Wikipedia pages often provide useful, well researched information. But sometimes a page contains pure nonsense. Their page for the Tiger I heavy tank claims:
“The armour joints were of high quality, being stepped and welded rather than riveted, and were made of maraging steel.”
If, as you should, you then check by following their link to the page on Maraging steel, you will find it instead says that type of steel originated at the International Nickel Company (Inco) in the late 1950s. It was not around until fifteen years after the end of World War II!
When did the Wikipedia page on that tank first make that mistake? The Wayback Machine shows that on September 28, 2012 the page had added “and were made of maraging steel” – absent from the April 3, 2012 version. In Google searches I was unable to find a reference to back up the claim that maraging steel was used.
But two YouTube videos refer to maraging steel armor: this one and this one. There also is a LinkedIn Pulse article by Henning A. Klovekorn on May 11, 2015 titled The Schwerpunkt Leadership Principle, and a web page from the Hisart Museum in Istanbul.
I searched for what steel actually was used for armor on the Tiger, but could not find specifics. A book from by Thomas L. Jentz and Hilary L. Doyle titled Germany’s Tiger Tanks ends with Appendix D on Armor Specifications. It discusses the Tiger II rather than the Tiger I, and describes the PP793 Krupp specification for rolled armor plate – a medium-carbon low-alloy steel with 0.34% carbon, 0.42% manganese, 0.39% silicon, 2.32% chromium and 0.22% molybdenum. According to the Wikipedia page a Grade 200 maraging steel has no carbon, and nominally 18% nickel, 8.5% cobalt, 3.25% molybdenum, 0.2% titanium, and 0.1% aluminum.
Maraging steels have very different compositions and heat treatment response than the medium-carbon low-alloy steels actually used for tank armor in World War II. When cooled from their high temperature austenite structure both types of steels form martensite. As-cooled low-alloy steels have a very high hardness, and the subsequent tempering heat treatment lowers it by precipitating carbides. As-cooled maraging steels instead have a very low hardness, and the subsequent age-hardening heat treatment raises it by precipitation of intermetallic compounds.
An image of a Tiger I tank came from Wikimedia Commons.
1 comment:
Yes, I have read too where maraging steel was developed in the 1950s. So of course it could not have been used in the tigers. Good work in catching that. But maraging steel seems to have tremendous tensil strength, up to double or even triple that of most rolled homogenous armor, and good elongation, comparable to the 15%+ of armor plate. The aging process can also get it up into the mid 40s or even 50s on the Rockwell hardness C scale. So, I’ve often wondered if it was used as armor. But I suspect the large amounts of expensive alloying elements in it preclude using it at the scale needed in the manufacture of tanks.
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