Alloy banding in A2?

[aarongough]

Hey guys!
I'm finishing up a batch of 7 blades at the moment, all made from A2. The steel is from 2 separate suppliers and I'm seeing alloy banding in both batches of steel. One lot of steel (bought a sheet!) was from Starret, the other lot was from Jantz Supply.

Here's a picture of the banding, I acid etched the blade in ferric chloride to make the banding more obvious:

Don't mind the abused and poorly finished test blade!

This banding barely shows up even if you look closely when the steel is satin finished, but it's obviously unusable for an acid etched finish.

Anyone else seen this in A2? Is this an issue with A2 from all manufacturers? I would have thought Starret would be making pretty clean steel...

Edit: it should be noted that I can see the banding both before and after heat-treat, so I don't think it's something I'm introducing.

 

[mete]

Starrett never made steel, they buy it. Starrett now farms out their saw blades and micrometers !! Lower quality now. If those white specks are carbides that you can see that easily it's poor steel !! Find another supplier .

 

[aarongough]

Starrett never made steel, they buy it. Starrett now farms out their saw blades and micrometers !! Lower quality now. If those white specks are carbides that you can see that easily it's poor steel !! Find another supplier .

Gotcha, should have realized that Starret bought it.

The patches look to me like areas of higher chromium concentration, I don't have a microscope good enough to do any better than that kind of guesswork unfortunately.

 

[aarongough]

As a a quick follow-up: I just talked to Starret USA about this issue, and they're getting me to send in a sample to they can section it and have a look. The guy I talked to seemed helpful, so we'll see where it goes from here.

I'm going to have to do more testing on a sacrificial blade and see if the banding is having any functional effect on it's properties.

 

[Stacy E. Apelt - Bladesmith]

I stopped using A-2 years ago because it almost always had alloy bands. I thought it was just me and my HT.
It probably didn't matter much in the blade quality, buy was a detraction in the looks.

I switched to 154-CM and then to CPM-154 with no problems. I know A-2 makes a great blade, and maybe there is a difference between suppliers. Mine was from Mick Koval, IIRC. ( Or maybe from Admiral??)

 

[aarongough]

I stopped using A-2 years ago because it almost always had alloy bands. I thought it was just me and my HT.
It probably didn't matter much in the blade quality, buy was a detraction in the looks.

I switched to 154-CM and then to CPM-154 with no problems. I know A-2 makes a great blade, and maybe there is a difference between suppliers. Mine was from Mick Koval, IIRC. ( Or maybe from Admiral??)

Thanks for the input Stacy.

I guess that's good news and bad news. Good news in that likely I don't have steel that's unusable. Good news in that I'm likely doing nothing wrong.

Bad news in that I may have to find a new steel. We'll see I guess.

I spent the morning on the phone with Starrett USA, and also with a metallurgist from the Canadian office of Uddehölm. The guy from Uddeholm said that he hasn't heard of issues like that with A2, but as he pointed out that doesn't mean it didn't happen, just that it possibly wasn't a problem for other users (who are possibly less demanding than we are in terms of aesthetics).

Kinda makes me wish they made a powder version of A2, just for the cleanliness and homogeneity benefits.

 

[james terrio]

Kinda makes me wish they made a powder version of A2, just for the cleanliness and homogeneity benefits.

Why use A2 at all? 3V is tougher, holds an edge longer, and isn't as difficult to work with as people like to make it sound. It is a little more expensive and a bit harder to sharpen, but it's certainly cleaner.

 

[aarongough]

Why use A2 at all? 3V is tougher, holds an edge longer, and isn't as difficult to work with as people like to make it sound. It is a little more expensive and a bit harder to sharpen, but it's certainly cleaner.

Yeah, that's a good point. In my testing I found the performance difference between A2 and CPM3V to be pretty small. The cost of 3V is about 3x that of A2, and A2 is available in a good variety of precision ground sizes whereas 3V is not. The availability was the clinching factor for me given all the other factors.

With that said, if I can't get a decent finish reliably from A2 then obviously I'll be changing to something else. Shame really as I feel that I'm really doing a good job on the heat treat for my A2 and a bunch of work has gone into getting it there...

