Deadboxhero wrote: ↑Sun Sep 16, 2018 11:48 am
Mordhaus wrote: ↑Sat Sep 15, 2018 11:58 pm
Deadboxhero wrote: ↑Sat Sep 15, 2018 9:02 pm
Slapped some 52100 at 60 hrc on a 36 grit belt to compare to 4v at 67hrc. I dipped them both in tap water and watched the fun.
Looks like I'm wrong, the 4v is not as reactive as 52100
In 5 min the 52100 start reacting.
The 4v had less reaction.
Still, I'd be more watchful with 4v then other tool steels.
It's alot more reactive then M4, 3V, Cruwear, PD-1 and Z-Wear, CPM D2 and Psf27
Am I missing something? It has 5% chromium, which is more than M4/Rex45/Hap40 (which range from 4%-4.75% cr). It should theoretically be more resistant than those. D2 is just shy of stainless level, so that is obviously much higher resistance. Cruwear/3V/PD-1/Z-Wear come in around 7.5%-7.75% cr so they should be slightly more resistant.
Unless there is a chemical reaction to some other material in the steel that I am unaware of, this should be easily comparable to any of the common semi stainless steels except for D2 and PSF27. Basically in the middle, leaning towards the M4 family.
Larrin shows in a list here from the article.
Basically Steels at the top of the list are more stainless/less reactive then steels at the bottom. However, he has them organized by there free Chromium in solution not tied up in carbides after heat treatment, so near the bottom middle there may be some caveats.
In the chart, he shows:
Austenizing temp, Chromium, molybdenum and PREN
The Austenizing temp is important because it is afactor in how much alloy is in solution.
Using the chromium percentage, Larrin shows how much Chromium is in solution to create an oxide film to passivate reactivity.
The Molybdenum is not just purely for Carbide formation and hardenbility. It also helps with pitting, he shows how much molybdenum is in solution.
The PREN stands for Pitting Resistance Equivalent Number. You'll notice that Vanadis 4 (4V is a copy) has more Cr in solution then M4 but less PREN due to the lower amount of Molybdenum in solution.
The article is really great and covers alot of details.
It's so awesome that we have a legit Metallurgist in the knife community sharing.
Subscribe to the website great great information there and more coming.
The next article is about Nitrogen steels and how Nitrogen works in the steel.
So exciting!
I read the article. Since I am not a metallurgist, I took away the most information from the following line: "The ranking by Cr content in solution is probably more accurate for predicting the relative corrosion resistance of each."
So if we don't have the other information (temps etc) we can guesstimate that, at worst, 4V is comparable to the M4 family. Not significantly worse as was said earlier. PREN only seems to count for pitting and crevice corrosion when exposed to Chloride, IE Saltwater (
https://en.wikipedia.org/wiki/Pitting_r ... ent_number). I wouldn't dare expose tool steel to saltwater unless I had to, even then I would take all steps to make sure the blade was cleaned and oiled after exposure (definitely oiled before).
Now I know you have done work with 4V on your custom knives so you have field experience, but I also think you have been pushing your 4V to the max RC. The article inferred that the higher RC is going to be less resistant to corrosion because apparently the higher you go in RC the less Cr is available in solution. It may be that the custom blades you have are not going to exhibit the same response as those of the one on this upcoming para3.
Obviously I am just making estimates based off numbers. I don't have your experience with the 'real steel' yet. I might be completely wrong, but I would think that it should definitely be somewhat resistant to average exposure to non-saltwater and humidity, at least to m4 levels as I said, albeit m4 should technically be more resistant to saltwater depending on treatment.