draganm Posted January 30, 2016 Share Posted January 30, 2016 Being a machinist, welder, and metal worker One thing I've been curious about is WW2 tank armor. Some quick research shows that the general rolled homogeneous Armor (RHA) is roughly equivalent to today's 4XXX series of molybdenum steels, approx. 4340 or thereabouts. I can see they vary the percentages of silicon or nickel or whatever by a few tenths of a percentage point depending on thickness, application, etc. So my question is when these guys are restoring lets say a Panther or some other tank with really thick plate where there's a huge hole blown thru it, what's the general approach here? Do they 1) replace the entire piece with the same thickness and alloy plate? this would appear really unlikely as simply finding a chunk of specialty steel that's 6 feet square and 3 inches thick would seem unlikely 2) patch the hole with a thinner piece of metal , using a common grade of low carbon steel and a filler rod designed for fusing dissimilar metals 3) find a donor vehicle and cut parts off it, but with something super rare where every chassis is worth a mint, doesn't seem viable 4) replace the entire piece with a large chunk of thinner low carbon steel. Seems like this would make fitting the drivers visor and bow gun difficult as they're designed for a much thicker plate? However I do believe the Littlefield/Collins Panther turret, which was a full re-pop and maybe used mild steel that was water jet or plasma cut and then welded together based on a CAD model one of their tech guys created. So how exactly would you restore this ? Quote Link to comment Share on other sites More sharing options...
Adrian Barrell Posted January 30, 2016 Share Posted January 30, 2016 If that's the vehicle I think it is, it has a new glacis plate ready to be welded in. I always use mild steel of a matching thickness to replace or repair. Quote Link to comment Share on other sites More sharing options...
eddy8men Posted January 30, 2016 Share Posted January 30, 2016 i always try to keep as much of the original as possible and patch with original armour plate (if available) failing that just use mild steel. the turret roof of my cromwell was badly dented from an arty round and we ended up cutting the damaged section out and fitting mild plate instead, the work was done at bob's yard by a freind and looks original. Quote Link to comment Share on other sites More sharing options...
draganm Posted January 30, 2016 Author Share Posted January 30, 2016 do you recall what you used or what was readily available, cold rolled 1018 or hot rolled A36? Or did you custom order foundry plate? the scaling on the hot roll would make for much increased prep time no? Quote Link to comment Share on other sites More sharing options...
eddy8men Posted January 30, 2016 Share Posted January 30, 2016 didn't get into the steel specs as it doesn't matter as long as no one is shooting at you, just normal mild steel plate is perfect, prep time along the weld seam isn't enough to worry about. just turn the amps up and go for it. make no mistake though i am no master fabricator, just a guy that likes tanks. so don't take my word as gospel but it isn't rocket science either and when these things were put together in the factory 70 years ago they didn't do every weld perfectly ! Quote Link to comment Share on other sites More sharing options...
draganm Posted January 30, 2016 Author Share Posted January 30, 2016 (edited) didn't get into the steel specs as it doesn't matter as long as no one is shooting at you, just normal mild steel plate is perfect, prep time along the weld seam isn't enough to worry about. just turn the amps up and go for it. well I can believe that, I do mostly stainless and AL, and most of it has to be gas/water tight, so ultra clean welds are the rule. For Structural welding on steel however I don't think is very important short of really greasy or extremely scaly stuff. i always try to keep as much of the original as possible and patch with original armour plate (if available) failing that just use mild steel. the turret roof of my cromwell was badly dented from an arty round and we ended up cutting the damaged section out and fitting mild plate instead, the work was done at bob's yard by a friend and looks original. if it's war time damage, versus target range hits, isn't the conventional wisdom to leave it be? just curious so don't take my word as gospel but it isn't rocket science either and when these things were put together in the factory 70 years ago they didn't do every weld perfectly !makes sense, the life expectancy for a WW2 tank was what, 2 weeks? It wasn't headed to a car show Edited January 30, 2016 by draganm Quote Link to comment Share on other sites More sharing options...
Big Al Posted February 1, 2016 Share Posted February 1, 2016 One trick we have used with mild steel is leave it out side for a year so it gets a pitted surface then cut and weld into place. It dos not show up to much when its finished. Al Quote Link to comment Share on other sites More sharing options...
eddy8men Posted February 1, 2016 Share Posted February 1, 2016 "if it's war time damage, versus target range hits, isn't the conventional wisdom to leave it be? just curious" i have left some damage on the cromwell turret but it is only from it's time as a range target, which is when the roof was damaged. i often hear people at shows commenting on the splash marks on the turret. my carrier has had 3 armour peircing rounds through the side and i chose to leave the holes in as part of it's history. Quote Link to comment Share on other sites More sharing options...
Big Al Posted February 2, 2016 Share Posted February 2, 2016 "if it's war time damage, versus target range hits, isn't the conventional wisdom to leave it be? just curious" i have left some damage on the cromwell turret but it is only from it's time as a range target, which is when the roof was damaged. i often hear people at shows commenting on the splash marks on the turret. my carrier has had 3 armour peircing rounds through the side and i chose to leave the holes in as part of it's history. Yes Rick its part of its history and a good talking point for the public on Johns valentine we left the welded joints when he rebuilt the turret from when it was cut up . Al Quote Link to comment Share on other sites More sharing options...
eddy8men Posted February 2, 2016 Share Posted February 2, 2016 lol you rarely run out of people who want to talk to you at shows, i still have a laugh about someone calling john's valentine a hovercraft Quote Link to comment Share on other sites More sharing options...
Lauren Child Posted February 3, 2016 Share Posted February 3, 2016 I'm not a welder (though I hope to learn), but there is some probably useful advice on welding different types of armour in a pamphlet called "Notes on welding technique part II; The repair of armour plate in the field" from October 1943. No subsitute for the experience that these folks have, but if you're starting out I can recommend picking a copy up. They show up on ebay/abebooks semi-regularly and there's a copy in the IWM library. If you get stuck I can run my copy through the photocopier. Quote Link to comment Share on other sites More sharing options...
Big Al Posted February 4, 2016 Share Posted February 4, 2016 lol you rarely run out of people who want to talk to you at shows, i still have a laugh about someone calling john's valentine a hovercraft Yes and the one who said why don't you cut the screen off and have a real tank ! Al Quote Link to comment Share on other sites More sharing options...
eddy8men Posted February 4, 2016 Share Posted February 4, 2016 god bless em all lauren that sounds like an interesting booklet, any chance you could take a pic or two of the most relevant pages and post them up on this thread for the good and benefit of the great unwashed. cheers Quote Link to comment Share on other sites More sharing options...
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