Art knives and steel hardness?

J

John L

Joined
Oct 28, 2004
Messages
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I see many "art" knives being made with heat blued damascus blades...which I think can be achieved at approx 600-900 degrees F. Most are common high carbon steel and nickel or some sort. Heat treat must be 1450-1500 =/- and tempered at 400-475 =/-. How then do they heat color at 6-900 degrees? without affecting hardness? Or they don't care ... or what? Perhaps I don't get it.
 
How many of these "art knives" do you think actually ever see any use?

A blade that is blue has been heat coored at 600 deg, making it a spring temper. While the edge holding ability can be affected it is probally not terrible. But like I said, who uses these art knives?
 
I have always wondered the same. I suppose I would rather have a pretty knive with a bad temper than a pretty wife with a bad temper...

;)
 
jhiggins said:
I have always wondered the same. I suppose I would rather have a pretty knive with a bad temper than a pretty wife with a bad temper...

;)
Click to expand...


Huh?!?!?;)

I remember back in the 80's there was a big stink about art knives, in that many were found not to be sharpened or even tempered.

Personally, I don't consider it a knife if it doesn't have an edge, or is untempered, just a fancy tent stake. But then, what do I know.:D
 
jhiggins said:
I have always wondered the same. I suppose I would rather have a pretty knive with a bad temper than a pretty wife with a bad temper...

;)
Click to expand...

If I had a pretty wife I wouldn't care about the temper.....for the first couple of years anyway.

(I'm just kidding, my wife reads this forum more than I do, Hi sweetie!!:o :D :p )
 
Robert, are you being courageous or foolish? I hope your sweet wife goes gently on you! ---Sandy---
 
If a person was to take a blade, once grinding was finished, and put it in an oven at the prescribed temperature i.e. 600-900°F and it turnes blue and looks pretty, he (or she if you are politically correct) could then, using a controlled atmosphere heat treating oven run the blade up to austenizing temperature and quench. Sounds like a hard blue blade to me!

Jim A.
 
How does one keep the blade in the controlled atmosphere during the quench?
I'm not sure you can leave it in the oven, then rapidly quench in the oven...:confused:
 
My understanding is the blade is in a box inside the oven. The box is conected to a nitrogen or argon line. Once the blade is austenized and soaked, the oven is opened to cool the exterior of the box and the gas flow is increased to what ever flow rate is needed to cool the blade fast enough to clear the P nose. I believe this is mentioned in the Machineries Handbook.

Jim A.
 
Just make sure your woman can cook. Then its easier to ignore the temper. :D
 
Cooking your blade for a longer time at the same temp will not get you more colors. If I left a blade tempering in my oven at 400 deg for 2 hrs compared to 5 hrs it will still be at the same temp and have the same straw color.

Low temp salts will get you a blue/black color but that's it! These salts are also much more caustic and hazardous than nitre bluing salts.

Nitre bluing salts can get you a range of colors based on temperature from straw/bronze, purple and then blue. You can even color damasteel with them.
They are safer and do not require an iron pot, basket ect for use.
 
the colours are a result of an oxide layer beeing formed on the surface of the steel. the thicker the layer the darker the colour. (its roughly the same with titanium)
the thickness is a result of energy, time and oxygen. assuming there is endless oxygen the colour can be adjusted by changing the temperature (=> more energy) or the time .

have you ever tried it, or do you simply know it wont happen :)

edit to enter this pdf (http://www.rubig.com/haertetechnik/downloads/Praxissevice.pdf)
on page 32 is a chart showing the tempering-temp in °C (=> °C*2 =°F) and the tempering-time)
 
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