Tempering a Swiss sword

Via the Tank Museum

One of the most magnificent images of a tank in production – a glowing hot Swiss Army Panzer 68 hull being heat treated in an oil bath, at an Eidgenoessische Konstruktionswerkstaette facility in Thun, Switzerland, 1977. 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. (Text credit Oleg Sapunkov)

The finished product:

Preserved Swiss Army Panzer 68 at Hinterrhein

Some 390 Panzer 68s were made in the 1970s and remained in service with the Swiss until they were replaced by the new Panzer 87 (license-built Leopard 2) in 2003.

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About laststandonzombieisland

Let me introduce myself. I am a bit of a conflict junkie. I am fascinated by war and warfare, assassination, personal protection and weaponry ranging from spud guns and flame throwers to thermonuclear bombs and Soviet-trained Ebola monkeys. In short, if it’s violent or a tool to create violence it is kind of my thing. I have written a few thousand articles on the dry encyclopedia side for such websites as Guns.com, University of Guns, Outdoor Hub, Tac-44, History Times, Big Game Hunter, Glock Forum, Firearms Talk.com, and Combat Forums; as well as for print publications like England Expects, and Strike First Strike Fast. Several magazines such as Sea Classics, Military Historian and Collector, Mississippi Sportsman and Warship International have carried my pieces. Additionally I am on staff as a naval consultant and writer for Eye Spy Intelligence Magazine. Currently I am working on several book projects including an alternative history novel about the US-German War of 1916, and a biography of Southern gadfly and soldier of fortune Bennett Doty. My first novel, about the coming zombie apocalypse was released in 2012 by Necro Publications and can be found at Amazon.com as was the prequel, Chimera-44. I am currently working on book two of that series: "Pirates of the Zombie Coast." In my day job I am a contractor for the U.S. federal government in what could best be described as the ‘Force Protection’ field. In this I am an NRA-certified firearms, and less-than-lethal combat instructor.

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