Vanadis 4e heat treat

not questioning your results, just clarifying one point for those who are newer at heat treating. Sub zero is not cold enough for full conversion of retained austenite with this group of steels. You need full cryo. Well, you need to get last -140f, which sub zero does not.

Your testing confirms that heat treating must be tailored to the application. There are advantages/disadvantages to high and low temper. High temper has better wear resistance at the expense of some toughness. I make mostly kitchen knives and thin slicers, where the increased toughness and smaller carbides are an advantage. Chris is using an application where wear resistance is more important. Heat treat to your application.

 

Retained Austenite is not a BAD thing!!

Liquid Nitrogen is also NOT required in knife making to make a functional knife!!

These are two statements that I feel new makers need to hear also!

 

If you are using the upper temper with your steel then you are eliminating most of the retained austenite.

 

there are a lot of caveats that go along with those statements. I don’t disagree with your statements, but how much retained austenite is ok, in what application? There is no denying that sub zero will work, mostly, but cryo gets full conversion, rather than partial. My testing has shown cryo to be superior with this group of steels. Others have not shown as much difference.

I have recommended many times before that if you don’t have cryo, use high temper with this group of steels. You came to the same conclusion.

 

I have to ask since we don't get many blade sports guys on here and it is something that I want to get into. It seems like V4E is more popular now than CPM M4, why the shift?

Sorry for the derail.

 

I'm going to chime in here because this is a subject matter I'm pretty close to. We're having a pretty good year in Bladesports this season with Ben undefeated and Jo taking all but one of her events using knives we made in V4E at HRC 63.5.

We did exhaustive testing on steel and heat treat variations. There are two important takeaways that can be applied by every knife maker here using V4E or CPM 4V.

1: The performance difference between V4E and 4V is vanishingly small. Within a margin of error. I've used a bunch of both. We will probably switch to 4V in the future because having a custom run of steel made in America made to my specified condition and gauge is way better than importing plates of steel from Europe and there is no practical difference in testing or in use.

2: The heat treat using the secondary hardening hump has lower edge stability than a proper low temper tweak. By proper I mean the quench rate and timing into cryo is done right. Mess up this step and your results can be worse than simply using the secondary hardening to address RA. Controlled testing with identical geometry and test media has proven to me across a range of hardness that this approach to HT is the right approach to 4V in a knife application. The high temper on 4V and V4E leads to a somewhat chippy crumbly edge compared to an optimized low temp tweak, which requires a more obtuse edge angle to compensate.

We run the heat treat that we developed but found that the process used by Peter's is similar and gives similar results. This means you can send your 4V or V4E to Peter's, ask for the low temp tweak, and you can get something about as good as the knives that we compete with. Brad at Peters is not leaving performance on the table.

My thoughts about steel and Blade sports:
A failed cut can easily mean the difference between winning and losing. Knives are run pretty thin in Bladesports to get through the boards with fewer hits and to maximize your odds of cutting the straws and hanging rope (you get one attempt) without taking damage in the dowel and 2X4s. If you take damage that's a deduction. So it's a balancing act with edge geometry and primary grind thickness run as thin as possible but not too thin. (and too thin depends a lot on the skill of the cutter). As a rule, the harder you run the steel - the higher the yield point - the better your odds the distortion in the bevel from a wonky cut will bounce back rather than take a set. These knives are thin and hard. 4V is more durable than M4 at this hardness in these geometries because it resists chipping at the higher hardness that works best to avoid bends, which allows you to go thinner. That doesn't mean that 4V and V4E is the ultimate knife steel, it's just the best performing in this application that we have figured out yet.

 

I wouldn't use 4V for that, I would use 3V at 60-61

 

Thanks for taking the time to answer. I have to ask, why would you prefer 3V for a hard use knife?

Also I bought some .25 A2 for some practice choppers and I have a piece of .30 CPM M4 for my first real competition chopper. Have you worked with it much? Do you have any advice about high vs low temper in it? I'm assuming that these knives are not ground after heat treatment so what's the best options for quenching? I really enjoy this spectrum of steels and want to give the 4V a try soon.

 

You want durability in a hard-use knife. The ability to shrug off rough use without damage, and a large margin for error so it won't fail. Durability in a knife is a combination of strength and toughness (speaking of metallurgy, excluding geometry). Strength and toughness are properties that are at odds with each other. Although 4V is very strong, 3V is nearly as strong and has better ductility (higher toughness) which allows it to spread a concentrated force across a larger area through localized yielding that would break a more brittle alloy. So it takes a lot of force to break 4V, but it takes a lot of energy to break 3V. 4V has a brittle failure mode where it doesn't actually take that much energy to break it. Practically speaking it is very difficult to actually break 3V.

 

Hey guys,
thanks for all the information you put out there! I got my hands on some v4e and now I wonder what heat treatment leads to the sweetspot hardness/toughness?
I thought simething like 30 min at 1030°C, then cryo and temper at 200°C. The cryo should take care of the retained austentite, so would it make sense to temper multiple times?
Also, i am open to suggestions

 

1975f, plate quench, cryo for 1h, 400f temper x2, preferably 3 will get you an awesome tough knife at Rc63/64. Not 3v or z-tuff tough though. This will be tougher than 1095/01 at Rc58. Use 1/2 the edge thickness or less than what you would with a simple steel.

we don’t have the curve plotted yet. We have a soft and hard sample tested so far, but the samples in between are waiting grinding. The soft sample gained less toughness than z-wear did when going softer, which gained less toughness than 3v. I’m using z-tuff up to Rc62, z-wear to Rc64/65, and V4e at Rc64+. I have more experience with z-wear, and am really comfortable with geometry recommendations with it. I’ve only done a few V4e knives so far, so I’m not as sure about how thin I can go with it.

 

I’m quenching at full thickness. You need a fast quench in the first half. This is not easy on belts.

 

Awesome, that's exactly what i was looking for. Thanks a lot!
Z-wear and z-tuff look also very interesting. But getting steels like these in germany can be a real pain...

 

have you tried RSAlloys?

 

I’ve ordered from germany to Canada and shipping was reasonable. Alpha Knife Supply has these steels, and is great to deal with. I’m sure they would ship to Germany.

 

Hey guys, thanks for the tipps!
The biggest problem is, that i only need small quantities and that is not interesting to the "big players". Often i did not even get a reply, when I asked if they sell smaller quantities.
I have not tried RSAlloys yet, but i certainly will.
The problem with AKS is the new european data protection law (https://www.alphaknifesupply.com/access-denied.htm). Ok, it is not a big problem, but it involves extra steps, just to access the site, but probably I will try anyway
Thanks again for the help!