In the early years of WWII, many of the tanks appeared to have armor which consisted of plates of steel, rivetted together. Later, the newer tanks used cast armor or welded plates.
My question: when an enemy shell hit a rivet head, would the momentum cause the rivet to enter the tank? It must have been quite dangerous to have rivet fragments flying around inside…
Yes it would. It was an example of “spalling” and was quite dangerous to the crew. That’s why they switched to welded armor.
Also, incoming fire did not have to hit the rivet directly. Hits anywhere on the armor plate could and did send rivets at the edges of the plate flying.
Unforgivable, since the first turret in combat had the same problem. They’d had plenty of time to learn better.
WWI tank crews sometimes wore chainmail masks to protect from spalls/rivets bouncing around inside the tanks.
There’s an example on the Wikipedia entry here:
They call anything spalled off armor (or bits of the impacting shell) “splinters” in warship fights.
On larger ships, they even would have a second layer of (thinner) armor behind the main belt to catch these before they got even further into the ship.
I believe the issue was that welding techniques were not up to holding a tank together until the late 30’s.
I’ve read descriptions that some tanks were vulnerable to heavy machine gun fire because of this. Even though the MG could not penetrate the armor outright, it could send the rivets flying.
And/or there was an insufficient number of skilled welders in the US at the start of the war. Once the factories had increased their available welder pool, they could really start kicking out all-welded designs.
In WWI, British tank crewmen sometimes wore helmets with a chain-mail “veil” covering the face, to protect against flying rivet heads. Doesn’t seem to have been used in WWII, so the disadvantages must have outweighed the advantages.
It proved visually disorientating, even inducing nausea. Right idea, but it had to wait ninety years for the technology to catch up with it.
Not sure I buy that. I’ve read that the German warships in WWII, which were planned in the 1930s, were designed with superior “electrically welded” hull compartmentation that made them much stronger. Surely if that can be done for a something as large as a warship, it could be done for a tank. Unless this technology was a state secret, which might be the case for all I know, the Allies could have picked it up and used it for their own vehicles.
Given the general state of pre-war design, in which many weapon systems were (it is now known) badly designed*, I’m inclined to think this was more an institutional failure than a technological impossibility.
*See the American Mark 14 torpedo for perhaps the clearest example
The tank had no commercial equivalent (unlike ships and planes where the same competence in the basic technology is needed to make it float or fly). Certainly the British automobile industry had no experience in building heavy commercial vehicles, partly due to the well-developed railway network that made them unnecessary, and the heavy rates of tax that such vehicles attracted (again due to the lobbying of the railway industry).
Whoops, should have read the thread more closely. I guess I don’t have anything new to contribute after all. 
Actually, electrically welded hulls were used on the USA “Liberty Ships”-which were turned out in vast numbers. Many of these ships experienced catastrophic hull failures (the welds cracked).
It turns out that a rivetted ship had more “give” and could take the pounding of the sea better.
The Bismarck suffered a hull failure as well, as did the TURPITZ (sunk in a Norwegian fjord).
AS for cast armor, the Frecnch used it in their heavy tanks-it was quite good, and no tank that the Germans had in 1940, could destroy a Char-B French tank (the only way they could be destroyed was via a direct hit to the side engine radiator vent).
Can you cite that? I understood the Liberty ships to be a largely successful design.
Bismarck and Tirpitz suffered their hull failures for reasons unrelated to construction.
Actually, many of the Liberty Ships did have problems with their welded hulls. For information on one very spectacular example, Goggle on “Flying Enterprise”, a ship that sank amidst worldwide publicity just after the War.
That is not according to my understanding. Liberty Ships had catastrophic failures on account of NDT – nil ductility temperature. Much of the steel used became like glass when it went down to arctic temperatures. The ships broke and sank so quickly, there wasn’t even time to launch lifeboats. (“The Silent War”)