soviet armor steel database

Discussions on all aspects of the USSR, from the Russian Civil War till the end of the Great Patriotic War and the war against Japan. Hosted by Art.
User avatar
Alejandro_
Member
Posts: 357
Joined: 21 May 2003 13:26
Location: UK

Re: soviet armor steel database

Post by Alejandro_ » 21 Mar 2018 00:22

However, the T44, which in itselfe was a post ww2 tank which happened to be conceived and partially tested during ww2


It is actually not the case. It was not partially tested. The T-44 official entry into service was September 1944. And this is only a formality. Trials were so succesful that it was accepted into service even before they were finished (decree signed in July 1944).
was specified to resist domestic AP, and at one point had the requirements to include also german AP resistence.
What is the source for this information? The requirements for the new medium tank that led to the T-44 specify protection against 75 and 88mm shells. These were formulated at the end of 1943. As a matter of fact, I don't recall any ballistic testing carried out with Soviet guns (85/100/122mm) during development.
Btw, have You ever seen details of the Nashorn report? Have You ever seen and read it?
No, I have seen it mentioned a few times but 100mm@60° is a tough target. The book you mentioned states that 88mm Pak 43 was not capable of penetrating at more than 500 meters.
I have singled out this part because it deals with a different question. I am aware of what MBL-1 means, but we were not talking about MBL-1 (introduced in T62 and T55 turret casting).


T-62 and T-55 turrets were casted with MBL-2 steel.
The soviets adopted their new HHA ca. 1940 to replace the common RHA (i.e. armor with BHN ranging between 210 and 350 for most relevant section thicknesses). HHA beat their own shells much better up then common RHA could.

...

However, initially, it could only be made in small section thicknesses succesful with the chemical composition developed, leaving KV1 with it´s thicker sections with normal RHA instead.


In reality the T-34 choice was more based by the lack of nickel. At some point 8s steel had to be replaced by a different type due to lack of nickel
It´s 42SM. The same type of steel but treated to different hardness levels.
...
Of course, You may notice, that this is also why 42SM from older tanks is only chemically similar to 42SM while the same steel varies significantly in it´s physical properties from tanks made after the T54-3, particularely in terms of hardness, ductility and how hardness changed with section thickness.


Do you have a source for this? Usually the steel specifications is given depending on the yield strength. The hardness will be proportional to the tensile strength so it isn’t normally necessary to specify or measure both of them. This is of course for modern steel, after Euronorm EN 10202 revision.
You will find the 71L used for turret casting in Postnikov 2004, I have mentioned it already in this thread, You migth whish to look it up. HHA is confirmed by various post ww2 metallurgic analysis (glacis 444BHN, turret casting 448BHN, under relatively ductile state. My own reading with XRF from a museum exhib gives 435, 442 and 441BHN).


If you check Turi Pasholok latest article you will realize that several types were use. UZTM used a high hardness steel in the turret, Plant #200 70L. This is for the vehicles produced in late 1943-early 1944. I will check the book you mentioned anyway.

https://warspot.ru/11457-borba-za-mesto-na-konveyere
Somewhen in mid ww2 (1942-1943) they adopted "their new" HHA, (which they believed to be "superior" owing to the effect it had on their own projectiles)
As I said above, in these years the priority was to simplify and economise the design. The quality of the T-34s produced in 1942 deteriorated for a number of reasons.

Also, the USSR had access to Allied armour/steel, which was judged superior to their own in some features (less cracking/spalling). When examining steel used in US tanks captured in Korea it was judged superior to late war German as it had better viscosity.

