Aluminum quench medium question

[i4Marc]

Ok, I know aluminum plates can be used to quench some steels. But the plates don't conform well to the shape of the blade, particularly the bevels and any other tapered surfaces. My question is: would an effective alternative to plates be a bucket or other container filled with aluminum BBs or small diameter balls (or even powder)? There would be much better conformation to irregular shapes but would there be enough heat transfer through the medium to make it effective as a quenchant? One of the advantages of plate is the fact that you can clamp it. Would a container filled with tightly packed spheres or powder offer enough resistance to blade warpage?

 

[Frank Niro]

Your question and suggestions bear a lot of interest. I have read where some have special clamping set ups to go with the aluminum plates. I have Rob at Canadian Knifemaker Supply do mine. I believe him to be an expert for the types of stainless steels I want done. A maker friend of mine says the salt pots are the way to go but we haven't talked about how "that way" is the straight way. I hope I'm going to encourage more conversation on this and at least provide me with more back ground. I hope Rob Ridley will step in with some of his experience. Frank

 

[Bill DeShivs]

You need both the mass and the thermal conductivity continuity of solid aluminum, I would think.

 

[sunshadow]

Push a soft blade into a pile of powder and you will bend it

-Page

 

[Stacy E. Apelt - Bladesmith]

Aluminum plates will absorb the heat from a hot blade just fine. The quench speed of aluminum plates compared to air is much greater. We are not trying to imitate Parks #50, just trying to speed up an air quench a tad. The main point of using the aluminum plates is they limit warp during cooling. Cooling speed is a bonus, not the prime feature. The steel would harden just fine without any plates at all.

As to the gap around the bevels, the radiant heat energy crosses those couple hundredths of an inch of air easily.....and remember, it is an air quench we are speeding up in the first place. The aluminum pulls the heat from the air gap and provides more cool air for the quench. A tad slower than metal-to-metal contact, but more than fast enough for cooling stainless steel.

 

[i4Marc]

Ok, great information Stacy. Thanks.