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Hardening and tempering

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KHalverson:
Also edge geometry comes into play.
U see some guys use a flat Scandinavian grind.
Then it chips chopping cow bones.

DC:

--- Quote from: bubby on April 05, 2018, 10:02:55 am ---The mastersmith does the tempering on all blades. They know what steels they used and watched them forge them, it seems most of the chipping comes from to thin an edge profile most of the time. They also use a even heat oven to treat them and make sure of the temps.

--- End quote ---
I wonder why they chose to do it like that? Maybe because of the wide choice of steels, some contestants may be working something new to them but still, tempering is an integral part of blade making. My suspicious mind makes me think they could steer the outcome that way. I'm not accusing them of that but it's there.

bubby:
It could be because of the mystery steel they use and the fa t that a lot of the Smith's only use known steel that they figure that they know how it should be tempered

jim l.:
It's been my experience that steel type is only one aspect of the heat treat. Granted that certain steels require very specific heat treat regimens. That said, the steel provided to the contestant  is usually hardened by quenching oils (also provided).

Many of the variables come into play such as normalizing, quench temperatures (how hot was the steel - white hot, dull red, yellow) which determine grain structure, and temperature ranges used for thermal mass of the steel. How thick was the blade at each cycle for even thermal saturation. A 1/4 in. thick piece of steel will require more saturation time than a 1/8 in. thick piece. If both pieces are tempered for the same period of time, the thinner piece would probably be softer.

Part of the "trick" in the show is paying attention to the parameters. Many people can hammer out a blade, but will they be able to make it to parameter and stand up to the tests. I:E - "this knife will need an edge profile that will be able to withstand the shock and vibration of hacking a piece of oak 10 x 10 (axe?) but be able to slice through a pork shoulder human analogue (chef's knife?) .

The Smiths have to come up with appropriate edge geometry, cross section, and steel hardness. The tempering I believe is standardized by the Master Smith(s) to accommodate the "ideal" tempering cycle to meet steel provided and parameter requirements.

Besides, the period when the temperature takes place is when they eat lunch.  -C-

Mesophilic:
I can usually tell which knives will fail just based on the color they go into the quench and the blade profile.  Surprises me the credentials of some of the individuals and the simple mistakes they make.  I really don't think I could do better, but have higher expectations of guys who work steel full time.  Maybe it's just that they sre handicapped without their computer controlled Evenheat furnaces.

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