Even German armour changed quite a bit during those 15 years you make reference. See for example face hardening in Panther tanks.

critical mass
Member
Posts: 227
Joined: 13 Jun 2017 14:53
Location: central Europe

Re: soviet armor steel database

Post by critical mass » 29 Mar 2018 14:08

Alejandro,

US manufactured CHA and RHA armor -of course- was a lot softer than any other ww2 nations armor products. Resistence to shock effects was a paramount specification. 2" cast armor was regularely tested against 4" shot to explore shortcomings in schock resistence.
This made it good against spalling (if treated properly) but poor against direct penetration (compare PAK43 vs M47 glacis in Yugo trials) and also inflicted less damage to the projectile, allowing wider angles of intact penetration (75mm pzgr 39 penetrating 132mm RHA plate at 45° intact in Aberdeen trials at velocities at which this projectile was rated only with this level of penetration at 30° when firing against german RHA).
Similarely soft material was also used extensively by german AFV during ww2: in the specification as protective mine bottom plating, where resistence to shock effect was more important than direct ballistic attack. Similar material was also used in soviet AFV after 1951: 43-PSM grade. As with german mine protective plating of ww2 vintage, it was not to be used where direct ballistic attack was feasable owing to the reduced ballistic protection it offered compared to normal RHA.

Soviet HHA worked according to entirely principles: they didn´t deform plastically but owing to their rigidity attempted to break up the attacking projectile. Penetration is by plugging entirely (the plate gives way very rapidly with little plastic deformation occurring before a disc is thrown), which made the armor good under conditions of projectile break up but very poor if it failed to break up the projectile and poor against overmatching attack. They started with 8S mass production of HHA for T34, a material which was ill suited for cast elements (it never was specified to be used for cast applications in the first place!) and then continued with thicker sections in IS.
70-L was specified to high hardness (брони высокой твёрдости 70Л), as was 71-L. It was virtually the extension of 8S hardness levels to much thicker sections. Unlike 8-S, it was particularely suited to cast applications, too. Notice that this is entirely new in the soviet AFV production -They could have continued with ordinary low hardness RHA /CHA armor production (KV1-KV85), but they choosed not to and replaced it with HHA at a time when the soviets had no suitably robust and capped, domestic test projectile to test HHA vs their principle threat: Pzgr39. Consequently, one of the early 70L test hulls suffered extensive spalling when tested with 76mm domestic guns in static tests on the prooving ground. None of the projectiles penetrated, as could be expected from the inferior projectile quality but the armor spalled massively and from all angles. Changes in tempering were thought to account for this problem but notice that the hull was never tested vs Pzgr39 before beeing submitted to mass production (big failure!).
Do you have a source for this? Usually the steel specifications is given depending on the yield strength. The hardness will be proportional to the tensile strength so it isn’t normally necessary to specify or measure both of them.
Pavlov/ Pavlov state that in their book. Glacis and side plate are 42SM grade but differed in hardness and thickness. (M-modified, originally there was 42-S grade medium hardness armor before research showed the same as german armor research did 15 years earlier), rear plate and roof plate were 49-S, bottom plate is 43-PSM and cast turret 74-L. All these plate´s properties are quite optimized for specific threats. It would be easier and less expansive to use a single material, at the expanse of some level of protection but economic considerations were not paramount here.

[qoqte]T-62 and T-55 turrets were casted with MBL-2 steel.[/quote]
Only late production T55B runs. MBL-1 was used in T55, T55A and T62 were MBL-1:
В 1954 г. для литых башен с толщиной стенок до 250 мм была создана сталь МБЛ-1 (Мариупольская броневая, литая — первая) с уменьшенным содержанием никеля и повышенным содержанием марганца и хрома, которую внедрили в серийное производство на заводах №174 и №200. В середине 1950-х гг. в московском филиале ВНИИ-100 (до 13 мая 1955 г. - ЦБЛ-1) разработали и в 1958 г. внедрили в серийное производство технологию термической обработки крупного броневого литья (литых башен), обеспечивавшую высокие боевые качества. Повышение противоснарядной стойкости (с 715 до 735 м/с) литых башен, изготавливавшихся из стали МБЛ-1 и 74Л, было достигнуто путем увеличения в них содержания углерода до 0,32-0,36%.
(...)
Эта сталь использовалась для изготовления башен танков Т-55, Т-55А и Т-62.
-Павлов/Павлов, "ОТЕЧЕСТВЕННЫЕ БРОНИРОВАННЫЕ МАШИНЫ 1945-1965 гг."
What is the source for this information? The requirements for the new medium tank that led to the T-44 specify protection against 75 and 88mm shells. These were formulated at the end of 1943. As a matter of fact, I don't recall any ballistic testing carried out with Soviet guns (85/100/122mm) during development.
At this time NII48 relied on calculations. These calculations require a plate-projectile fudge factor (De Marre) and usually do not hold vs real world results. The T44 hull was tested vs domestic guns in the soviet prooving ground:
[urlhttp://tankarchives.blogspot.de/2014/02/t-44-gunnery-trials.html[/url]

