Induction heating?

[A.McPherson]

So I've been reading Verhoeven's metallurgy for the non metallurgist book... any reason that induction heading isn't a good way to heat knives for heat treat?

 

[Stacy E. Apelt - Bladesmith]

Cost and the fact that it isn't easy to hold things at an exact temperature for any length of time make it not useful for knife HT. For knife HT a well regulated kiln is the way to go.

Induction heating is wonderful for things where a specific part of the metal needs to be rapidly heated to an approximate range. It is used to harden the teeth on bi-metal band saw blades and such in industry.

 

[Wolf_HR]

The way I understand it, coils are the biggest part of problem, they have to fit rather snugly over the workpiece which would mean that each knife type would need its own custom coil. As Stacy pointed, HF induction is shallow penetrating, and even then is far from uniform- but I think with LF through heating of the knife could be possible... Another issue is that efficiency of induction heating drops significantly past critical point (steel turns non-magnetic), so if needed to go beyond that point, additional heating elements would most likely be neccessary.

 

[mete]

Induction penetration is dependent on frequency --high F , low penetration. Induction is best for production where each piece is the same size and shape.

 

[stezann]

as Mete pointed out, induction heating would be one of the best heat treating methods, but the biggest work would be optimize coils and frequency for the exact part to be treated....then you can do batches.
One of the best methods for the quicker austenitization = finer grain.
All this considered, the best for custom knives remains molten salts.

 

[A.McPherson]

Cool, thanks for the input guys!