Can I get some kindly advice on hardening and tempering W2 Steel? The info I have says to heat to about 1470 degrees, then quench in water or brine. BUT.....is there a specific or best temperature for the water or brine? I have a 36 inch bar of cold rolled W2, 1"X1/8. The first knife I've made from it is a delicate little jewel,less than 7 inches long. The blade is about 4 inches. At the choil it's about 1/2'" wide and tapers off to a narrow curving tip that that stretches for about an inch or so at 1/4" thickness, ending in a pretty fine point. From guard to tip, the thichness also tapers off, from 1/8" down razor fine. By the beginning of the last inch and a half the thicknes is about 1/16.
I'm not exactly sure just how hard I got this blade. It will probably never be used and just kept in a case by its new owner anyway.
How would you have treated this blade, and what tempering hardness do you thing would have best suited it? Any suggestions for the future blades I make from this stock?
Tanx to all who reply!
i've been making blades out of old Nicholson files (which should be made of W2) for some time now.
Just 4 words: STAY AWAY FROM WATER.
Best, 6 words: STAY THE HELL AWAY FROM WATER.
That's better.
W2 has so much carbon that just moving it around in air will somewhat temper it.
W2 is tempered in water when it has the thickness of your average file.
Do it with a knife-thick blade, and you'l crack it as sure as the sun gets up every morning.
You can use 15W40 motor oil, or 5W30 for a harsher quench. I now use hydraulic oil.
Tempering has to go according to the use. For a knife, with so much carbon in there, you may probably want to go at least to purple for a stubby, solid knife, and well into blue for a long, thin blade that must be able to withstand some flex. For such a blade, I wouldn't use W2 at all, though.
Temper SLOWLY.
The temper is all.
Any dork can get a piece of steel red hot till "da magnet don't stick" and then plunge it in the chosen liquid and "HISSSS make hard".
And get a cristal-brittle blade.
To get a good blade, temper is everything.
A good temper is SLOW. Let the blade heat evenly, and slowly. The color change is only on the surface, and steel is a bad heat conductor. You must let the heat soak in. It takes time. If you rush things, you will get to color too quick, probably go well beyond the intended color, spoiling the hardening of the tip and edge, and keep the spine cristal brittle. A knife with a soft edge and fragile blade, i.e. the opposite you want.
Work slowly. Let the blade reach straw. Keep the edge and tip away from the heat.
There are various ways to do a differential temper that leaves tip and blade hard, while getting the spine soft and flexible.
I for example rest the edge and tip on a firebrick on the side of the coals, and let the heat come up to the spine. The spine will get blue by the time the tip and edge get straw colored, if you do it correctly.
The heat coming from the forge must be gentle, not the roaring inferno you forge or weld in.
This way, you let the heat come up on one side, and watch the color on the other. When the OTHER side gets to the proper color, the whole blade thickness is at the appropriate temp, and wou won't have overheated the side exposed to the coals.
You may also rest the spine on the red coals, but watch for the tip.
A tip slightly softer than the edge is Ok, in my opinion, as it will be stronger, this way.
But not soft as the spine at all.
Another way is to temper uniformly to the required color the whole blade, then dip edge and tip into water and torch the spine with your oxy-gas.
Another way is to get the whole blade to the correct temp, and quench just the tip and edge, but that's tricky.
Another way still is to heat the blade edge down, get to the proper temp just edge and tip and quench the whole blade, and this is even trickier.
Choose the method, or combination of methods, you prefer.
Remember though: W2 is good for short, strong blades which need to be abrasion resistant. A chubby skinner is ideal.
For long, slender blades, such as most fighters and most bowies, you want something like 1075 or, even better, 5160.
. If this is your one venture into the knifemaking game things should be fine, however if you want to make and sell any more, you must rid your mind of such thinking forever. About the time you don't make every one as if it was going to pushed to the limits in front of 10,000 people, the would be collector that was going just display it forever will change his mind, sell it, or pass away (hopefully not, but it will happen eventually), and then a knife with your name on it will the out there facing whatever the next guy can throw at it. 