User avatar
Alejandro_
Member
Posts: 357
Joined: 21 May 2003 13:26
Location: UK

Re: soviet armor steel database

Post by Alejandro_ » 03 Jun 2018 22:37

Notice that this is entirely new in the soviet AFV production -They could have continued with ordinary low hardness RHA /CHA armor production (KV1-KV85), but they choosed not to and replaced it with HHA


This does not fit with the development path of IS tanks. This family did not derive from the KV-1/85 but KV-13, which was essentially a new design. It was also supposed to be universal medium tank, replacing both KV-1 and T-34.
At this time NII48 relied on calculations. These calculations require a plate-projectile fudge factor (De Marre) and usually do not hold vs real world results. The T44 hull was tested vs domestic guns in the soviet prooving ground:
[urlhttp://tankarchives.blogspot.de/2014/02/t-44-gunnery-trials.html[/url]


Where did you read that those tests were done with domestic guns? There is no information about it in that report. If you check Kolomyets book on T-44 you can read about the testing with German guns.
Only late production T55B runs. MBL-1 was used in T55, T55A and T62 were MBL-1:
I have lost the link I had but I will double check.
Pavlov/ Pavlov state that in their book. Glacis and side plate are 42SM grade but differed in hardness and thickness. (M-modified, originally there was 42-S grade medium hardness armor before research showed the same as german armor research did 15 years earlier), rear plate and roof plate were 49-S, bottom plate is 43-PSM and cast turret 74-L.

All these plate´s properties are quite optimized for specific threats. It would be easier and less expansive to use a single material, at the expanse of some level of protection but economic considerations were not paramount here.


Keeping the same thickness would not be more economical. You would end up with more weight (more alloys), more material needed for reinforced suspension and so on. Extra weight could lead to issues in transmission (bottleneck in the USSR at some stages) and questions on engine power output.

Economical considerations tended to focus on certain materials (aluminium in aircraft industry, nickel in tank industry) and finishing of components.

You jump to the T-54 when T-44 had already been fielded for a few years. If you take that 15 year difference it would mean that Soviets were using protection schemes from ~1929.

critical mass
Member
Posts: 227
Joined: 13 Jun 2017 14:53
Location: central Europe

Re: soviet armor steel database

Post by critical mass » 26 Jun 2018 18:20

This does not fit with the development path of IS tanks. This family did not derive from the KV-1/85 but KV-13, which was essentially a new design. It was also supposed to be universal medium tank, replacing both KV-1 and T-34.
The problem concerns the use of high hardness homogenious armor (rolled or cast) for thick section thicknesses. That was new in the IS-series for heavy tanks, after the T-34 series introduced HHA in medium tanks for smaller section thicknesses. The KV-series of predecessors did not had high hardness but normal hardness (rather soft) RHA instead. Whether or not the KV-13 can be regarded as a link betwee both IS and KV-series is entirely irrelevant to the question why they changed over from soft RHA to HHA midwar.
Where did you read that those tests were done with domestic guns?
In Yuri Pasholok´s original article.
Pavlov/ Pavlov state that in their book. Glacis and side plate are 42SM grade but differed in hardness and thickness. (M-modified, originally there was 42-S grade medium hardness armor before research showed the same as german armor research did 15 years earlier), rear plate and roof plate were 49-S, bottom plate is 43-PSM and cast turret 74-L.

All these plate´s properties are quite optimized for specific threats. It would be easier and less expansive to use a single material, at the expanse of some level of protection but economic considerations were not paramount here.

Keeping the same thickness would not be more economical. You would end up with more weight (more alloys), more material needed for reinforced suspension and so on. Extra weight could lead to issues in transmission (bottleneck in the USSR at some stages) and questions on engine power output.

