A question was raised some time ago concerning the degradation of german armor quality over time. A few even went so far as to say that this degradation was an assumption on the part of some, or presumed, and wasn't based on anything factual.
That is not in fact the case. The US - along with the UK - conducted periodic metallurgical testing of German, Italian and Japanese armor coupons throughout the war. A section of armor plate was flame cut from a captured vehicle (always a non-burner or flamer as this affects the testing), and in the case of the US was shipped to Watertown Arsenal or other US testing facilities.
For those interested in this question you can use the DTIC document library to order the various testing reports. If you want Tiger info try WAL 710/542 - Armor and Welding on a Pz VI Tiger Tank...for example...or WAL 710/608 - Armor and welding on a Pz-IV etc. All these documents are now public domain, and thus its easy to follow the metallurgical trail so to speak.
Over the course of 1944, with most fingers pointing to early in same, the Germans changed the alloy composition of their armor. Prior to this time the usual Cr-Mo type steel was used. All testing showed the plates to be sufficiently cross-rolled and both fracture and Charpy tests showed good fracture and shatter characteristics.
By the beginning of 1944 things changed. Mo was dropped and the plates started their trend to .5% carbon, 2% Chromium, and .14% Vanadium composition. Obviously Mo was running short or had disappeared, and a substitute had to be found that was generally acceptable...and that substitute was the move to vanadium.
This had a couple of effects...first high carbon is generally counter-indicated when it comes to obtaining good welds and shock/shatter performance. The deterioration of weld performance was witnessed in combat by both the German tank crews themselves and the Allies, and became a consistent feature in German armor samples from that point on. Good RHA in the US or UK typically is no higher than .3% carbon at worst. Poor quality steel such as was found in some of the Italian AFV ran as high as .5-.6% carbon, and that of course yields generally horrid shatter performance. Instead of clean penetrations typical of 'good' armor you see large tears in a plate with considerably more material/spall forced into the AFV.
Another issue with this composition is quench cracking...if you dont quench the plate properly in manufacturing you can generate cracks that are inside the plate and invisible to the naked eye. Armor with interior cracking or non-uniform composition is obviously a bad thing when you hit it with a high velocity projectile.
Then, and this is especially true of plates greater than 2" in thickness, the same mad rush to satisfy quantity (thus screwing up your quench cycle) can also affect the quality of the plate. In case of a vandium based steel, you will use less alloy to make it for a given weight, but between that and improper quenching you end up with steel of inferior hardness.
Finally we top all that off with improper tempering...and you actually induce brittleness into what is already a faulty plate. The faulty tempering occured in one of two fashions...either the plate was allowed to cool too slowly or the temperature ranged in the 400-1000 degree F range and didn't exceed that. (Ideally you want 1200-1700 degrees followed by an appropriate quench) A further side effect of this is variable hardness in a plate of a given thickness...and again this was noted in the Panther's armor.
The Panther glacis armor sampled in 1944 demonstrated all these characteristics, and more. Its not that the design of the plate or the weld was bad, it was simply that Germany was out of alloys required for good steel production, and the substitute process adopted was inferior in every way to the material it was replacing. When you throw bad manufacturing process on top of that (improper quench and temper) in hurry to get the vehicle out the door, you get what was seen in combat...brittle and shatter failures in plates which shouldnt have those issues.
When we come off the glacis and to the side armor with much less thickness, its all a formula for outright disaster. In the case of some Panther Chassis, 75mm Sherman HE not only cracked the armor, but literally blew sections of armor plate off the tank...and obviously that should never happen on anyone's vehicle if the armor is up to snuff. I'm sure US officials were surprised to see such a large drop in quality...and they certainly noted in their reports that they believed Germany was (materially) approaching the end of the line.
Other nations had their issues as well...early war matildas for one had issues with castings with regards to both metallurgy and process control early on. These were often a function of a single manufacturer and the controls in place at that location.
So - there you have it. The reduction in armor quality was a product of nothing more than facts. A lack of appropriate alloys and a lack of attention in materials manufacturing...all of which made for brittle and shatter prone tanks and welds.
Could Germany have avoided this fate? Yes...if they had more invested in quality control checks, re-quenching and re-tempering the armor would have eliminated some of these faults. That too was demonstrated in US testing. The barbarians were already at the gates though...and I am quite sure some of the T-34s rushed off the line early on would have similar problems. Heck some of the JS series tanks late in the war had severe quality issues...something which should have never happened given the strategic situation by that time.
I hope this puts this particular myth to rest once and for all. Anyone interested in a late war panther sampling can order ADA 954940 or 954952 for ord. dept comments as well as the full metallurgical workups of a typical late model panther. No use taking my word for it...let the spectroscopy and microscopes in the reports do the speaking...
This was by a player on WWIIOL who goes by the name Scotsman, he is quite knowledgeable and always posts pretty interesting stuff.
His sources he used was:
- WAL 710/542 - Armor and Welding on a Pz VI Tiger Tank
- WAL 710/608 - Armor and welding on a Pz-IV etc.
- ADA 954952 - Metallurgical examination of 3.25" thick armor from a german Panther tank
- ADA 954940 - Metallurigical exmaination of armor and weleded joints from the side of a panther tank.
Thought I would add some pictures of the faulty armor:
Panther A series:
In this first image I saw two things of interest...first is the bow penetration. Its ragged and definately appears overcaliber in its characteristics...an indication of overmatch. Of course panther glacis penetrations fly in the face of the commonly accepted norm that the panther glacis was well nigh invulnerable at normal ETO ranges.
Possibly Panther G series (Possible chin to mantle in picture, which would indicate a G series, I could be wrong)
In this second shot we again see symptoms of below standard armor - with a massive weld failure and tearing away of primary armor from the upper deck as well. No idea what impacted this vehicle...and in fact there might be instances against really large rounds where I could in fact stretch existing armor penetration methodologies to come up with plate failure that would indicate something somewhat smaller than seen in image one.The failure of the upper deck is a good indicator, however, of a bad weld and below average armor quality.