BF-109 Metallurgical Quality?

[contrails16]

Hi all! Just a question that's been on my mind for a while. As I have mentioned in another thread, I love German tanks from WW2. However, I know from research that their armor plate manufacturing for tanks had some pretty bad quality control as well as things like sabotage and the works. One thing I am curious about is if the alloy they used for their warplanes like the Bf -109 were of good quality. What I mean by good quality is: not extremely brittle, and typically free of defects. I know that this may seem to be a strange out of left field question, but I am hoping to gather some input from the community on the metallurgical quality of the fighter planes used by the Luftwaffe such as the bf-109. If anyone happens to know whether their aviation industry had good quality control, that would also be awesome! Thanks!

 

[pbehn]

Hi all! Just a question that's been on my mind for a while. As I have mentioned in another thread, I love German tanks from WW2. However, I know from research that their armor plate manufacturing for tanks had some pretty bad quality control as well as things like sabotage and the works. One thing I am curious about is if the alloy they used for their warplanes like the Bf -109 were of good quality. What I mean by good quality is: not extremely brittle, and typically free of defects. I know that this may seem to be a strange out of left field question, but I am hoping to gather some input from the community on the metallurgical quality of the fighter planes used by the Luftwaffe such as the bf-109. If anyone happens to know whether their aviation industry had good quality control, that would also be awesome! Thanks!

Germany was always advanced in the field of metallurgy. In metallurgy many structures are named after German scientists, like the most brittle phase of Iron/Carbon, Martensite named after Adolf Martens. Johann Bauschinger considered by many to be the father of mechanical testing not so much for what he did personally but for bringing people from many fields together in a series of conferences. The main field of non destructive testing pre war was radiography which again had a strong German involvement. Ultrasonics started to develop during the war and again Germany was and still is strong in the field. The main problem they had was obtaining the metals needed for high temperature applications like nickel, chromium and molybdenum. You could say that that German engineers became expert in making things which they didn't have the materials to make, like jet engines.

 

[contrails16]

Germany was always advanced in the field of metallurgy. In metallurgy many structures are named after German scientists, like the most brittle phase of Iron/Carbon, Martensite named after Adolf Martens. Johann Bauschinger considered by many to be the father of mechanical testing not so much for what he did personally but for bringing people from many fields together in a series of conferences. The main field of non destructive testing pre war was radiography which again had a strong German involvement. Ultrasonics started to develop during the war and again Germany was and still is strong in the field. The main problem they had was obtaining the metals needed for high temperature applications like nickel, chromium and molybdenum. You could say that that German engineers became expert in making things which they didn't have the materials to make, like jet engines.

I agree they were quite talented. I still wonder though if their planes had qc issues in terms of alloy quality like the armor plate on their tanks. Thanks for the reply btw

 

[ssnider]

Does not really address your question, but does talk about German alloys

 

[contrails16]

Does not really address your question, but does talk about German alloys

Thank you

 

[pbehn]

I agree they were quite talented. I still wonder though if their planes had qc issues in terms of alloy quality like the armor plate on their tanks. Thanks for the reply btw

I cant think of any two things that are more different than a tank plate and a supercharged engines exhaust valve. What were the Germans "alloy problems" on tanks? The Allies had some problems with tank steel too, like an 88mm shell would go straight through the turret at 1000 yards. Then there was that awkward "ships splitting in two pieces just after launch" thingy.

 

[ssnider]

The Germans started out with very good Armor plate that for the most part was face hardened, From memory, early 44 or even late 43 they cut back on the Ni and Mn in the steel. It could still make good armor but the processing window was much smaller. It could result in steel that was too brittle. As 44 continued the Ni and Mn kept dropping as they had none. The Coupled with untrained labor, the resulting armor varied from very good to shattering on a single hit from even e 6 pounder. U.S, armor was softer than the any ones elses due to harded steel was almost impossible to cast. It had much less spalling though.

 

[davebender]

Germans started out with very good Armor plate that for the most part was face hardened
Face hardened RHA tends to work well when armor is thin. It does not work as well with thicker armor. That's why late war Germany switched armor types for medium and heavy tanks. I suspect the Soviets experienced a similar learning process. USA was different as our Shermans used cast armor, which has it's own plusses and minuses.

 

[Deleted member 68059]

Hi all! Just a question that's been on my mind for a while. As I have mentioned in another thread, I love German tanks from WW2. However, I know from research that their armor plate manufacturing for tanks had some pretty bad quality control as well as things like sabotage and the works. One thing I am curious about is if the alloy they used for their warplanes like the Bf -109 were of good quality. What I mean by good quality is: not extremely brittle, and typically free of defects. I know that this may seem to be a strange out of left field question, but I am hoping to gather some input from the community on the metallurgical quality of the fighter planes used by the Luftwaffe such as the bf-109. If anyone happens to know whether their aviation industry had good quality control, that would also be awesome! Thanks!

