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Thread: Panzer tank hull being quenched

  1. #11
    Frank S's Avatar
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    While the weight of the tank frame is significant it is only about 1/4 of the total tanks empty tactical weight. the 4 stubs would most likely be considered expendable then probably removed during the machining process
    The 4 chains would not have been in the furnace with the tank and would only receive heat radiating from the mass
    Visiting a large foundry such as that one would be a great bucket list item. I've been to smaller ones and a couple of steel mills
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    The point I am making is the steel is at red heat. I didn't look it up but steel has probably lost 60%-80% of its tensile strength at that temp. The chains are in direct contact and are getting weaker by the minute. Obviously all accounted for; but someone was watching the clock . . . or the color of the chains!

    BTW, heat is being conducted directly into the chains by the stubs!
    Last edited by Saltfever; 08-01-2017 at 08:30 PM.

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    I know what you are saying about someone watching the clock. or accounting for the amount of time elapsed from initial opening of the oven hooking the chains and dunking the mass in the quenching vat. the watching the clock in this case I imagine would be metaphorically speaking.
    Once as a kid in the blacksmith shop where I worked I picked up a pair of tongs a little to close to the business end I immediately dropped them in the quench tank the Blacksmith asked what's the matter son were they too hot for you?
    Nope it just didn't take me long to look at them.
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    Quote Originally Posted by Frank S View Post
    I was thinking about the shear enormity of the furnace to heat up that much mass probably have to be fed by a 24" or larger gas main maybe several
    there are the furnaces behind the pic

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    Quote Originally Posted by Saltfever View Post
    Interesting! Consider the weight of the whole tank. Then it is being suspended by 4 chains (that are also being heated and weakened!) attached to 4 stubs that have been heated and lost strength. Timing of this operation is non-trivial.
    that is not the whole tank, just the raw casting of the as yet unmachined tub, its still very heavy

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    Sorry, wrong word. Instead of "tank" it should have been "casting". Besides that it doesn't even look like the tank or tub. It appears to be the truck casting which is a part of the overall assembly and likely only a very small part of total assembled tank weight.

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    Jon
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    Can anyone speak to the use of casting to manufacture this tank hull, as opposed to welding or riveting/bolting? Or is this practice simply common for the tank hull, but other processes are combined to manufacture the entire tank? I'm curious about differing strengths, cost, and how different processes may have been used over the years, especially with varying military resources available in peacetime vs. wartime.

    Also, here is a fullsize image version more suitable for offline reproduction:

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    Jon I couldn't say about the Abrams but many of the US tanks and others around the world the hulls and turrets were essentially made from large steel castings many of the other large components were steel forgings. Casting the hull in one piece saves time and money not to mention is makes structurally stronger than mere welding riveting or bolting could ever achieve.
    I imagine that the process of creating a single casting of that size probably required more than one crucible of molten metal then re heating it if the oven and quenching would insure good molecular adhesion and alignment
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    Quote Originally Posted by Frank S View Post
    Jon I couldn't say about the Abrams but many of the US tanks and others around the world the hulls and turrets were essentially made from large steel castings many of the other large components were steel forgings. Casting the hull in one piece saves time and money not to mention is makes structurally stronger than mere welding riveting or bolting could ever achieve.
    I imagine that the process of creating a single casting of that size probably required more than one crucible of molten metal then re heating it if the oven and quenching would insure good molecular adhesion and alignment
    that could not be a forging, it has internal cavities,, its possible many castings welded into a single piece, then heating would normalize stresses, quenching might then harden the hull/tub, that hull is upside down, there are more plates to be welded in,,the square holes showing, one of the holes would be the emergency bottom hatch buck

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    Buck I did not mean to imply that the hull was a forging what I said was there are forgings utilized in the making of tanks. and yes the panzer could have been a welded assembly of welded parts then as you said heated to normalize and harden. The process of doing something like that bringing it to a full red color would be extremely stressing on any welded areas as rolled plate steel has a natural directional grain which cause it to expand in differing directions when heated. One reason for my belief that this is a steel casting is the lack of any fixtures jigs or braces to be seen which would be very prevalent if this were a weldement as such items are never removed prior to heat treating. otherwise the whole assembly could become misshapen to the extent of being scrap metal.
    Whereas a homogeneous casting is grain neutral even when poured by multiple crucibles as long as the plug remained at temperature.
    I was once hired or rather asked do do a favor by the owner of a company that had a contract fabricating transport fixtures for the engines that were used on one of the fighter jets For Lockheed Martian, see if I might have or be able to come up with a solution for their problem. They were experiencing a near 100% NO-GO rating on their fixtures after they returned from heat treatment. the Gov inspector would sign off on the fixture prior to heat treating for fit finish and tolerances . Upon their return he failed every one of them. some measurements would be undersized some over sized some out of dimensional squareness , parallel, angles were off, you name it if there was a possibility to be wrong they would be. then they started sending them in still in fixtures this made an improvement but still not within specs. I started noting the dependencies then I noticed a pattern of the under and over out of square and so forth so once I thought I had most of it figured out I instructed the companies engineers to spec out some new fixtures with built in adjustments plus add in some fixtures in several different places most of those could not be put in place until the weldement was completed.
    After the G man signed off on the assembly to sent it out for treatment we tweaked the jigs here and there by just a little more than the final discrepancies were and added in the extra fixtures. then sent the one frame out to be treated when it returned we removed all of the fixtures prior to final inspection as was SOP
    the frame received an 80% pass which was close enough for the G man to say that it could be ground and reamed and utilized.
    After that first passing grade all of their frames passed even closer to specs by the end of their contract I heard they were obtaining a near perfect pass rating
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