"Hetzer" (Jagdpanzer 38) Armor Quality, allegedly 50% the value of RHA?

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ThatZenoGuy
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"Hetzer" (Jagdpanzer 38) Armor Quality, allegedly 50% the value of RHA?

Post by ThatZenoGuy » 22 Feb 2021 16:49

https://www.youtube.com/watch?v=TzoCGSBpdCs&lc

According to this video the "Hetzer" was built of materials that were equal to 50% the effectiveness of traditional WW2 RHA.

That is to say the 60mm of frontal armor with a line of sight thickness of 120mm was only equal to 60mm line of sight thickness. About as strong as a mid war Panzer 4, and weaker than the latewar panzer 4's.

The source used was Doyle, who alleges this in this video around 18 minutes into it...
https://www.youtube.com/watch?t=1065&v= ... e=youtu.be

He states it used "Siemens–Martin" (What is this?) armor, that was allegedly used in WW1. Although even then an effectiveness of 50% is questionable as that roughly equals the strength of mild steel, something even WW1 tech could surpass.

Now Doyle's Panzer tracts states the side and rear armor was not of great quality, understandable as the tank was very late war, and designed to be cheap. In any case 20mm of high grade steel would be penetrated by almost anything, and 20mm of weaker steel would stop rifle rounds.

But the front was designed to take a hit from peer cannons, and 60mm effective armor just would not cut it latewar.

As I understand it, some sources state the front armor was of "E22" steel specifications, the exact which specifications I do not know, but I've read it was used on the Panther, which was regarded as being "Average quality RHA" on a good day.

So what exactly is going on? Who is right here? And is Tank Encyclopedia being wrong in their claim that the front armor was effectively made of industrial grade steel?

critical mass
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Re: "Hetzer" (Jagdpanzer 38) Armor Quality, allegedly 50% the value of RHA?

Post by critical mass » 22 Feb 2021 16:56

Without providing evidence, it rests on the level of an unsubstantiated claim.

All armor made in Germany was made either electroresmelted or Siemens Martin open hearth with Duplex process, not used by the UK.
Last edited by critical mass on 22 Feb 2021 16:58, edited 1 time in total.

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Re: "Hetzer" (Jagdpanzer 38) Armor Quality, allegedly 50% the value of RHA?

Post by ThatZenoGuy » 22 Feb 2021 16:57

critical mass wrote:
22 Feb 2021 16:56
Without providing evidence, it rests on the level of an unsubstantiated claim.
On the part of Doyle/Tank Encyclopedia?

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Re: "Hetzer" (Jagdpanzer 38) Armor Quality, allegedly 50% the value of RHA?

Post by critical mass » 22 Feb 2021 16:58

Yes.

Sharp reductions of Quality may occur if the armor was defect by temper embrittlement AND if this was not realized and rejected by QC AND such defective plate found its way to AFV. It can happen in a long run of armor lots a couple of times, but this doesn’t justify the statement that the armor was 50% inferior to RHA.

But no evidence was produced and the specifications for E & EM steels do not support his statement.
Last edited by critical mass on 22 Feb 2021 17:04, edited 1 time in total.

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Re: "Hetzer" (Jagdpanzer 38) Armor Quality, allegedly 50% the value of RHA?

Post by ThatZenoGuy » 22 Feb 2021 17:00

critical mass wrote:
22 Feb 2021 16:58
Yes.
Doyle has access to old archives/documents as far as I am aware of, although I don't believe he has ever actually displayed anything that matches his claim that the material was of "SM" steel.

Strangely enough "SM" steel doesn't appear to actually exist, "Siemens–Martin" appears to be a method of producing steel, and has little to do with the strength of said steels.

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Re: "Hetzer" (Jagdpanzer 38) Armor Quality, allegedly 50% the value of RHA?

Post by critical mass » 22 Feb 2021 17:06

EVERYBODY used Siemens Martin steel. The UK, US and SU alike... it has little to do with ballistic resistance.

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Re: "Hetzer" (Jagdpanzer 38) Armor Quality, allegedly 50% the value of RHA?

Post by ThatZenoGuy » 22 Feb 2021 17:09

critical mass wrote:
22 Feb 2021 17:06
EVERYBODY used Siemens Martin steel. The UK, US and SU alike... it has little to do with ballistic resistance.
Any guesses why he brings up SM steel? The guy has seen the few documents relevant to the E-Series tanks, comically rare. And he gets such a simple thing wrong?

Basically that means his claims that the sides were made of "SM steel" are incorrect, although technically correct at the same time. I wonder what specific alloy they used. I have heard from other sources that the sides were not of great quality, then again they could be parroting him.

You have any sources detailing the armor type/grade on the Hetzer?

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Re: "Hetzer" (Jagdpanzer 38) Armor Quality, allegedly 50% the value of RHA?

Post by critical mass » 22 Feb 2021 17:24

SM steel is good quality steel because of the duplex process employed whenever making armor plate. Even without the more refined duplex process, You could generate good steel quality with acid or basic open hearth furnaces if You are willing to use more chromium and nickel. Electric steel was, of course the best, but Duplex rates almost as good as electro steel.