You need to be a lot more specific to get good data, the requirements for the airframe and powerplant are very different, and because the shortages were more pronounced in certain elements, will all be compromised to varying degrees. Broadly speaking, German metallurgy was essentially equal to anyone elses, the question will be where did production compromises and shortages come into play, and to answer that you need to at least be specifiying ferrous/non ferrous.

I am not an airframe specialist, but to the best of my knowledge german planes didnt start breaking up in mid air beause the aluminium used was bad, however huge numbers of engines DID fail in flight due to metal shortages. This is principally because a subsonic airframe only has to deal with achieving basic mechanical properties over a narrow temperature range. Engine parts however (especially valves) have to deal with high mechanical loads, and intense chemical attack, combined with very high temperatures. Therefore these tend to be the first parts to suffer from failure when the alloying elements become scarce.

Erhard Milch used to go and visit airfields to talk to the pilots and commanders, from 1942 onwards he reported things such as (paraphrasing):

"I visited the front last month, and *such and such* pressed a list of names into my hand, and said 'these are the names of the men who died because of your engines last month'"

It was a really serious buisiness, and did for Hans-Joachim Marsellie as well as many other top pilots.

 

[contrails16]

You need to be a lot more specific to get good data, the requirements for the airframe and powerplant are very different, and because the shortages were more pronounced in certain elements, will all be compromised to varying degrees. Broadly speaking, German metallurgy was essentially equal to anyone elses, the question will be where did production compromises and shortages come into play, and to answer that you need to at least be specifiying ferrous/non ferrous.

I am not an airframe specialist, but to the best of my knowledge german planes didnt start breaking up in mid air beause the aluminium used was bad, however huge numbers of engines DID fail in flight due to metal shortages. This is principally because a subsonic airframe only has to deal with achieving basic mechanical properties over a narrow temperature range. Engine parts however (especially valves) have to deal with high mechanical loads, and intense chemical attack, combined with very high temperatures. Therefore these tend to be the first parts to suffer from failure when the alloying elements become scarce.

Erhard Milch used to go and visit airfields to talk to the pilots and commanders, from 1942 onwards he reported things such as (paraphrasing):

"I visited the front last month, and *such and such* pressed a list of names into my hand, and said 'these are the names of the men who died because of your engines last month'"

It was a really serious buisiness, and did for Hans-Joachim Marsellie as well as many other top pilots.

True I should've been more specific there my bad, I was more curious in the airframe and outer skin, but power plant is interesting as well. I actually didn't know that some engines failed due to supply shortages. I did know that some engines had some issues that were a result of design flaws such as variants of FW-190's having overheating issues up until the A5 variant which allowed for more space where the engine was mounted. Thanks for the info

 

[pbehn]

Metals, especially steel have many varied properties. Hardness, tensile strength, toughness, ductility, brittleness. There are others like resistance to corrosion, fatigue and creep or loss of performance at high temperature. Whether high or low values for these properties are "good quality" depends on what you are using it for. Cast iron is brittle and hard not much use for anything but ideal for machine tool beds

It was a really serious business, and did for Hans-Joachim Marsellie as well as many other top pilots.

I don't know the story behind H J Marseille but his squadron were warned (according to wiki) not to use the new batch of aircraft. This suggests to me they had tried a "dodge" which caused engine failure or identified after the event where something had gone wrong with their QA/QC. With stainless steel today manufacturers will push the specification to the limit just because of the cost of Cr, Ni and Mo, if you ask for 0.5% Mo that is exactly what you get and if you ask for 3mm on a rolled coil you get 3 to 3.1mm. In wartime Germany the pressure to cut corners were much worse, it wasn't a question of cost, they just couldnt get the metals they wanted/needed.

 

[ThomasP]

Hey davebender,

re: "Face hardened RHA tends to work well when armor is thin. It does not work as well with thicker armor."

I think you have gotten the principal reversed. Face hardened armour works best with relatively thicker plate, the deciding thickness being about 4". If face hardened armour is to be of any use, it must have a relatively deep hard-face in order to deflect/damage the AP shell and reduce its penetration. The effect of face hardened armour at increasingly oblique hits (ie at other than 90°) increases dramatically more quickly than for homogeneous armour. This is one reason why all(?) the naval combatants used face hardened armour on the main belts of their battleships/battlecruisers, and on some (most?) of their cruisers with belts of about 4" or greater - it was unlikely that near-90° hits on the belts would be achieved at the expected decisive combat ranges.

