H/T question Paul HELP!!!!!

R Dockrell

R Dockrell

Joined
Mar 26, 2000
Messages
658
On the weekend I did a HT of a batch of blades. One was a ATS-34 fillet knife with a 10 inch blade. Tempered it at 925 F RC59.
The problem is that I didn't notice but it has a long slow curve in it.
I have tried the brass pins and vice trick. I have even clamped it betweened wood in the vice and bent hell out of it by hand with gloves on. No change still a long slow curve.
Can I heat it in the oven or in the tempering salts to about 450F for 10 or 15 minites then straighten it hot without effecting the temper? How hot for how much time can I safely go?

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Robert
Flat Land Knife Works
rdblad@telusplanet.net
http://members.tripod.com/knifeworks/index.html
 
Robert: Call Paul Bos. He is the world's best heat treater, and also the world's slowest typist. A quick call will fix you up. I'll see if I can dig up the ## for you.

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"Come What May..."
 
Dont look at me, I had the same problem with a 7" fillet blade. It was straight when it went into the liquid nitrogen but pointed south when it came out. I tempered it anyway and finally opened a drawer and put the tip in with some rubber padding on the drawer edge. I put my big gloves on and face shield and started flexing it. It went almost to 90 degrees before it got straight. That ATS is tuff stuff, I thought for sure it would break. It rockwell tested at 59 if it was 61 I think it would have broken. Im waiting for Paul Bos on this one with you. Bruce B
 
Hi Rob,

Easy solution on this one. You can just re heat treat the blade and then straighten it out again. You do not need to aneal it.

The thing is that with some steels (there is a word for this, but can't remember) multiple heattreats will not affect the martensite structure in the steel, or subsequent performance.

Personally I have heat treated, quenched and tempered a blade of ATS 34 and BG 42 for 3 time, with no noticable ill effects (whitout anealing). ATS 34 has slight surface change, that resembes Wootz to a degree. RC was a consistant 60 with the ATS 34 and 62 with the BG 42.

As you know I am using salts too. One has to ensure temperatures are bang on and soaking times don't need to be as long as the first time you do your HT.

Hope this is clear enough.

Thomas




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Haslinger Custom Knives
WWW.HASLINGER-KNIVES.COM
thknives@home.com
 
Rob: Thomas is right, I would re H. T. Clamp blade between 2 bars Run your Cryo. and temper @400 Deg. F for 2 hrs. cool to room temp. take out of clamps, Then do your double temper @950. Hope this works. Paul.
 
As a final side note on this post.

The clamp worked to perfection and the blade is perfectly straight. I used two chunks of 2X2X.25 angle as clamp bars.

The only problem encoutered is of concern to those that use salt for there HT. I strongly sugjest a quick wipe to remove any molton salt from the blade BEFORE you clamp the blade between the peices of metal. What happens if you don't is the liquid salt hardens as it touches the cold steel bars of the clamp. As you tighten the C clamps around the hot blade and the metal bars the metal bars squeeze the hard little bits of salt into the hot soft blade metal.
This leaves you with a blade that has a few dimples in it that will require a little extra to smooth out but the blade is straight.
So I beleive that a quick wipe down will solve the salt dimple problem.
This process might also be used to straighten or keep straight radically ground blades.

Once again thanks Paul.

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Robert
Flat Land Knife Works
rdblad@telusplanet.net
http://members.tripod.com/knifeworks/index.html
 
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