I have some pieces of A2 supplied by Uddeholm kicking around the shop. I'm going to cut those up and etch them to see if there's any banding in them.

If I start looking at other steels because of this then I'll likely want to have a look at Vanadis 4Extra as well. It would be nice to work with Uddeholm as my steel supplier as they have a big office right near where I live and everyone there is very helpful.

We'll see how the testing goes on the current batch of A2 I guess. At least once knife will have to be re-made given that it's supposed to be acid-etched.

 

[Matthew Gregory]

If I start looking at other steels because of this then I'll likely want to have a look at Vanadis 4Extra as well. It would be nice to work with Uddeholm as my steel supplier as they have a big office right near where I live and everyone there is very helpful.

Sometimes forming relationships with folks in the industry can be very beneficial. Might be a good idea to let them have a 'face with your name', if you follow me.

Vanadis 4e is even more difficult to come by than 3v. Perhaps you might consider CPM4v, which has a comparable chemistry but an older PM technique. Niagara Specialty Metal had a lot of it, when is was last there, and I'm convinced it'll be my never favorite steel when I start doing cryo in-house.

I'm in agreement with Jimmie T on this one, too - my experience with 3v was considerably better than with A2. Perhaps your heat treat process wasn't optimized for it...?

 

[AVigil]

Why use A2 at all? 3V is tougher, holds an edge longer, and isn't as difficult to work with as people like to make it sound. It is a little more expensive and a bit harder to sharpen, but it's certainly cleaner.

"A little more expensive?" I can get a bar of A2 3/16" 1.25" wide and 36" long for $39

The same dimensions in 3v from Aldo is $251

A2 has a long history of being highly successful in knifemaking for good reason.

3V being a good knife steel does not take anything away from A2 blade.

A sharp blade in A2 is a wonderous thing

 

[DCL Knives]

"A little more expensive?" I can get a bar of A2 3/16" 1.25" wide and 36" long for $39

The same dimensions in 3v from Aldo is $251

A2 has a long history of being highly successful in knifemaking for good reason.

3V being a good knife steel does not take anything away from A2 blade.

A sharp blade in A2 is a wonderous thing

Something is funny with that price on Aldos sight, probably because it's always out of stock. When it was last in stock I think I purchased that size for under $70. 3v is more expensive but not THAT much more.

 

[AVigil]

Something is funny with that price on Aldos sight, probably because it's always out of stock. When it was last in stock I think I purchased that size for under $70. 3v is more expensive but not THAT much more.

Thats good to know. His price on the website is just crazy

 

[ChristoDart]

I noticed a lot of the out if stock items have recently changed in price on Aldo's website. In my past experience these prices do not reflect the price that they sell for when in stock. A little confusing though.

 

[aarongough]

Sometimes forming relationships with folks in the industry can be very beneficial. Might be a good idea to let them have a 'face with your name', if you follow me.

Vanadis 4e is even more difficult to come by than 3v. Perhaps you might consider CPM4v, which has a comparable chemistry but an older PM technique. Niagara Specialty Metal had a lot of it, when is was last there, and I'm convinced it'll be my never favorite steel when I start doing cryo in-house.

I'm in agreement with Jimmie T on this one, too - my experience with 3v was considerably better than with A2. Perhaps your heat treat process wasn't optimized for it...?

Bummer if Vanadis 4E is that hard to come by then that would be a real pain too. If A2 doesn't pan out then I'll have to explore the options. I don't want to give up on it too quick though!

As I said, I feel I've really nailed my HT for A2, would be a shame to ditch all that work. I won't hang onto it beyond good reason though!

I totally agree about knowing people at the suppliers. The guys as Uddeholm have been great so far, hopefully their A2 will be cleaner!

"A little more expensive?" I can get a bar of A2 3/16" 1.25" wide and 36" long for $39

The same dimensions in 3v from Aldo is $251

A2 has a long history of being highly successful in knifemaking for good reason.

3V being a good knife steel does not take anything away from A2 blade.

A sharp blade in A2 is a wonderous thing

I buy a 5/32x6x36" precision ground sheet of A2 for around $180. The same size sheet in CPM3V (in a non-precision-ground sheet) costs $640. If I wanted that sheet precision ground then the cost would be even higher...

