Knifemaker.ca
Dealer - Purveyor
This is like a thread on ex-wives. It's important to know, but trying to understand will just make your head hurt. :biggrin:
Ok, Ed, I do understand your position that you are progressively adding more carbon into solution to form adequate martensite to harden the blade. My concern is that with each subsequent quench you are also stressing the steel and forming more microscopic cracks with the plate martensite, which is 100% with the carbon content found in 52100. My feeling is that it is better to shorten the soak time, do it once, and stress the steel once with a single quench. Of course this would take a scanning electron microscope to test completely.
Doug
Hi guys
I made up 3 little EDC skinner knives for me and two buddies of mine for a recent hunting trip. The knives worked well on the one buck we killed but after we have been back i just dont feel like these 3 knives hold a edge as long as they should.
HT info is as follows
Normalized by heating to 1675deg and air cool, then 1550 deg and air cool, then 1475deg and air cool.
Triple quench by heating to 1490deg and holding for 4 min then edge quenching in canola oil heated to 150deg. I did this process 3 times in a row with the blades cooling in the oil, i did not let them rest over night, all three heat treats were done back to back.
I tempered them twice at 350deg.
I tried to do a edge flex test over a brass rod and after having to push VERY hard i think the blade has flexed just a little but not gone back to straight, there seem to be just the smallest bend to the cutting edge.
A previous knife i had done a triple quench with while letting it rest overnight in my freezer in between each heat treat seems to hold a sharp edge for ever. and a single quench blade i did holds a great edge, i chopped down about 15 cedar limbs and it would still pull hair afterwards.
These knives just dont seem to hold the same edge as the previous blades. all of these knives are 52100 steel from ALdo. On these 3 knives i ground them down a little thinner than i normally have before heat treat, could this be carbon loss on the cutting edge ??
any ideas ??
thanks
steve
Lerch,
sounds like your blade did not reach full hardness during the quenches, or your tempering oven is WAY off if you tempered it at 350 and the edge stayed bent during your brass rod test.
you said that you quenched 3 times back to back. were you doing just the one knife or several? what was the temp of your oil at the time of the last quench? could be that your oil was too hot to cool the steel right. also how old is your canola? could it have broken down over time and not be quenching correctly? or could it have been contaminated?
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