Soft/hard after ht

Roger

Well-Known Member
I was experimenting with heat treating last night and had a problem I don't understand. I was using old truck coil spring. It had been flattened to about 3/16. I tried it at different temperatures and quenching in canola and water. Each time after taking off the scale I could use a file and just file away on it, like it was mild steel. I put it in the vise and wacked it and snap it broke. Trying to file 'inside' the steel at the break it was hard as hell. Did it only harden 'inside'?

I had some O1 and took it up to really red and poked it into the water barrel as a quick test. It was hard as hell inside and out.

Is it time for me to give up on free material? :)
 
"Free" is hard to pass up, but the ability to accurately heat treat a blade is priceless. Steel isn't cheap, but if you are letting blades leave your shop it is crucial to know that your heat treat is the best you can provide. I would hate to think I "guesstimated" the heat treat of a blade and it failed the owner when it was needed most.
 
junk/unknown steel is good to practice forging with but when it come to heat treating you need to know what you have to reliably produce the same results every time. It could be you had a lot of decarb on the surface so if you ground the top layer off you would be into the harder steel just a guess ...steve
 
Thanks for the feedback, I'll keep practicing. Murph, you don't have to worry about inferior product tainting the image of legitimate knife makers. My efforts are 100% hobby related.
 
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