That said if CPM3V ends up being the answer then that'll be what I do! I want to investigate the options for A2 first though.

I totally agree with what you said about A2. A good thin blade made from A2 at 62HRC is a thing to behold!

 

[Kloepper Knife Works]

Bummer if Vanadis 4E is that hard to come by then that would be a real pain too. If A2 doesn't pan out then I'll have to explore the options. I don't want to give up on it too quick though!

As I said, I feel I've really nailed my HT for A2, would be a shame to ditch all that work. I won't hang onto it beyond good reason though!

I totally agree about knowing people at the suppliers. The guys as Uddeholm have been great so far, hopefully their A2 will be cleaner!



I buy a 5/32x6x36" precision ground sheet of A2 for around $180. The same size sheet in CPM3V (in a non-precision-ground sheet) costs $640. If I wanted that sheet precision ground then the cost would be even higher...

That said if CPM3V ends up being the answer then that'll be what I do! I want to investigate the options for A2 first though.

I totally agree with what you said about A2. A good thin blade made from A2 at 62HRC is a thing to behold!

I purchased a 24"x36"x5/32" (oversized @ around 0.182", not ground) sheet of CPM 3V a little over a month ago and it cost $700 from NSM. The same sheet belt ground was around $900 if I remember correctly.

Crazy prices being thrown around here.

 

[Kloepper Knife Works]

Just checked the NSM website. Descaled, sheared, oversized 5/32", CPM 3V, 6"x36": $318

 

[james terrio]

A2 has a long history of being highly successful in knifemaking for good reason.

No question about that! So does 440C... but when I started having trouble finding good clean bars of it (which was immediately), I turned my back on it and never looked back. Especially not when there are several options that are nice and clean, and readily available.

I have plenty of work to do with every other controllable factor that goes into making a blade, I'm simply not gonna fool around with banding and inclusions and weird finishes I can't do anything about.

One of the hardest lessons I learned in this game was to not put so much stock in cost/square inch of materials. I'm not running a factory trying to crank out thousands of blades a month.

I'm not knocking any particular alloy. By all means, use whatever you like. More than one way to skin a cat, as they say...

 

[aarongough]

I purchased a 24"x36"x5/32" (oversized @ around 0.182", not ground) sheet of CPM 3V a little over a month ago and it cost $700 from NSM. The same sheet belt ground was around $900 if I remember correctly.

Crazy prices being thrown around here.

The $640 price I gave was from the NSM website, for belt-ground and saw cut .186x6x36" which was the closest sheet size I could find to what I normally use.

The price you quoted is not shown on their website anywhere as far as I can see. Was that a 'full sheet' price?

For me having the stock come precision ground is a real plus as I don't want to be dealing with stock of different thicknesses, and flat grinding on the grinder is very inefficient compared to paying the supplier to do it. I really wish NSM would do precision grinding, rather than their belt grinding.

 

[aarongough]

No question about that! So does 440C... but when I started having trouble finding good clean bars of it (which was immediately), I turned my back on it and never looked back. Especially not when there are several options that are nice and clean, and readily available.

I have plenty of work to do with every other controllable factor that goes into making a blade, I'm simply not gonna fool around with banding and inclusions and weird finishes I can't do anything about.

One of the hardest lessons I learned in this game was to not put so much stock in cost/square inch of materials. I'm not running a factory trying to crank out thousands of blades a month.

I'm not knocking any particular alloy. By all means, use whatever you like. More than one way to skin a cat, as they say...

I really agree with what you're saying here. For me one thing I didn't want to deal with was the varying thickness of non-precision-ground stock. Now if banding is going to be an unavoidable problem with A2 then that probably trumps the issues with 3V. I'm definitely a control freak when I'm at the shop. I want everything squared away!

 

[james terrio]

I'm definitely a control freak when I'm at the shop. I want everything squared away!

Me too. Life is just too short to muck about with mill scale and weird sizes and whatnot.

Whenever possible I get my stock from Aldo (NJSB) and pay him a little extra to surface-grind it. Chuck (AKS) often has nicely ground stock as well. Works for me. I don't know if that's precise enough for your purposes, you'd have to talk to them about that.