Everything else being equal, below a thickness of about 4" an effective depth of the hard face is of too high a proportion to the thicker softer backing armour, and any shell that can come close to penetrating it is likely to shatter the face, which will then cause a significant cracking/weakening effect of the softer armour acting as backing for the hard face.

Using WWII alloys and technology, as the thickness drops below 3.5" it becomes significantly and increasingly more difficult to control the face hardening process and quality control becomes a serious issue. An example of this limitation is the occasional shattering of the Panther frontal glacis armour during the later part of the war.

The primary reasons for the Germans switching to homogeneous armor were the lack of access to necessary alloying elements, and the increased time needed for production of face hardened armour. Without the needed alloying elements it was somewhat pointless to attempt to manufacturer high quality face hardened armor.

One other factor that may have (probably did?) come into play in the German decision to switch to homogeneous (at least on the Panther) was the advent of the use of APC (Armour Piercing Capped) rounds. Once the Allies had sufficient APC rounds, face hardened armour became a pointless expense, as the difference in protective effect could sometimes be made up for with a lower cost, thicker homogeneous armour plate. The US never invested in face hardened armour for their tanks, partly due to the fact that the Germans entered the war with effective APC for their main AT guns.

 

[pbehn]

Hey davebender,

re: "Face hardened RHA tends to work well when armor is thin. It does not work as well with thicker armor."

I think you have gotten the principal reversed. Face hardened armour works best with relatively thicker plate, the deciding thickness being about 4". If face hardened armour is to be of any use, it must have a relatively deep hard-face in order to deflect/damage the AP shell and reduce its penetration. The effect of face hardened armour at increasingly oblique hits (ie at other than 90°) increases dramatically more quickly than for homogeneous armour. This is one reason why all(?) the naval combatants used face hardened armour on the main belts of their battleships/battlecruisers, and on some (most?) of their cruisers with belts of about 4" or greater - it was unlikely that near-90° hits on the belts would be achieved at the expected decisive combat ranges.

Everything else being equal, below a thickness of about 4" an effective depth of the hard face is of too high a proportion to the thicker softer backing armour, and any shell that can come close to penetrating it is likely to shatter the face, which will then cause a significant cracking/weakening effect of the softer armour acting as backing for the hard face.

Using WWII alloys and technology, as the thickness drops below 3.5" it becomes significantly and increasingly more difficult to control the face hardening process and quality control becomes a serious issue. An example of this limitation is the occasional shattering of the Panther frontal glacis armour during the later part of the war.

The primary reasons for the Germans switching to homogeneous armor were the lack of access to necessary alloying elements, and the increased time needed for production of face hardened armour. Without the needed alloying elements it was somewhat pointless to attempt to manufacturer high quality face hardened armor.

One other factor that may have (probably did?) come into play in the German decision to switch to homogeneous (at least on the Panther) was the advent of the use of APC (Armour Piercing Capped) rounds. Once the Allies had sufficient APC rounds, face hardened armour became a pointless expense, as the difference in protective effect could sometimes be made up for with a lower cost, thicker homogeneous armour plate.The US never invested in face hardened armour for their tanks, partly due to the fact that the Germans entered the war with effective APC or their main AT guns.

Interesting stuff. Was there a definition of "homogenised" or "homogeneous" in terms of 100mm or 4" plate at the time? To my mind it would have massive differences in grain size at least from mid wall to surface.

 

[contrails16]

The Germans started out with very good Armor plate that for the most part was face hardened, From memory, early 44 or even late 43 they cut back on the Ni and Mn in the steel. It could still make good armor but the processing window was much smaller. It could result in steel that was too brittle. As 44 continued the Ni and Mn kept dropping as they had none. The Coupled with untrained labor, the resulting armor varied from very good to shattering on a single hit from even e 6 pounder. U.S, armor was softer than the any ones elses due to harded steel was almost impossible to cast. It had much less spalling though.

yeah, which is sad. I know the engineers and specialists worked hard to find ways to make better armor plate with less, hence, they ended up with armor plate that had a significantly higher carbon content than anything the Allies had ever seen before in combat. Yet, despite this high carbon content, they had apparently devised a way to make the armor just as strong as when they had access to better alloy...but this method of forging the armor was very complex and could be messed up quite easily. Some metallurgical reports conducted by the USA found that there were signs of rapid cooling and improper forging techniques which led to cracks that could easily expand under ballistic fire.

