Rex45=Hap40?

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Larrin
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Re: Rex45=Hap40?

Postby Larrin » Thu Aug 27, 2020 10:13 am

Albatross wrote:
Thu Aug 27, 2020 8:19 am

That's interesting. Is there an industry standard maximum allowance for sulfur content?
Not really. Not unless there is a European spec I don’t know about. There may be specific industries like aerospace with more rigorous restrictions but for knife steel they are just making the steel with their normal practices to try to minimize sulfur and they probably don’t throw away anything unless it is abnormally high.

When I compared composition measurements from Crucible, Carpenter, Uddeholm, and Bohler the sulfur levels were pretty similar. https://knifesteelnerds.com/2020/03/30/ ... echnology/

There are certain steels occasionally made to be “free machining” with intentional sulfur additions but those aren’t typically used for knives.
http://www.KnifeSteelNerds.com - Steel Metallurgy topics related to knives

wrdwrght
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Re: Rex45=Hap40?

Postby wrdwrght » Thu Aug 27, 2020 10:16 am

Chemically the same does not mean the same user-experience. Remember heat-treat and blade geometry are also factors, and other things being equal, are more significant.

So has said our own Larrin.
Last edited by wrdwrght on Thu Aug 27, 2020 10:18 am, edited 1 time in total.

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Takuan
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Re: Rex45=Hap40?

Postby Takuan » Thu Aug 27, 2020 10:16 am

Larrin wrote:
Thu Aug 27, 2020 10:08 am
Yes they are the same steel, a very common PM high speed steel in Europe especially. The European designation is 1.3244. It’s sold under a lot of trade names like ASP2030, S590, and Vanadis 30.
Thanks, Larrin. I continue to learn a lot from your expertise (both here and on the Knife Steel Nerds website).
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Takuan
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Re: Rex45=Hap40?

Postby Takuan » Thu Aug 27, 2020 10:22 am

Albatross wrote:
Thu Aug 27, 2020 8:19 am
Larrin wrote:
Thu Aug 27, 2020 8:09 am
Takuan wrote:
Wed Aug 26, 2020 8:29 pm
According to Spyderco’s steel comparison chart ( https://www.spyderco.com/edge-u-cation/steel-chart/), they do seem to have very similar chemistry in terms of carbon, chromium, cobalt, molybdenum, tungsten, and vanadium. REX45 seems to have manganese, silicon, and sulfur, which are not included in HAP 40.
Mn and Si is in every knife steel so if they aren't listed it's just because the amounts aren't shown in the datasheet. Sulfur is usually not an intentional addition but an impurity, so some datasheets will list a maximum allowable amount.
That's interesting. Is there an industry standard maximum allowance for sulfur content?
This reminds be a bit of the FDA policies that allow certain "tolerable" amounts of rodent hair and insect parts in our food. :)
"We cannot live better than in seeking to become better."
--Socrates

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Albatross
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Re: Rex45=Hap40?

Postby Albatross » Thu Aug 27, 2020 10:29 am

Takuan wrote:
Thu Aug 27, 2020 10:22 am
Albatross wrote:
Thu Aug 27, 2020 8:19 am
Larrin wrote:
Thu Aug 27, 2020 8:09 am
Takuan wrote:
Wed Aug 26, 2020 8:29 pm
According to Spyderco’s steel comparison chart ( https://www.spyderco.com/edge-u-cation/steel-chart/), they do seem to have very similar chemistry in terms of carbon, chromium, cobalt, molybdenum, tungsten, and vanadium. REX45 seems to have manganese, silicon, and sulfur, which are not included in HAP 40.
Mn and Si is in every knife steel so if they aren't listed it's just because the amounts aren't shown in the datasheet. Sulfur is usually not an intentional addition but an impurity, so some datasheets will list a maximum allowable amount.
That's interesting. Is there an industry standard maximum allowance for sulfur content?
This reminds be a bit of the FDA policies that allow certain "tolerable" amounts of rodent hair and insect parts in our food. :)
As I typed the question, I was thinking about the time I heard that peanut butter contained a certain, "tolerable" amount of undesirables. I would like to meet the person who deemed this "tolerable", because I would describe it a bit differently... :mad: :confused:
sal wrote:
Fri Nov 09, 2018 3:01 pm

...But in general, I'm all about high performance, Ergos, safety. That's why I've been accused of "deigning in the dark"...

sal

Karl_H
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Re: Rex45=Hap40?

Postby Karl_H » Thu Aug 27, 2020 11:30 am

I wouldn't worry too much about the maximum allowable contaminants (S, P, etc.) in the material specs for knife steels, particularly HIP PM steels. The PM process essentially prevents large non-metallic agglomerations from forming and inter-granular corrosion is not a major concern for knife use.

I doubt the casual knife user would notice much difference in the edge stability between Spyderco's HAP40 and REX45. I appreciate the stainless steel cladding on HAP40. All else being equal, I prefer for HAP40 for the stainless steel cladding.

I believe only the Seki models have been offered in HAP40. Only Golden models have been offered in REX45.

I hope that we will eventually see mass production of SS clad tool steels for cutlery in the United States. I also hope that SS clad HAP40 is eventually offered for Taichung models, such as the Ikuchi.

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SubMicron
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Re: Rex45=Hap40?

Postby SubMicron » Thu Aug 27, 2020 12:35 pm

As others mentioned, compositinally the two are very similar, almost the same. As delivered by Spyderco, the difference between the two seems to be the hardness and the fact that their HAP40 has a stainless SUS410 outer jacket. Neither HAP40 or REX-45 are stainless.

Whether the assumed lower hardness in HAP40 is a byproduct of the SUS410 cladding, or if its intentional and by design, I'm very happy with it's performance as delivered. My HAP40 Dragonfly appears to have higher fine edge stability than my ZDP-189 Dragonfly.

HAP40 doesn't have to be run at balls-to-the-wall high hardness for it to be amazing.

I use HAP-40 and REX-45 at work in the Dragonfly and Lil Native. I bring each with me everyday. I'm impresed with both.

With the higher hardness of REX-45 comes better edge stability which gives the benefits of a more durable edge that can provide better overall edge retention.


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