Friday, December 8, 2017

Deep Fried Tank


The hull of a Swiss Panzer 68 being treated in an oil bath in the production lines at Thun, Switzerland in 1977.
Text following the procedure from an Oleg Sapunkov:
“The hull would have previously been cast, fettled (cleaned of any sprues/risers/runners/ etc.), and descaled (cleaned of oxide scales on the surface).
The cleaned hull would then be reheated, and kept at high temperature for many hours, to homogenize the metal. Homogenization allows additives and impurities dissolved in the steel alloy to diffuse more uniformly into the grains within the resultant component – since during the cooling of the initial cast, a high fraction of additives is segregated out to the grain boundaries, which weakens the metal. Once the alloy is sufficiently homogenized, the hull is tempered in an oil bath, to decrease its hardness (resistance to permanent deformation under compressive force), but increase its toughness (ability to absorb energy before fracturing).
Finally, following the oil bath tempering, the hull is face-hardened by quenching (rapid cooling). Face hardening produces a metal component with a hard surface, but a tough interior, so that the resultant armor has a higher probability of preventing an incoming projectile from penetrating the hard face (either by deflecting or shattering the projectile), but also will be more difficult to fracture entirely in case the projectile does penetrate the hardened surface.”

9 comments:

  1. Next week on "Forged in Fire"...

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  2. The panzer 68 did have a few minor design problems. Like when you turned on the radio the turret would rotate by itself until you turned it back off. If you turned on the heater the gun would fire the chambered round at random. The NBC system didn't work (at all) and crews would have to use full NBC gear inside the tank, dropping the rate of fire back to muzzleloader speed. Other than that and a few other "minor" problems, they were great.---Ray

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  3. Was that ONE SINGLE CASTING??? Or a fabrication? Either way, that's a big-ass quench bath.

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  4. One single casing.--Ray

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    Replies
    1. I used to be a manufacturing engineer at a steel foundry and ... I'm pretty impressed.

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  5. I'll bet the quenching bath operation after the oil bath was pretty spectacular to see...

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  6. I can't see something like that without thinking how much energy you'd have to throw at it to get it to and maintain that temperature.

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