Economical considerations tended to focus on certain materials (aluminium in aircraft industry, nickel in tank industry) and finishing of components.
Notice that I wrote about "material". How one can willingly read the sense of "thickness" into my memo is beyond me. Both terms mean different things, and I presume You know this. "Material" means the physical and chamical properties of the metal, "thickness" is only the section thickness. Your criticism was that economic consideration drove the T54 armor development. That´s clearly a poor representation of the development because they used several different plate materials and not one, and even used materials such as 42-SM treated to different hardnesses, depending on whether they were 100mm glacis or 80mm side plates.
These materials were not avialable to the T-44. The latter only used 42-S grade of uniform hardness. Unlike the T-54A´s 42-SM grade, the older 42-S didn´t differentiate the hardness in relation to section thickness or application and it was treated to slightly higher hardness than 42-S, which is not optimal in view of ballistic protection. All the critical research was conducted in the 1950-1954 timeframe. The latter 42-SM development closely mirrors german RHA R&D, though the germans arrived at these concluisons already during their R&D in the early 30´s, not in the late 40´s/ or even early 50´s as did the soviets.
But then again, the soviets didn´t use APC & APCBC until the early 1950´s either...
Post war trials conducted 1953-1954 by factory 183 to produce face hardened armor also relied on domestic (uncapped)100mm AP. For these trials, they used 42-SM (80mm) and 52-S grade steel (100mm plate) and one sided heated them during tempering. When shelled by 100mm domestic gun, the 80mm FH plate gave 525m/s critical velocity (at normal), which was 50-52m/s higher than present specifications, the 100mm plate exceeded specifications even by 55-90m/s. However, the face hardened material was not employed when tests with the newly adopted 100mm BR-412D APBCB showed inferior resistence to RHA.



MBL-1 was using an alloy with reduced Nickel but increased Chromium and Manganese content compared to previously used 90L- and 74L-grades.
Chromium wasn´t exactly aviable in plenty quantities. No.183 factory still used 74-L grade steel for casting the towers of T54B...
In an attempt to increase the resistence further, they again practiced what the germans did many years earlier: They increased the carbon content slightly from 0.24-0.31% to the range of 0.32-0.36% This research was finalised 1958 and raised the acceptance specification from 715m/s to 735m/s.

The original T54 (mod. 1947/8) turret when cast from 74-L was sensitive to even 85mm HE impacts as demonstrated by 1949 trials.

User avatar
Alejandro_
Member
Posts: 357
Joined: 21 May 2003 13:26
Location: UK

Re: soviet armor steel database

Post by Alejandro_ » 27 Jun 2018 12:44

In Yuri Pasholok´s original article.
Could you post the actual link? The material was translated in tankaarchives and there is no evidence of it. As I said before, you can find it in Kolomyets book.
These materials were not avialable to the T-44. The latter only used 42-S grade of uniform hardness. Unlike the T-54A´s 42-SM grade, the older 42-S didn´t differentiate the hardness in relation to section thickness or application and it was treated to slightly higher hardness than 42-S, which is not optimal in view of ballistic protection. All the critical research was conducted in the 1950-1954 timeframe. The latter 42-SM development closely mirrors german RHA R&D, though the germans arrived at these concluisons already during their R&D in the early 30´s, not in the late 40´s/ or even early 50´s as did the soviets.
This is wrong because 42SM armour was already available in the Objekt 701. Design of this tank started in Summer 1943, way before T-54. And also before T-44 requirements were published. How can this "critical research" have been conducted in 1950-54 if there was a vehicle that used it in the Summer of 1943?
Your criticism was that economic consideration drove the T54 armor development. That´s clearly a poor representation of the development because they used several different plate materials and not one, and even used materials such as 42-SM treated to different hardnesses, depending on whether they were 100mm glacis or 80mm side plates.
As I already mentioned the factories received an order to reduce the cost of the vehicles by 10-15%. The new casting used in T-54/55 turrets led to a reduction in cost of 3500 roubles and a reduction in molten steel of 2.5 tons. Are these not economic factors?