I quote from British post ww2 assessment of German Armor (SUPP-22-58 CHARACKTERISTICS OF GERMAN ARMOUR, originall classified SECRET):
SECTION II Furnaces and production
(...) It is now known that all the thirteen firms engaged in making armour plate used electric furnace steel, that seven of them used exclusively electric steel, and that six firms which used open hearth steel for part of their thicker plate production after June, 1943, made this steel by a duplex process with high quality charges in Siemens Martin furnaces, which lead to a product which could hardly be distinguished by analysis from the electric furnace steel. At least 80 per cent of their armour was made from electric furnace steel and the remainder was high quality open hearth steel made by a process not used in this country. The German armour was, therefore, of more uniform quality than British steel, which, as far as rolled was concerned, was made only to a small extent in electric furnaces, while the remainder was made in about equal proportions in acid and basic open hearth furnaces using the ordinary process."
-Which is the exact opposite to Mr. Doyles claim of wildly varying RHA quality due to the Siemens Martin open hearth process, which he implies resulted in inferior quality. This is a primary source, not hearsay.
Last edited by critical mass on 22 Feb 2021 17:28, edited 1 time in total.

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Re: "Hetzer" (Jagdpanzer 38) Armor Quality, allegedly 50% the value of RHA?

Post by ThatZenoGuy » 22 Feb 2021 17:27

critical mass wrote:
22 Feb 2021 17:24
I quote from British post ww2 assessment of German Armor (SUPP-22-58 CHARACKTERISTICS OF GERMAN ARMOUR, originall classified SECRET):
SECTION II Furnaces and production
(...) It is now known that all the thirteen firms engaged in making armour plate used electric furnace steel, that seven of them used exclusively electric steel, and that six firms which used open hearth steel for part of their thicker plate production after June, 1943, made this steel by a duplex process with high quality charges in Siemens Martin furnaces, which lead to a product which could hardly be distinguished by analysis from the electric furnace steel. At least 80 per cent of their armour was made from electric furnace steel and the remainder was high quality open hearth steel made by a process not used in this country. The German armour was, therefore, of more uniform quality than British steel, which, as far as rolled was concerned, was made only to a small extent in electric furnaces, while the remainder was made in about equal proportions in acid and basic open hearth furnaces using the ordinary process."
-Which is the exact opposite to his claim of wildly varying RHA quality due to the Siemens Martin open hearth process.
enough said.
Technically this would not exclude lower grade steels being made using these processes, mild steels, construction steel, high tensile (but not armor grade), etc.

Although as foolish as Germany could be in places, I hardly believe they'd strap a bunch of saucepan steel onto their tanks for armor unless they literally had nothing else.

Interesting to see that German steel was more uniform in quality though, I have heard that latewar the quality could dip, but mostly because of material shortages.

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Re: "Hetzer" (Jagdpanzer 38) Armor Quality, allegedly 50% the value of RHA?

Post by critical mass » 22 Feb 2021 17:31

Miles Krogfuss has already published the specifications for late war steels in another thread. I couldn´t observe inferior quality. Some of it was less hard in medium section thicknesses, such as employed in HETZER glacis but I´d regard this as an advantage as it facilitates ricochet in highly oblique impact (such as against highly sloped armor plate), which is also reflected by a detailed look into the ballistic acceptance specifications. This was a very good application of metallurgical knowledge.
Last edited by critical mass on 22 Feb 2021 17:32, edited 1 time in total.

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Re: "Hetzer" (Jagdpanzer 38) Armor Quality, allegedly 50% the value of RHA?

Post by ThatZenoGuy » 22 Feb 2021 17:32

critical mass wrote:
22 Feb 2021 17:31
Miles Krogfuss has already published the specifications for late war steels in another thread. I couldn´t observe inferior quality. Some of it was less hard in medium section thicknesses, such as employed in HETZER glacis but I´d regard this as an advantage as it facilitates ricochet, which is also reflected by ballistic acceptance specifications. This was a good application of metallurgical knowledge.
Can you link me these please! ;D

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Re: "Hetzer" (Jagdpanzer 38) Armor Quality, allegedly 50% the value of RHA?

Post by critical mass » 22 Feb 2021 17:41


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Re: "Hetzer" (Jagdpanzer 38) Armor Quality, allegedly 50% the value of RHA?

Post by ThatZenoGuy » 22 Feb 2021 17:46

Curious that it seems latewar German steel was still of 'good' quality.

I'm pondering if that's on a good day with a good plate, while some might go by with some defects. The famous 'glass armor' pictures of Panthers and such.

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Re: "Hetzer" (Jagdpanzer 38) Armor Quality, allegedly 50% the value of RHA?

Post by ThatZenoGuy » 22 Feb 2021 17:56

Amusingly Tank Encyclopedia isn't classifying any of this as a 'source' worth listening to.

Any idea what would persuade them? They insist Doyle's word is gospel.

