Spyderco Forums

ikaretababy wrote: ↑

Sat Sep 15, 2018 5:35 pm

i wish every retailer would have a 1 per household policy for sprints

At least for the first few days or a week...after that, take the limiter off and let people have at em if there are any left.

Thanks @Sharp Guy.

I don't know much about 4V but from what I've read on this forum it's a great steel. Is it stainless? Is i comparable to any other "super steel" that is used for knife blades these days? Thanks in advance for any info.

Brown_Recluse wrote: ↑

Sat Sep 15, 2018 6:52 pm

I don't know much about 4V but from what I've read on this forum it's a great steel. Is it stainless? Is i comparable to any other "super steel" that is used for knife blades these days? Thanks in advance for any info.

It is not stainless.

Brown_Recluse wrote: ↑

Sat Sep 15, 2018 6:52 pm

I don't know much about 4V but from what I've read on this forum it's a great steel. Is it stainless? Is i comparable to any other "super steel" that is used for knife blades these days? Thanks in advance for any info.

It's in the category of M4, Cruwear, Rex45, it's claim to fame is it's a stronger and more wear resistant then 3V while still retaining some simliar toughness.

It's the most reactive out of the these types of steels though. 4v is about as stainless as 52100.

Deadboxhero wrote: ↑

Sat Sep 15, 2018 7:07 pm

Brown_Recluse wrote: ↑

Sat Sep 15, 2018 6:52 pm

I don't know much about 4V but from what I've read on this forum it's a great steel. Is it stainless? Is i comparable to any other "super steel" that is used for knife blades these days? Thanks in advance for any info.

It's in the category of M4, Cruwear, Rex45, it's claim to fame is it's a stronger and more wear resistant then 3V while still retaining some simliar toughness.

It's the most reactive out of the these types of steels though. 4v is about as stainless as 52100.

Thanks! That's what I needed to know.

Deadboxhero wrote: ↑

Sat Sep 15, 2018 7:07 pm

It's the most reactive out of the these types of steels though. 4v is about as stainless as 52100.

Really? I did not know that. I'm no metallurgist but I would have thought with the extra chromium, molybdenum, and vanadium, it would have been a lot better than that.

Deadboxhero wrote: ↑

Sat Sep 15, 2018 7:07 pm

It's the most reactive out of the these types of steels though. 4v is about as stainless as 52100.

I don't mean to stir up trouble, but CPM 4V is much more corrosion resistant than carbon steels in my experience. It's nowhere near any stainless steels and far behind CPM Cruwear, but it's also far ahead of simple carbon steels. 52100 has 1.3-1.6% chromium, so it's between 4V and simple carbon steels.

I made several 4V knives for my groomsmen, and none of them have had any notable corrosion in several years. The one of that batch that I kept also has had very little signs of reactivity. Based on my experience, and that it has 5% chromium, 3% molybdenum, and 3.85% vanadium, I'd put its corrosion resistance solidly in the CPM M4 and K390 range. I would never expect 52100 to be that corrosion resistant at only 1.45% chromium. It does depend on heat treatment, though, so that may explain mine having better corrosion resistance than someone else's.

Shawn,

Have you had corrosion issues with your samples of CPM 4V?

Thanks

The Meat man wrote: ↑

Sat Sep 15, 2018 7:20 pm

Deadboxhero wrote: ↑

Sat Sep 15, 2018 7:07 pm

It's the most reactive out of the these types of steels though. 4v is about as stainless as 52100.

Really? I did not know that. I'm no metallurgist but I would have thought with the extra chromium, molybdenum, and vanadium, it would have been a lot better than that.

It's noticably more reactive then M4, Cruwear, rex 45, and 3v.

Academically, should be less reactive then 52100, realistically it seems to rust just as fast in my shop and in use as the 52100. And 4v rusts noticeably faster then the other tool steels.

Deadboxhero wrote: ↑

Sat Sep 15, 2018 7:37 pm

Academically, should be less reactive then 52100, realistically it seems to rust just as fast in my shop and in use as the 52100. And 4v rusts noticeably faster then the other tool steels.

That's interesting. Learn something new every day. :)

Deadboxhero wrote: ↑

Sat Sep 15, 2018 7:37 pm

Academically, should be less reactive then 52100, realistically it seems to rust just as fast in my shop and in use as the 52100. And 4v rusts noticeably faster then the other tool steels.

That's quite fascinating, for me at least.

The ones I made were treated by Peter's Heat Treat. I believe it was an industry standard treatment (high temper) with the addition of cryo between quenching and tempering. The batch's hardness was all 61 HRC.

I may have to do some experimenting, comparing my 4V to some simple carbon steels and 52100 once I get my heat treat oven up and running.

Thanks for the food for thought.

attila wrote: ↑

Sat Sep 15, 2018 7:46 pm

Deadboxhero wrote: ↑

Sat Sep 15, 2018 7:37 pm

Academically, should be less reactive then 52100, realistically it seems to rust just as fast in my shop and in use as the 52100. And 4v rusts noticeably faster then the other tool steels.

That's quite fascinating, for me at least.

The ones I made were treated by Peter's Heat Treat. I believe it was an industry standard treatment (high temper) with the addition of cryo between quenching and tempering. The batch's hardness was all 61 HRC.

I may have to do some experimenting, comparing my 4V to some simple carbon steels and 52100 once I get my heat treat oven up and running.

Thanks for the food for thought.

Ive thought about switching to Cruwear since 4v is so reactive compared to the other tool steels but the 4v is very edge stable even at 64 HRC.



To my surprise 4v can even reach 67hrc.

I've made a Gyuto out of 4v at 64 HRC and it was quite reactive when cutting onions. The Cruwear and hap40 didn't take a patina or react as much as the 4v which was almost instantly.
In my shop, I keep the 52100 and the 4v under a more watchful eye



But I have a solution to the reactivty I'll share soon

Big Chris (outstanding knife maker!) at one time posted on BF that 4V was more prone to rust than M4 or 3V. I don't remember him comparing it to 52100 or similar. My experience with 4V is limited (2 customs), but my 52100 spyderco mili is very prone to rusting but I have never had a rust problem with M4 from spyderco, BM, or others. No problems either with 3V or Cruwear from several makers.

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

This forum needs a like button!

Thanks for the test Deadboxhero!

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.

It depends on the amount of free chromium left in the steel. This depends on the heat treatment. But what also makes a difference is that M4/Rex45/HAP40 have more carbide forming metals in the mix. These steels have quite a bit of tungsten in them to form carbides so more chromium can be left free in the mix. The 4v steel has no tungsten in it at all.

And D2 steel is mostly forming chromium carbides so that is far from being close to stainless level since much of the chromium is being used up. Just looking at a steels chromium level in a composition chart is very deceiving.

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.

You missed Larrins article

https://knifesteelnerds.com/2018/06/11/ ... stainless/

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!