Also, the process of changing hardness has not been mentioned in any document as an economic factor. It would be more of a time factor. I already mentioned the economic considerations in previous messages.

critical mass
Member
Posts: 227
Joined: 13 Jun 2017 14:53
Location: central Europe

Re: soviet armor steel database

Post by critical mass » 28 Jun 2018 10:27

This is wrong because 42SM armour was already available in the Objekt 701.
(...)
Also, the process of changing hardness has not been mentioned in any document as an economic factor. It would be more of a time factor. I already mentioned the economic considerations in previous messages.
It wasn´t the same, if it was present then it was the same 42-S grade used on T-44. And neither objekt 701 nor T44 were "using" it in summer of 1943, these vehicles were drawing board exercises by then. The basic chemical mixture of 42-S has been described first earlier. But it´s the heat treatment which turns the steel into armor and therefore it´s incorrect to state that the armor was the same as that of later T54 plates. The T-54´s 42-SM armor was only finalised after trials 1950-1954 which demonstrated that it´s 42-S armor needed to be softened for optimum reistence against capped A.P. (M82 APCBC is mentioned). I suppose that prooves that the previous medium hardness 42-S RHA was ok vs domestic soviet uncapped AP.
This changed the physical properties of the armor while keeping the alloy combination. It´s not a big deal but mind that softening the armor is not just simply a "time factor" as You interprete it. The saving of metal has nothing to do with the change of hardness treatment of 42-SM. The softening of 42-SM is detremental from an economic point of view because softening RHA consumes way more energy (you need energy to heat up the plate to higher temperatures) and may make the product suspectable to temper britellness if insufficient care in controll of the cooling times is taken. It´s even more uneconomical if You use several, slightly different RHA steel grades on the same vehicle and even different hardness treatments within the same steel grade. Unlike RHA, high hardness armor is more economical because You can forego any sophisticated temper heat treatments with high hardness products. You only soften RHA the ideal hardness levels because You want to have a ballistically superior product, not because You want to have an economical cheaper product.

You have mentioned economic reasons in response to 42-SM RHA armor changes but You failed to understand that the argument You brought up was not for RHA but for turret CAST armor, and therefore the economic factors drving T54 turret armor changes is nothing but a red herring to the discussion of T54 hull armor. No 42-SM was ever used in T54 turrets my firend!

User avatar
Alejandro_
Member
Posts: 357
Joined: 21 May 2003 13:26
Location: UK

Re: soviet armor steel database

Post by Alejandro_ » 29 Jun 2018 12:36

Can you provide the link I asked for about the T-44 balistic testing? You have said that it was Yuri Pasholok´s original article. As I said before, the material was translated in tankarchives and there is no evidence of it. You can find specific data in Kolomyets book.
It wasn´t the same, if it was present then it was the same 42-S grade used on T-44. And neither objekt 701 nor T44 were "using" it in summer of 1943, these vehicles were drawing board exercises by then.
So, they use 42S armour but they decided to name it 42SM... :roll:
The T-54´s 42-SM armor was only finalised after trials 1950-1954 which demonstrated that it´s 42-S armor needed to be softened for optimum reistence against capped A.P. (M82 APCBC is mentioned).
Again, that is the conclusion you made from a test in which 42SM steel was modified, but it does not mean that the modification was serially introduced. 42SM steel was used in T-54 and T-55 hulls. If modifications would have been introduced they would have been documented as for the cast steel used in the turret.
have mentioned economic reasons in response to 42-SM RHA armor changes but You failed to understand that the argument You brought up was not for RHA but for turret CAST armor,
You failed to understand that factories were asked to reduce the cost of the vehicle by 10-15%. The use of a different cast armour is an example. This goes back to the first page of the topic.
This changed the physical properties of the armor while keeping the alloy combination. It´s not a big deal but mind that softening the armor is not just simply a "time factor" as You interprete it. The saving of metal has nothing to do with the change of hardness treatment of 42-SM.
Again, I did not say that "you save armour by changing the hardness". I have been very specific about the issues of Soviet industry for this case, which was mainly a shortage of certain alloying elements.
You brought up was not for RHA but for turret CAST armor, and therefore the economic factors drving T54 turret armor changes is nothing but a red herring to the discussion of T54 hull armor. No 42-SM was ever used in T54 turrets my firend!
I did not say anything about changes in RHA, see above and previous page. In any case, you seem to realise now that the changes in cast steel were driven by economical and technical requirements, and not by the Soviets deciding to "copy what the Germans did in the mid 1930s". Check the website where you read about the testing and try to find anything about this German influence.