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Re: "Hetzer" (Jagdpanzer 38) Armor Quality, allegedly 50% the value of RHA?

Post by critical mass » 22 Feb 2021 18:51

ThatZenoGuy wrote:
22 Feb 2021 17:46
I'm pondering if that's on a good day with a good plate, while some might go by with some defects. The famous 'glass armor' pictures of Panthers and such.
Sort of. If You count the impacts in glacis photos (my own database, which is very incomplete) lists 121 events, You will notice ductile failure mode, either by holing or by ricochetting off, is the most prominent failure type. This doesn´t mean brittle events did not occur. They sometimes show drastic plate failure forms with cracks extending all the way from the impact to the next free edge, where they may even dislodge parts of the plate. Its rare but this has been blown out of proportion by selective imagery and has been cast as a dominant failure type, which is an incorrect characterization of the data.
Of course, a less careful observer will just look at the holes and shape of the plate without judging the penetrator. Unfortunately, this will lead to extremely misleading assessments because the cross correlations between armor plate and projectile are expressions of complex dependencies. An intact penetrator will generally leave small, calibre sized holes, either by ductile deformation or adiabatic plugging. A broken up penetrator may leave holes many times the projectile calibre from brittle discing or plugging. If the projectile breaks up, the plate can´t just have a calibre sized, ductile hole formation event as a result of the impact if it fails, unless the breakage occurred AFTER penetration. Its physically not possible because the penetrator is spread out over a larger contact area.
German armor hardness was treated intentionally close to the 1st ductile /brittle transition point against robust penetrators like their own Pzgr.39 series capped AP in order to extract slightly higher ballistic resistence. This treatment in combination with the very lean alloy mix of armor, particularely in thinner sections required very complex thermo-mechanical heat treatments, forced cooling and tempering cycles, often timed to the next 5 seconds to provide acceptable ductility and ideal (but not too high) hardness.
The German armor firms understood fully the effects of temper embrittlement, which was plaguing all combatants to various degrees. The understanding improved towards the end of ww2 but excess reliance on avoidence of temper brittleness was carried out by the british and US in particular, which otherwise made good armor despite the less clean steels cast by acid or basic open hearth furnaces. The soviets, at least early in the war used Siemens Martin open hearth with the duplex process and relatively rich alloyed steels particularely for their medium hard RHA variants, which provided for very good quality armor, particularely in thick sections for the KV-series (it was very difficult by then to make good quality and thick RHA). The switch to high hardness steels, both for RHA and cast (T34 and IS) allowed to forego any complex tempering treatment and thus reduced the effort required to produce armor. This sort of armor was also excellent against inferior AP-quality (acting like face hardened armor against it) and had relatively good ductility if the embrittling tempering temperature range was fully avoided. It only became apparent late that this armor was inferior against the virtually indestructable Pzgr.39 series AP and the armor was switched back to medium hard armor post ww2 (the Czech changed armor on their licensee T34/85 from HHA to medium RHA, which was a vast ballistic improvement as everybody by then introduced improved quality full calibre AP projectiles and the sloped armor plate suffered badly from beeing HHA, failing generally by lower energy adiabatic shear events).

When a 50mm BRUMMBÄR plate were trialed the british, they noted that the resistence was very good but the plate failed with intemediate ductile-brittle failures, such as plugging / discing and the armor was showed to have less Izod impact strength than was specified for british 2" plate. Expecting to be able to improve the armor, they then cut half of the plate and sent it to a firm for reheat-treatment along british practices and the impact strength as a consequence improved drastically. They noticed then that the armor was now much better and would have passed the british specifications with flying colours. Yet, compared with the original plate, the limit velocity against penetration and perforation was lower, not higher, and they were perplexed by how the ballistic resistence of the plate was REDUCED by this treatment, which improved metal properties. German armor intended to obtain increased ballistic resistence but by doing this, they may have obtained armor which was of high quality resistence against plastic deformation from attack by high quality projectiles with good but not excessive capacity to break up incoming shot. However, against the more inferior AP quality used by some of the allied powers, the 1st ductile / brittle transition point would quiete frequently be expected to exhibit brittle events as well.

And finally, the use of Nickel, Chromium, Vanadium or Molybdenium as the most important alloys is a poor proxy for ballistic quality. All the alloys provide is hardenability, through-section hardenability, toughenability and extend or reduce times and temperatures for specific crystal phase transitions. This is seperate from hardness and toughness. Its always the heat treatment which transforms the steel into a specific crystalline structure, and hence, hardness (martensitic to tempered martensite in case of the more common thicknesses, safe thin plates which also employed austenitic structures with success). The metallurgic knowledge was good enough that they extracted good results with much leaner alloying than anybody else, probably forced by the shortage of ressources. Lean alloys were not significantly less strong under ballistic impact, and often better if made properly. The issue with lean alloys is that it requires tighter tolerances in the thermo-mechanical treatment, which resulted in more armor rejected by QC (f.e. records of TIGER-2 armor plate lots rejected by QC as late as march 1945, do not suggest to me that defective armor was simply passed through due to emergancy).

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