habit of wacking the spine to clean debris off before he gives it back (I know), usually on a metal deck railing. The Delica VG-10 shows no sign of this "cleaning wack" but the H-1 has tiny dimples where the guy does the wacking. Nothing to really get excited about, just an observation. And it is correct that H-1 picks up light marks and scratches in use, again, nothing to bother me. On mine they can only be seen when the light hits a certain way.

[LJK]

Thanks everyone for the information. I guess toughness is probably the hardest think to measure. It seems to me you have to break or at least damage a blade to really find out how tough it is. I bet Spyderco knows. ;)

[HoB]

Its really hard to gauge. Hardness and toughness are not equivalent, but a single steel undergoes usually a toughness peak in the achivable hardness range, usually at lower hardness. Though I would figure one would have to distinguish between impact toughness and yield strength. A2 for example is supposed to have its toughness peak around 60 Rc IIRC.

For H-1 it is even more difficult to say, since the blade is effectively differentially hardened due to the workhardening at the edge and since the hardening process is different than for all other bladesteels. Given its workhardening behavior, I would wager that the toughness is rather low for repeated flexing (since each flex is likely going to harden the blade). So eventually, I would imagine you get breakage like a wire coathanger after repeated flexing. For the same reason I would imagine that impact toughness for single impact is rather high (the energy can be absorbed by the lattice) but that is all pure conjecture.

In the end, I would guess that we will simply have to wait what experience will tell us, but sofar I haven't heard of any complaints about H-1's brittleness. I have experienced occasional very minor chipping of the edge, but as I said, very minor, and I have reduced the edge angle to about 12 deg. per side.