Adam Elsdon Posted January 23, 2009 Share Posted January 23, 2009 I have seen these markings on various armoured vehicles, and have heard various explanations on what they are. On my particular vehicle they are pretty randomly scattered about the armour, and on the top corner of a door, it looks like a manufacturers stamp. Any ideas? Quote Link to comment Share on other sites More sharing options...
Marmite!! Posted January 23, 2009 Share Posted January 23, 2009 I was told by various sources that they are hardness testing marks, they swung a weighted sprung pendulum across the armour and messured how deep the scores were to determine the harndness... of course this could be a load of bollo... Quote Link to comment Share on other sites More sharing options...
Shakey985 Posted January 23, 2009 Share Posted January 23, 2009 The Vickers Medium has similar markings all over the hull and turret. my understanding is that this is done after the plate is heated and rolled to size, in the rolling process the steel grain,molecules are forced in one direction, so when cooling the steel is hammered in at right angles to force the grain to move, flow at that angle giving it extra strength. Quote Link to comment Share on other sites More sharing options...
Adam Elsdon Posted January 23, 2009 Author Share Posted January 23, 2009 (edited) Its quite odd that some of my vehicle has very few marks if any in places and then plastered in others! The numbers in the top corner of the door may also reflect the year it was made, the HLD59 stamp would be from the right era (1959) that the Pig was manufactured. Edited January 23, 2009 by Adam Elsdon Quote Link to comment Share on other sites More sharing options...
Marmite!! Posted January 23, 2009 Share Posted January 23, 2009 My old Ferret has numbers stamped on different bits of armour, probably batch numbers Quote Link to comment Share on other sites More sharing options...
Richard Farrant Posted January 23, 2009 Share Posted January 23, 2009 Its quite odd that some of my vehicle has very few marks if any in places and then plastered in others!The numbers in the top corner of the door may also reflect the year it was made, the HLD59 stamp would be from the right era (1959) that the Pig was manufactured. Adam, I will stick my neck out and say those strike marks are not to test the hardness, but part of the process of straightening precut plates after or during the hardening process. I have noted that those with most strikes are often plates with ports or hatches cut into them, presumably they distort more than plain plates. On Daimler Scout Car hulls, these are often seen as I previously described, also on each plate, can be found a small ground patch, about 1/2" x 3/4" with a neat indentation on it as if a ball bearing had been pressed in to the plate. This is what is known as Brinell hardness test, the Rockwell test was of similar appearance. These tests consisted of a ball of certain size being pressed on to the machined surface with given force. The depth of indentation would give the hardness. The ground or machined surface was critical in order to get an accurate depth measurement. I am going to have a guess, but HLD might indicated the maker of the armour plate, in this case possibly Hadfields, in Sheffield. The Daimlers were usually stamped S&J.....Spear & Jackson. Quote Link to comment Share on other sites More sharing options...
Adam Elsdon Posted January 23, 2009 Author Share Posted January 23, 2009 Richard, that makes sense, there is indeed more marks on the panels that have apertures in them. Good info on the manufacture of the plate!:thumbsup: Quote Link to comment Share on other sites More sharing options...
antarmike Posted January 24, 2009 Share Posted January 24, 2009 (edited) http://www.hmvf.co.uk/forumvb/attachment.php?attachmentid=6815&d=1232733793 AS you say around a hatch or opening Edited January 25, 2009 by antarmike Quote Link to comment Share on other sites More sharing options...
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