CPM S30V Overheat

J

John L

Joined
Oct 28, 2004
Messages
1,330
I heated to 2000 for 15 minutes. Tempered at 600 for two hrs. Tempered again for two hrs....then ..I guess I had misprogrammed my evenheat...and I ramped up again to 2000. So...I figure I would just temper again twice at 600. .....You guessed it..it ramped again up to 2000 after two tempers at 600. Gees..You'd think I would learn. Can I temper again or just scrap it?
 
I think I would redo the heat treat. 15 minutes sounds okay for the soak. I soak S30V at 1950 F. and temper at a lesser temperature. But if you've been having good results .....

rlinger
 
John L said:
I heated to 2000 for 15 minutes. Tempered at 600 for two hrs. Tempered again for two hrs....then ..I guess I had misprogrammed my evenheat...and I ramped up again to 2000. So...I figure I would just temper again twice at 600. .....You guessed it..it ramped again up to 2000 after two tempers at 600. Gees..You'd think I would learn. Can I temper again or just scrap it?
Click to expand...

Was it still in the foil during all this? If so, I agree with Roger in that you should just normalize and re-treat.
 
Hello Scott: Thanks very much for your offer..but I don't expect you to cover my mistakes. Very nice offer however. Thanks again. I finished the knife today and have been cutting up a storm ever since and seems to be fine.
 
John, Let us know how the blade performs long term ---this is interesting. Did you do a cryo cycle on it ? I have found S30V to be very forgiving and it is hard to blow the grains on this one. The other day I was heat treating and working on another project at the same time and forgot I had a blade in the furnace. This one was S90V and it got soaked for 4 hours at 2150. I figured that one is scrap --and it is-- as far as a blade to sell. So I decided to do a little testing with it. I clamped the tang in a vice and hit the blade a pretty good whack with a hammer. I expected it to break but it just went boing. I then ground some off to see if I could see any unusal grain structure, again it looked normal. I did a hardness test and it was RC 62, So far so good so I put it in the LN2 overnight and did a temper at 400. I came down to 60, just like you would expect for a normal heat treat. I will finish it into a useable knife and give it some more testing. Again I can't sell it but can maybe gain some more information on this class steel. After this radical soak it still seems to be just as tough and hard as a normal heat treat. It amazed me.. PHIL
 
Phil, I realize you have extremely high standards, but if the blade passed all your tests and Rockwells fine, what's the problem with selling it?
 
Phil: I did not cryo it as I have now good way to do it yet. Maybe later. Blade seems to be holding up fine. I opened some huge cardboard boxes with it over the weekend and I can't really tell the difference between the first and the fifth box...maybe a tiotal of 60-70 lineal feet of cutting. Who knows?
 
Danbo, This blade is so far out side of the normal soak time that it would be a risk to give it to a customer. If I had a lab where I could look at the microstructure then it would be different. I will keep it for myself, use it hard around the shop and maybe learn from this. It doesn't take much time to rough grind a new blade and heat treat it right. Phil
 
Danbo and all, I did some more work on the 4 hr blade. I surface ground off about .020 on one side and did another hardness test. hardness is 55. The first tests were done on the original ground surface and they were 5 points higher. somehow with the very long soak the surface got harder than the center part. Anyhow the blade is confirmed junk now. PHIL
 
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