heat treatment

M

manwithnoname

Joined
Nov 29, 2006
Messages
6
ok i started a new project.....
i started out with a coil spring (from a car volvo i think) blacksmithed it to the shape i wanted and semi polished it.... now to the question; when heat treating i heated it to a dull red and checked it with a magnet to see if it had infact demaged.... when i quenched it it came out with a nice gun blue like finish (all except where i touched it with the magnet)...... anyone know why this is? what happened? i plan to do it over and see if my results improve.... thanks in advance guys/ gals ....
 
You probably have a lot of decarb and scale on it post-quench. Grind off all the decarb and scale and test the blade. My guess is that you simply scraped off some scale with the magnet and it looks different. Youll need to take at least the skin of scaled and decarbed metal off the knife post-ht after tempering.
 
Welcome to Bladeforums!

moving-van.jpg
 
I think the magnet leeched some of the heat out of that area, that would lower the temprature enough for it not to form scale in that spot.

Just my 2 cents
 
Was the blade fully hardened? It shouldn't be a pretty blue. It should be an ugly bluish-black. The time from reaching the proper temperature to quench is VERY short. You may have spent too much time checking with the magnet and the blade cooled too much.Also, dull red sounds a little too cool, but color can be very subjective,depending on lighting ,etc. I would not polish it too much before HT. Sand to 320-400 if you like and do the polishing after quench.Heat it up again, and try to get a better soak time and temperature control.Good luck.
Stacy
 
hey all, just completed my project, i neglected to mention that i used a carborizing flame.... so the spot i made was nothing but where i brushed some of the carbon off ! with all the work i did i was worried that i had f&*ked up!
i finished polishing did a mock up of the handle and tempered it in my oven...
i think the handle is rosewood or cherry (i forgot what it was my pop gave me). because the wood was so pretty i just used linseed oil for a finish.those handy little scraps! the edge is a razor! thanks for the help one and all!!! here is some pics---->http://hilarity.zoomshare.com/files/3knife.jpg
 
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