Stiltzkin
Member
Posts: 704
Joined: 11 Apr 2016 12:29
Location: Germany

Re: soviet armor steel database

Post by Stiltzkin » 29 Jun 2018 17:46

I did not say anything about changes in RHA, see above and previous page. In any case, you seem to realise now that the changes in cast steel were driven by economical and technical requirements, and not by the Soviets deciding to "copy what the Germans did in the mid 1930s". Check the website where you read about the testing and try to find anything about this German influence.
Many developments are driven by technological and economical requirements but the world manufacturing output of the Soviets rose from 9% in the 30s to over 30% at the beginning of the 50s (how come, surely it has nothing to do with their occupation of nations like Czechoslovakia, East Germany and Poland). Do you really think they did not extract any technology from more developed nations during this period?

User avatar
Alejandro_
Member
Posts: 357
Joined: 21 May 2003 13:26
Location: UK

Re: soviet armor steel database

Post by Alejandro_ » 29 Jun 2018 20:11

Do you really think they did not extract any technology from more developed nations during this period?
Sure, and they waited until 1950-54 to apply it. Perhaps you have some documentation about this steel technology extraction?

Stiltzkin
Member
Posts: 704
Joined: 11 Apr 2016 12:29
Location: Germany

Re: soviet armor steel database

Post by Stiltzkin » 20 Jul 2018 18:57

Sure, and they waited until 1950-54 to apply it. Perhaps you have some documentation about this steel technology extraction?
Top
Well, development does not happen in an instant.
Here is an excerpt (and that is only the tip of the iceberg), not to mention that most of the Rocket programme was not considered domestic either and speaking of the nuclear programme, we have Klaus Fuchs (a Manhatten project participant and communist spy) who provided methods on enrichment (centrifuges) to the USSR and China, as mentioned before. That was exactly what they were lacking, industrial methods.

https://www.cia.gov/library/readingroom ... 313535.pdf
https://www.cia.gov/library/readingroom ... 0002-2.pdf
You do not have the required permissions to view the files attached to this post.

User avatar
Alejandro_
Member
Posts: 357
Joined: 21 May 2003 13:26
Location: UK

Re: soviet armor steel database

Post by Alejandro_ » 03 Aug 2018 10:01

Here is an excerpt (and that is only the tip of the iceberg), not to mention that most of the Rocket programme was not considered domestic either and speaking of the nuclear programme, we have Klaus Fuchs (a Manhatten project participant and communist spy) who provided methods on enrichment (centrifuges) to the USSR and China, as mentioned before. That was exactly what they were lacking, industrial methods.
Yes, but it does not say anything about the development of steel for armoured vehicles.

Stiltzkin
Member
Posts: 704
Joined: 11 Apr 2016 12:29
Location: Germany

Re: soviet armor steel database

Post by Stiltzkin » 08 Aug 2018 00:52

Yes, but it does not say anything about the development of steel for armoured vehicles
I am sure the Soviets have such a document, "we copied your designs"..... what are the odds that the steel properties are actually similar, post war? I think that is hardly a coincidence. The Soviets would be stupid not to take it, East Germany allowed them to catch up vis the West in various industrial processes. Quite frankly, the structure of the Russian economy vis the German one is almost identical today.

Mangrove
Member
Posts: 1702
Joined: 25 Dec 2004 01:33

Re: soviet armor steel database

Post by Mangrove » 11 Aug 2018 06:26

T-54 100mm D-10 barrel steel, according to 1961 Finnish analysis:

C = 0,33 %
Si = 0,28 %
Mn = 0,51 %
P = 0,011 %
S = 0,006 %
Cr = 1,26 %
Ni = 3,35 %

Return to “The Soviet Union at War 1917-1945”