Avoiding Alloy Banding

[M.Griffin]

I have been having a problem with some patchy alloy banding on the last few blades I have finished lately. This has only occured since I have tried to upgrade my heat treating operation. I have a thermocouple to know my temps and am quenching in Parks 50.

Here is my heat treating process:
1. Normalize hot on the first one (~1600) and the next two progressively cooler.
2. Heat to 1525 and soak for 3-5 minutes
3. Quench in Parks 50
4. 3 temper cycles at 1 hr each

I am using 1095 and would like to solve this issue. It doesn't show so much on a fully hardened blade with no etch (though you can see it in the right light), but when I clay coat and etch for a hamon, the alloy banding shows and I just can't like it. The weird thing is that is shows up in different spots on the blade. This tells me that my heat is not as even as it should be, but is there something more to it? Thanks.

-Mike

 

[JasonSCarter]

Your temps are too high. normalize and soak at about 1100 - 1250ºF then ramp it up to 1475 to quench make sure the temp is even across the whole blade, the way I check for this is by sprinkling table salt across the blade. Then since it melts at the magic temp of 1475ºF I watch for it to start melting. when it does I give it an extra 15-30 seconds then quench. Also you might check the "Hypereutectoid" sticky by Kevin Cashen, it will educate you greatly on how to deal with 1095/W series.

Jason

 

[jdm61]

Try a longer soak.

 

[Mike Krall]

Mike,

Heat Treater's Guide has 1095 normalizing at 1570F (aerospace practice is 1550F) with austenitizing at 1475F for both industry and aerospace. Soaking 10min. is probably a better standard though 5min. for some steels is fine. All the heating needs to be done evenly. I do two tempers of 2hrs. each.

I've come across a few discussions the past couple of years about 1095 having alloy banding. People have found it when they finished out a piece of the as-delivered flat stock. I don't know that there are processes a knife maker can do that will change that. A person can switch to W1 and get tool steel spec. metal to work with... it won't have alloy banding.

Mike

 

[M.Griffin]

Thanks for the input. After forging, I did "anneal" it in vermiculite. Now I read that this is a bad choice for 1095 and may have lead to my banding problems even with normalization. Man, there is a lot to learn. Thanks again.

-Mike