How to Heat Treat 8670

Do you have any theories about why the toughness is lower? It's a big enough difference it would seem like there is something to unpack. Pop's prices for it are so good that it is still very desirable especially for anyone who is learning to forge. While it might not meet the other batch it still performs as well as 1084 and no one complains that it has toughness problems. This makes me really wonder about the bad 15n20 results. It has a reputation for being tough but it didn't hold up with your first test. I am really interested in the new material as well as some if the .25" material out there.
 
Storm W said:
Do you have any theories about why the toughness is lower? It's a big enough difference it would seem like there is something to unpack. Pop's prices for it are so good that it is still very desirable especially for anyone who is learning to forge. While it might not meet the other batch it still performs as well as 1084 and no one complains that it has toughness problems. This makes me really wonder about the bad 15n20 results. It has a reputation for being tough but it didn't hold up with your first test. I am really interested in the new material as well as some if the .25" material out there.
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I can't say why the toughness is lower, it could be multiple things but I would only be guessing. It is important to remember that the toughness is on somewhat of a log scale, however. In other words 10 vs 5 ft lbs is a way bigger difference than 40 vs 35, for example.
 
Larrin said:
I can't say why the toughness is lower, it could be multiple things but I would only be guessing. It is important to remember that the toughness is on somewhat of a log scale, however. In other words 10 vs 5 ft lbs is a way bigger difference than 40 vs 35, for example.
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That's interesting. It makes sense. M4 isn't a high toughness steel but it has even done well in competition choppers. For the way I use knives I have always wondered about the obsession with toughness. For a lack of a better way to say it I guess it seems like a knife only needs enough toughness to achieve its intended purpose but after that it is unused where as extra hardness or wear resistance or edge stability is (mostly) always a better thing. I'm not saying it's not as important just that it isn't as important past a point but maybe that's just my simple mind not understanding the whole thing.
 
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Are you going to do micrographs to see if the steel structure looks different? I’m really curious about the reason for the difference in toughness.
 
Storm W said:
That's interesting. It makes sense. M4 isn't a high toughness steel but it has even done well in competition choppers. For the way I use knives I have always wondered about the obsession with toughness. For a lack of a better way to say it I guess it seems like a knife only needs enough toughness to achieve its intended purpose but after that it is unused where as extra hardness or wear resistance or edge stability is (mostly) always a better thing. I'm not saying it's not as important just that it isn't as important past a point but maybe that's just my simple mind not understanding the whole thing.
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My thinking lines up with yours.
 
Willie71 said:
Are you going to do micrographs to see if the steel structure looks different? I’m really curious about the reason for the difference in toughness.
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I would have to look at several things to try to narrow down the reasons for the difference and I am not sure if the conclusions would be useful enough to warrant prioritizing it over other things. These kinds of investigations are very time consuming.
 
Hey fellas, glad to be here surrounded by so much knowledge. I will be attempting my first knife in a few weeks. I purchased some of pops 8670. I plan to use a small electric kiln to heat treat. My question is regarding “hold” and “soak” times. Once my kiln hits 1500 and I place my knife in the kiln, am I just waiting 10minutes and then pulling it or are we giving the blade time to reach 1500 then soaking for 10 minutes? One more question, I know guys use SS foil to reduce decarb in electric ovens/kilns, could I use an anti scale compound such as ATP641 instead? Thanks guys!
 
CK762 said:
Hey fellas, glad to be here surrounded by so much knowledge. I will be attempting my first knife in a few weeks. I purchased some of pops 8670. I plan to use a small electric kiln to heat treat. My question is regarding “hold” and “soak” times. Once my kiln hits 1500 and I place my knife in the kiln, am I just waiting 10minutes and then pulling it or are we giving the blade time to reach 1500 then soaking for 10 minutes? One more question, I know guys use SS foil to reduce decarb in electric ovens/kilns, could I use an anti scale compound such as ATP641 instead? Thanks guys!
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Wait till the oven comes back up to temp after you put your blade in. Then start your timer.
 
CK762 said:
Hey fellas, glad to be here surrounded by so much knowledge. I will be attempting my first knife in a few weeks. I purchased some of pops 8670. I plan to use a small electric kiln to heat treat. My question is regarding “hold” and “soak” times. Once my kiln hits 1500 and I place my knife in the kiln, am I just waiting 10minutes and then pulling it or are we giving the blade time to reach 1500 then soaking for 10 minutes? One more question, I know guys use SS foil to reduce decarb in electric ovens/kilns, could I use an anti scale compound such as ATP641 instead? Thanks guys!
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Yes you can use anti scale instead. I don’t used foil when oil quenching.
 
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