Sherman Armor

I have never heard of Hybrid Sherman Tank Armor (Hybrid M4 Tanks for you Yanks)?

I know obviously by the change in shape of later M4 Tanks with the more angular modern looking design, to me it seemed like a welded Rolled Homogeneous type of armor. I also have seen the rounder earlier M4 Tanks that used a cast design, What I didn't know was produced was a hybrid Armor design which I have never heard of.I know about a lot of Medium M3 and M4 Tanks and Self Propelled Variants, but I have never heard of this type of "Sherman Hybrid Armor" Please explain, Cheers John

The M4 (British Sherman I) and M4A1 Medium (Sherman II) tanks had the welded lower hull of the M3 Medium with a new cast upper hull. The rounded profile of the cast hull makes this model easy to identify.

http://mailer.fsu.edu/~akirk/tanks/GreatBritain/GB-Sherman2A.jpg

The M4A2 (Sherman III), M4A3 (Sherman IV) and M4A4 (Sherman V) of course had the distinctive welded upper hull with squared off edges.

http://mailer.fsu.edu/~akirk/tanks/GreatBritain/GB-Sherman4C.jpg

The late production Sherman I was also built in a composite or "hybrid" form with the radial engine mechanicals and cast front hull of the M4 combined with the welded rear hull of the M4A3. This was known as the Sherman I Hybrid when fitted with the 75mm M3 gun or Sherman IC Hybrid if fitted with the 17-pounder.

http://mailer.fsu.edu/~akirk/tanks/UnitedStates/mediumtanks/usmt-M4A1-late-withcompositehull.jpg

Welding RHA or FHA plate to cast armor from a metalurgical point of view is no problem. The armor will have different properties but technically it is not a problem to do it. The American T20 series medium tank hulls were all a combination of cast (nose and glasis) and welded (hull) armor. Flat plate armor generally has more consistent properties and offers better resistance to penetration for a given thickness than cast armor but cast armor can be formed into better ballistic shapes - the rouned edges of the Sherman hull for example. Pick your poison.

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