 

[davebender]

Face hardened armour works best with relatively thicker plate
It is my understanding that tanks with face hardened armor tend to shatter the outer (i.e. hardened) portion when hit by by a heavy non penetrating hit. This could happen even from HE artillery fire.

I have no idea how this plays out for battleship belt armor 12 inches thick. Most WWII era tank frontal armor was only 45 to 80mm thick.

 

[Acheron]

Apart from the lack of raw materials, wasn't the increased use of slave labor also an issue? From what I heard, said workers didn't seem very motivated to do a good job for a military hell-bent on exterminating their people.

 

[Denniss]

Marseille and other pilots were not lost because of metallurgical issues but due to an oil foaming problem which interrupted the oil flow in the engines which then led to them blowing up.

 

[ThomasP]

Hey davebender,

It is true that face hardened armour is more likely to break/crack when hit by relatively large projectiles (relatively large to what the armour was designed to defeat) than homogeneous armour of the same thickness. And if a large enough HE round is used breaking/cracking can be induced. But the effects of AP projectiles/HE explosions large enough to cause such failure on 80-100mm (Panther) or 150mm (Tiger II) thick face hardened plates will cause far more damage to thinner face hardened plate - unless the failure is due to quality control issues.

Also, larger unsupported area/spans of plate are more likely to shatter/crack than smaller better supported plates. Pictures of the large face hardened glacis plates on the Panther and Tiger II are often used as examples of this kind of failure. This kind of failure did occur on the smaller mantlet and driver's glacis face hardened plates, such as on the Tiger I, but it was significantly less common - partly due to better quality control (most Tiger I armour having been made when the necessary alloying elements were available) and partly due to the fact that they were better supported.

Breaking/cracking/tearing mode of failure also occurs on homogeneous plate, if the AP projectile/HE explosion is large enough. For example, there are photos online of Sherman rolled homogeneous glacis plates that have been hit by large AP projectiles/HE explosions and broken/cracked/torn, along with photos of the homogeneous side armour with similar damage. Some of these failures were due to quality control issues and some due to the size of AP projectile/HE explosion

Something that should be kept in mind is that the AP projectiles that caused the break/crack failure on the Panther/Tiger II face hardened armour would have easily penetrated the homogeneous armour on a Sherman (no, I am not saying the Sherman was a bad tank, just that it was not anywhere as well protected as the Panther/Tiger tanks). And comparable HE explosions would cause far more damage to a Sherman.

 

[pbehn]

Hey davebender,

It is true that face hardened armour is more likely to break/crack when hit by relatively large projectiles (relative large to what the armour was designed to defeat) than homogeneous armour of the same thickness. And if a large enough HE round is used breaking/cracking can be induced. But the effects of AP projectiles/HE explosions large enough to cause such failure on 80-100mm (Panther) or 150mm (Tiger II) thick face hardened plates will cause far more damage to thinner face hardened plate - unless the failure is due to quality control issues.

Also, larger unsupported area/spans of plate are more likely to shatter/crack than smaller better supported plates. Pictures of the large face hardened glacis plates on the Panther and Tiger II are often used as examples of this kind of failure. This kind of failure did occur on the smaller mantlet and driver's glacis face hardened plates, such as on the Tiger I, but it was significantly less common - partly due to better quality control (most Tiger I armour having been made when the necessary alloying elements were available) and partly due to the fact that they were better supported.

Breaking/cracking/tearing mode of failure also occurs on homogeneous plate, if the AP projectile/HE explosion is large enough. For example, there are photos online of Sherman rolled homogeneous glacis plates that have been hit by large AP projectiles/HE explosions and broken/cracked/torn, along with photos of the homogeneous side armour with similar damage. Some of these failures were due to quality control issues and some due to the size of AP projectile/HE explosion

Something that should be kept in mind is that the AP projectiles that caused the break/crack failure on the Panther/Tiger II face hardened armour would have easily penetrated the homogeneous armour on a Sherman (no, I am not saying the Sherman was a bad tank, just that it was not anywhere as well protected as the Panther/Tiger tanks). And comparable HE explosions would cause far more damage to a Sherman.

Was the temperature at the time noted or considered important?

 

[ThomasP]

Hey Acheron,

The use of slave labor would not (I think) have had much adverse effect on the quality of armour plate - unless sabotage was involved, which would have been difficult to achieve without being noticed. The parts of the process important to quality control would have been overseen/performed by a small number of technically expert personnel, with the large majority of workers being relatively unskilled even in peacetime. Resistance from forced labor could, however, easily affect the speed and/or volume of production.