Sticking HT foil?

[andy gascoigne]

Has anyone come across this problem? Yesterday I did a heat treatment on a D2 folder blade. I put the blade in a stainless steel, foil HT envelope. I placed the envelope in the pre heated furnace at 1850oF and let it soak for 20mins. When I removed the package from the furnace I found that some of the HT foil had bonded it'self to the blade, some just pulled of but a lot of the foil had to be ground back. I was fortunate that I had left some thickness in the blade for cleaning up.

I have used these foil envelopes before an have never had this problem...Any ideas?

Andy..

[polarbearforge]

We've had that problem when heat treating higher temperature schtuff at work. Usually we dust what ever is being heat treated with talcum powder. It's inert material that prevents the foil from sticking.

Jamie

[andy gascoigne]

Originally Posted by polarbearforge

We've had that problem when heat treating higher temperature schtuff at work. Usually we dust what ever is being heat treated with talcum powder. It's inert material that prevents the foil from sticking.

Jamie

Thanks Jamie, Ill give it a try next time. This was the only time I did'nt put a piece of paper in the envelope to burn of any oxygen left in the envelope. maybe the paper prevented the foil sticking before.


Andy..

[SVanderkolff]

I have had the same problem, usually when I get most of the air out of the bag before heat tret. I think that if the foil is sucked up against the blade as it heats up then you will get the sticking. By putting even a little piece of paper in the envelope you will create some smake and there fore keep the foil from getting sucked onto the blade. Not the clearest explaination but hoippefully you get the idea.
Steve

[RJ Martin]

Andy: It seems that the foil tends to stick when the blades are extremely clean. I do not personally like to add anything combustible inside the packet, and, I like the least amount of air in the packet as well. So, I'd vote for the talcum powder. I have used that over the years with fine results.

[andy gascoigne]

Thanks Steve and RJ.. I did clean the blade real good and also squeezed as much air out as possible.

I'll use the talc powder next time.

Andy..

[Don Robinson]

I've had that happen a few times too, and never knew what causes it.

I clean the blade with alcohol before sealing it in foil, so RJ may be right about being too clean.

I used to put a corner of a paper towel in the package, but stopped doing that some time ago. It doesn't seem to make a difference as far as I can see. The oxygen in the package has to burn off anyway.

Talcum powder, huh?

Thanks for the tip.

[SVanderkolff]

Thanks Jamie
I will give the talcum a try as well.
Steve