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Talk:Rolled homogeneous armour

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Should each word be capitalized in this one? As far as I can tell, rolled homogeous armour is not a proper noun, and should not be capitalized throughout. Joshbaumgartner 17:06, 2004 Nov 17 (UTC)

That quote about the efficacy of RHA seems like it should probably be sourced. --Xanzzibar 08:23, 4 Jun 2005 (UTC)

-Added "unknown source" until the information is apparent. Mushin 19:14, 29 July 2005 (UTC)

"RHA itself is obsolete due to advances in vehicle armor". Who came up with this idea? Most APCs and AFVs are mostly RHA. Dudtz 7/1/06 2:46 PM EST


The nameEdit

What does Rolled in the name of the armor refer to? The only guess I came up with is Rolling mill or Rolling (metalworking). Is this correct? Are thick plates of steel really created through rolling? If this is correct, this article should mention this and link to one of these articles.

Yes, it referrs to the metalworking technique. The actual armor could be made using other techniques, such as casting (armor with complex curves such as tank turrets were sometimes made this way), but rolled steel is used for comparison purposes, since it was the most common way to make large steel plates, and it's a reasonably uniform material. --Carnildo 03:01, 28 August 2006 (UTC)
In particular, it is referring to older armor which was generally very high strength cast steel. The switch to tanks fabricated entirely from high strength rolled alloys was a major post-WW-II improvement, once the alloys were good enough to allow it.
Footnote: in reference to the "expert review desired" tag, I am not an armor professional, but a highly educated amateur. Georgewilliamherbert 05:24, 22 September 2006 (UTC)

"Increasing the protection on a vehicle meant adding thicker sheets of steel, increasing the vehicle's weight and reducing its mobility." - Shaping and sloping armor was as much a factor as simply making it thicker.


I added some links to the particular US military specifications mentioned. This is obviously US-centric, so please feel free to add other specs as desired. Bosef1 (talk) 03:59, 11 October 2011 (UTC)

Rolling ProcessEdit

The article mentions that the steel is hot rolled, to have a homogenous crystalline structure (which makes sense), but in the sentence right after, it says that the rolling also elongates the crystalline structure, which AFAIK only happens if the metal is cold rolled. If someone has more knowledge about that kind of armor, this info should be verified and the wrong sentence removed. " (talk) 04:26, 28 July 2012 (UTC)"

HEAT and APCR roundsEdit

Both HEAT (high explosive anti-tank, a.k.a. hollow charge) and APCR (armor-piercing composite rigid, an early kind of KE round) were developed and used in World War II, as early as 1941/42. Perhaps reword the article a bit so that it doesn't sound as if these rounds were post-war inventions. (The problem just became more and more apparent as the effectiveness of these rounds increased.) -- DevSolar (talk) 14:11, 27 August 2012 (UTC)

False charachterization in 'Specifications'Edit

The article says 'RHA is similar to SAE 4340 steel alloy.[3]', but the linked ref doesn't actually say that.

the question is: 'I see that most of these references are citing an RHA steel - but what designation. Most of the papers (including the one you cited above) refer to J-C parameters that are typical for a 4340 steel. Does this mean that RHA ~ 4340?*

the answer is 'Regarding RHA, it is not the same as SAE 4340. The MIL standard shows the chemical composition for RHA, which has a lower range of carbon than 4340, among other differences. You can find the composition of 4340 on Matweb or other any number of other sites.'

I am uncomfortable using this reference to say that 'RHA is similar to SAE 4340 steel alloy'. How similar is similar when you take away the differences? — Preceding unsigned comment added by (talk) 07:33, 15 October 2016 (UTC)

Saying one type of steel is "similar" to another is a mis-characterization of the physical properties of the material. Just because two types of steel have similar yield, tensile, and elongation, as well as a generally similar base chemical makeup, doesn't mean they are the same.
For example, ASTM A572-50 is a commercial grade of steel not intended for significant mechanical manipulation (bending) of the material. It's nearly identical to ASTM A709-50W, except for some slight chemical differences, and has nearly identical physical properties.[1] However, while A709-50W can be substituted for AAHSTO-M270W steel for building bridges and other water-spanning structures, standard A572-50 would rust away rapidly in the same environment.[2]
SAE 4340 is an automotive grade of steel, with properties set by the Society of Automotive Engineers. It has nothing whatever to do with military specifications for steel armor plate. Suggesting they are similar is very imprecise. NJOpsGuy (talk) 18:32, 16 August 2018 (UTC)NJOpsGuy

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