DISCLAIMER: DO NOT REPEAT THIS! A customer of mine, going by the handle @pm2og on Instagram, decided to put one of my Rex121 blades at 71 HRC to the test. This is what proper heat treat can do folks.
I found the performance above 71 HRC not to be satisfactory in knives. Seeing most REX121 at 70 HRC, I'd call 71 anything but conservative to be honest. I do use a 73.6 HRC REX121 tool I made for scribing lock faces though - it is so brittle that it broke in two pieces when I tossed it to the floor. 72 HRC also didn't satisfy me long term.
Everyone got different standards. I did make a few Rex121 samples in that hardness range only to realize that in this very high hardness range, we should indeed stick to HV or HRA like literature says since the HRC scale officially stops at 70 HRC. Beyond 72 HRC, crazy measuring results can happen - I did get 75 HRC measurements for example on Rex121 a few times on many blades when going for max hardness; and always disregarded them as errors/outliers. It also really depends on tve batch of Rex121; at that crazy alloying content, you can get up to 0.8 HRC extra if somewhat more carbon is in the steel. The hardest blade from Rex I ever made on any batch I bought which performed well (meaning it wasn't as brittle as glass and could be dropped) I measured 1210 Vickers (1kgf) which I could convert HRC for marketing reasons, but it wouldn't be state of the art to do that. The hardest I ever made was 1270 HV. Long story short: I take all my HRC measurements past 72 HRC with a grain of salt and stick to my Vickers tester.
Das ist schon impossant, allerdings wäre es aufschlüssiger, zu sehen, wie oft man das machen kann, bis das Messer aufgrund der angesammelten Gitterdefekte durchbricht bzw. Ausbrüche bekommt. Selbst mit einem Gummihammer dürfte das ja an der Schneide irgendwann so laufen.
Vielleicht macht er mal weiter - was mir hier wichtig war zu zeigen ist, dass 71 HRC eben NICHT wie Glas beim ersten Schlag zerbricht, obwohl die Klinge deutlich härter als Glas ist. Der bisherige/aktuelle Konsens ist ja leider immer noch mehrheitlich, dass alles über 60 HRC schon kritisch wird, was die Zähigkeit angehet. Wobei ich argumentieren würde, dass die Druckstabilität mindestens so wichtig ist, was mit diesem Test eigentlich mehr getestet wird als die sog. "Kerbschlagzähigkeit". (Auch ein schönes deutsches Wort.) Wenn ich mal etwas Zeit und entsprechende Ressourcen habe, würde ich gerne eine Fixtur bauen, weleche diesen Test mit verschiedenen Testmedien reflektiert, aber in einer absolut kontrollierten Umgebung. Würde gerne noch viel mehr schreiben, aber muss in die Werkstatt zurück; die Messer machen sich nicht von alleine. 😅
thats a gimmick. reminds me of BBB plucking hardwood and making dramatic cracking sounds. These are not real tests of toughness, they are parlor tricks. Go ahead and gently tap that edge on the lip of a glass or a steel mug and see what happens. Forget the dramatic hammer. Gently tap the edge onto the corner of that brick and see what happens. Strength and toughness are not the same thing. Harder steel is stronger. Harder steel is also less tough.
You seem to have missed the purpose of this test. The purpose was demonstrating to people my Rex121 at 71 HRC knives can be used without treating them like glass, which is what most people would instinctively assume. No tricks here. If you look around and check out what I do, you'll arrive at the same conclusion I hope. Also, how should a gentle tap on glass be a better test for either toughness or strength, that makes no sense. (Less amount shock won't give us any additional insights.) Side note, since you mentioned strength vs hardness correlation: this test is indeed a demonstration of strenght first and foremost, which when it comes to knives arguably is at least as important, if not slightly more important often than gross toughness. But due to the impacts generated by the blows of the hammer, toughness also is being tested here. Long story short, for the afformentioned reasons, this a good, reality based test for what advanced steels combined with thought out heat treats can achieve.
@@kknives_switzerlandI think what he means is that the contact area is too large with full edge length, combined with a small rubber faced hammer, there is really not much impact, where as in real life, it is usually only a tiny protion contacting glass or ceramic. I understand that this test is not to boast its toughness rather than being a basic check as “It is not like glass brittle”. However, I think it is worth trying the tapping test, let’s see what happens.
DISCLAIMER: DO NOT REPEAT THIS!
A customer of mine, going by the handle @pm2og on Instagram, decided to put one of my Rex121 blades at 71 HRC to the test.
This is what proper heat treat can do folks.
Yikes
I didn't expect this to be honest. Well done.
Bet you were clenching the cheeks together watching this one😆 I know I was!
You bet I was. But I also was confident in my product.
