Is this alloy banding?

samuraistuart

samuraistuart

Joined
Dec 21, 2006
Messages
3,158
I know the pics are just not going to show you what I'm seeing on this blade, I tried the best I could to photograph this affect. Above the edge, you can just make out a line that is horizontal, and there are other lines as well that I couldn't get to show in the photo. All lines are horizontal, oriented from ricasso to tip. Yeah, the term "orange peel" does come to mind. Seems like the lines are sanding out. Came across this before heat treating other knives (come to think of it...all 1084).. I'm fairly certain this is alloy banding, what do you think? All three blades I'm working on show it. Steel was Aldo's 1/8" 1084. Heat treat in kiln 1500F for 10 minutes total, (5 to come to temp, five to soak), then cool to black. Then 1400F for 10 minutes, cool to black. Then 1500F for 10 minutes, very quickly into Parks 50 for 10 slow seconds, cool to room temp. Temper at 360 for hour and a half, cool to room temp. Temper at 410 for an hour and a half, cool to room temp. I had done a larger blade of AKS 1080+ with the exact same heat treat, but only did one cycle of 1500F (didn't do the 1400F). Same quenching temp, quench and temper as the 1084....but no banding whatsoever. The only two variables being the steel type (1084 vs 1080+), and the second normalizing step with the 1084 not done with 1080+. I did a little research, and came to the conclusion that this is just part of the steels chemistry, but I can't control it...so it bugs me!!! Can I control it? Muchas Gracias!SAM_1205.jpgSAM_1204.jpg
 
I really can't see from the pics. Too dull. If it is alloy banding, it won't sand out- you'll be able to see it more clearly at 600 or so but only at a certain angle in a certain light. An etch will really make it stand out.

It can actually be manipulated for some cool effects.
 
I've only seen it on 5160 and 52100, though I'm sure it's possible with other steels. It looks good when taken to a fine finish and etched and lightly buffed. Think of it as poor man's wootz. The only time I see it on my my blades is when I've done a good bit of low temp forging and thermal cycling, and blades with a fine pattern cut better than ones without, and are very tough. Possibly the reason I haven't seen it on 1084 or other steels is I don't have any real thick pieces and don't spend as much time forging. Will have to try some L6 sometime and see if I can get it to do it.
 
Thanks guys for replying. I know....you can't tell jack from the pics. The "banding" sands out. I just finished 120 grit, and it isn't there any more. My guess now is just simple decarb. What had me going is the pattern it formed. All lines running from ricasso to tip, kind of tightly packed together. So, nope, gotta say not alloy banding, just a cool looking decarb pattern.
 
Could it be de-carb? Are you going back to the grinder after heat treat? If you are, and IF it is de-carb, then it should clear up with the grinder.

Robert
 
Thanks Robert, you and I posted almost at the same time. Yeah, I'm pretty sure it is decarb, since it sanded out. I am under the impression that actual alloy banding cannot be sanded out, but is part of the steel's structure. The decarb layer that formed on the 1080+ knife that I was working on at the same time did NOT form straight lines that ran from Ricasso to tip, but more of a random orange peel look that also sanded out fairly quickly. The decarb layer I was dealing with on a CFV blade was much deeper, and didn't really give a pattern, just a layer of .010 of decarb to get through before reaching hard steel. Of course, the heat treat on that alloy requires longer soaking times (and higher normalizing temps) because of the alloying content, so one would expect more decarb there than simple carbon steels like 1084 1080+.
 
When did you get that 1084 from Aldo? He had a bad batch about 3yrs ago that gave the same symptoms.
 
Hey Rick, the "banding" indeed sanded out, so that has me pretty confident it was just a decarb layer that looked like banding. After 120 grit you couldn't see it, and after 220 grit it is totally gone.
 
Good news... Aldo's tainted batch was bad all the way through, so I don't think you got it. BTW, he completely replaced all the steel and then some for the trouble. He's a real stand-up guy.
 
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