Heat treat coloration difference question

K

KDX

Well-Known Member
Why do they look different? I heat treated these four together tonight in separate triple folded envelopes with a small piece of cardboard in each envelope (tip towards it) and they came out somewhat different looking. All were wiped down with acetone prior to being placed in the envelopes. One envelope was puffed up like a bag of popcorn, but I'm not sure if it was the lite colored one. I tried a file on all of them and it just skated across the blade edge so I guess they are hard enough.

Heattreatcoloration_zpsadfe24fe.jpg
 
Oxide colors after heat treating are not a good way to judge anything. I don't know why some are different than others but there are usually a myriad of variables involved in it.
 
Thanks. I just thought that it was kind of weird. Weird wiggs me out when I'm making stuff and I don't know what happened or why.
 
I agree with John....however, the third one down in the pic raises a red flag to me.....did you by chance have them stacked closely together when heating? I'd need more info, but I tend to trust my instincts, it looks like that 3rd one down didn't reach "temp". (might just be the photo/light)
 
They were in the Evenheat rack that I bought with the oven so I assume they were spaced correctly. This is the first time I've done four stainless blades together. I have four more to do today and will try to remember the order that they are in the rack and see if there is one that stands out like the one above. I put the rack in so the blades edges are below the thermocouple.
 
It might not be....but there have been a few times when I put multiple blades in the oven....the ones placed in the center of the rack came out like that (it appears to have no "color") Through trial and error I finally figured out that I wasn't allowing enough soak time....the exterior blades were getting the soak they needed, but the ones in the middle where not. I extended the soak time 15 mins, and all was well. There are always variables, and I suspect when we read the heat treat recepies on steels, they might not have had more then a single item in the oven at a time. I still use the written recommendations for a single piece in the oven, but for multiples, I generally increase the soak beyond what's recommended. For me, that increase depends on the number of blades I'm heat treating.
 
Thanks for the reply and info. Makes sense. I put these in cold and heat the oven and blades together so it's a lengthy process but the final temp is probably the one that matters the most. These ones I did today the same way. The two wharncliffe styled ones were in the middle. 10 minute soak time.

Batch2heattreat_zpsf287c2a8.jpg
 
Hey. Is anyone on that can help me with my fillet blade steel? We sell a knife with a 420 stainless. Cr13c i think. Chinese steel. It is bending when flexed and I was told this is normal? Help me:)



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hellokombo said:
Hey. Is anyone on that can help me with my fillet blade steel? We sell a knife with a 420 stainless. Cr13c i think. Chinese steel. It is bending when flexed and I was told this is normal? Help me:)



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2 things. a good fillet knife will have some blade flex, helps the blade go over the bones. flex is from blade shape, blade width, and blade thickness not the brand of steel.
 
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