@@kknives_switzerland as you should be!💪
Stark, also das die Schockbelastung so gut aufgefangen wurde. 🙂
Kinda important to know what heat treatment protocol was used .. but not so surprising the hardness is conservative for that steel.
I found the performance above 71 HRC not to be satisfactory in knives. Seeing most REX121 at 70 HRC, I'd call 71 anything but conservative to be honest. I do use a 73.6 HRC REX121 tool I made for scribing lock faces though - it is so brittle that it broke in two pieces when I tossed it to the floor. 72 HRC also didn't satisfy me long term.
@ I remember BigBrownBear showing off 74 hrc+ on a knife he claimed his custom heat treatment would make it durable idk how much of that is true.
Everyone got different standards. I did make a few Rex121 samples in that hardness range only to realize that in this very high hardness range, we should indeed stick to HV or HRA like literature says since the HRC scale officially stops at 70 HRC. Beyond 72 HRC, crazy measuring results can happen - I did get 75 HRC measurements for example on Rex121 a few times on many blades when going for max hardness; and always disregarded them as errors/outliers. It also really depends on tve batch of Rex121; at that crazy alloying content, you can get up to 0.8 HRC extra if somewhat more carbon is in the steel. The hardest blade from Rex I ever made on any batch I bought which performed well (meaning it wasn't as brittle as glass and could be dropped) I measured 1210 Vickers (1kgf) which I could convert HRC for marketing reasons, but it wouldn't be state of the art to do that. The hardest I ever made was 1270 HV. Long story short: I take all my HRC measurements past 72 HRC with a grain of salt and stick to my Vickers tester.
Das ist schon impossant, allerdings wäre es aufschlüssiger, zu sehen, wie oft man das machen kann, bis das Messer aufgrund der angesammelten Gitterdefekte durchbricht bzw. Ausbrüche bekommt. Selbst mit einem Gummihammer dürfte das ja an der Schneide irgendwann so laufen.
Vielleicht macht er mal weiter - was mir hier wichtig war zu zeigen ist, dass 71 HRC eben NICHT wie Glas beim ersten Schlag zerbricht, obwohl die Klinge deutlich härter als Glas ist. Der bisherige/aktuelle Konsens ist ja leider immer noch mehrheitlich, dass alles über 60 HRC schon kritisch wird, was die Zähigkeit angehet. Wobei ich argumentieren würde, dass die Druckstabilität mindestens so wichtig ist, was mit diesem Test eigentlich mehr getestet wird als die sog. "Kerbschlagzähigkeit". (Auch ein schönes deutsches Wort.)
Wenn ich mal etwas Zeit und entsprechende Ressourcen habe, würde ich gerne eine Fixtur bauen, weleche diesen Test mit verschiedenen Testmedien reflektiert, aber in einer absolut kontrollierten Umgebung. Würde gerne noch viel mehr schreiben, aber muss in die Werkstatt zurück; die Messer machen sich nicht von alleine. 😅
Not as tough as S7 for masonry, but this Rex 121 handled it alright.
S7 and Z-Tuff definitely are the ticket for toughness. My fav steels for any impact focused blade.
👏👏
Thanks for watching
👍
Rex 121 auf 71hrc und so zäh das ist unglaublich. Das Messer sollte eigentlich komplett zerspringen
Ich bin sehr zufrieden mit dem Resultat
thats a gimmick. reminds me of BBB plucking hardwood and making dramatic cracking sounds. These are not real tests of toughness, they are parlor tricks. Go ahead and gently tap that edge on the lip of a glass or a steel mug and see what happens. Forget the dramatic hammer. Gently tap the edge onto the corner of that brick and see what happens. Strength and toughness are not the same thing. Harder steel is stronger. Harder steel is also less tough.
You seem to have missed the purpose of this test. The purpose was demonstrating to people my Rex121 at 71 HRC knives can be used without treating them like glass, which is what most people would instinctively assume.
No tricks here. If you look around and check out what I do, you'll arrive at the same conclusion I hope.
Also, how should a gentle tap on glass be a better test for either toughness or strength, that makes no sense. (Less amount shock won't give us any additional insights.)
Side note, since you mentioned strength vs hardness correlation: this test is indeed a demonstration of strenght first and foremost, which when it comes to knives arguably is at least as important, if not slightly more important often than gross toughness. But due to the impacts generated by the blows of the hammer, toughness also is being tested here. Long story short, for the afformentioned reasons, this a good, reality based test for what advanced steels combined with thought out heat treats can achieve.
@@kknives_switzerlandI think what he means is that the contact area is too large with full edge length, combined with a small rubber faced hammer, there is really not much impact, where as in real life, it is usually only a tiny protion contacting glass or ceramic.
I understand that this test is not to boast its toughness rather than being a basic check as “It is not like glass brittle”.
However, I think it is worth trying the tapping test, let’s see what happens.