Rust

[Pig of the Week]

3 minutes ago, Tim R-T-C said:

I think there would be great scope for a book or series of books on realistic weathering - not a how to achieve the results book, there are plenty of those - but one with pictures of real tanks and planes and indications of where different tanks and planes actually show weathering and corrosion.

 

For example, where on a Spitfire would you expect to see oil leaks, fuel stains, scratches etc in normal use.

 

Where on a T-62 would you get rust and scratches in normal use, then on an abadoned example?

Hence always look for actual pictures of the real life prototype for reference, one good aspect of the Internet that so much is out there if you look... 

[Tim R-T-C]

20 minutes ago, Pig of the Week said:

Hence always look for actual pictures of the real life prototype for reference, one good aspect of the Internet that so much is out there if you look... 

 

True, but I'd be very happy just to be able to pull a reference book on WW2 US Aircraft and check for exhaust stains positions on an F4F Wildcat, than having to scroll through a dozen websites and 500-post Britmodeller threads to get there!

[Kingsman]

The problem with the many weathering booklets available so far is that they are almost universally produced by model paint companies with products to sell, and promote the use of those products.  The models and techniques therein are most usually showcases of individual modellers' models and techniques, using of course the sponsor company's products.  This is not to decry their usefulness, but to question their purpose and editorial philosophy.  Bolting together a series of individual models does not necessarily achieve the aim of the publication unless they are commissioned and curated to serve that purpose.  And IMO there is far too much emphasis on artistry.

[Graham Boak]

Oh, emphatically yes.  I recently bought the AK book of Japanese AFVs.  After all there aren't a lot of English works on the subject.  I feel that I wasted my money.  Most of the kits being made were (fair enough) in large scales than I would want to see, and more importantly the superb modellers involved had all used their individual mixes for the Japanese colours involved, none of them using the specific AK Japanese colours advertised within.  No reference to what the colours should have been, or any comment on IJA practice.   Ho hum.  If there's a modeller who's a complete novice on Japanese subjects they might find this book a nice picture guide to ... well, something.  Do get in touch.

[Bozothenutter]

On 1/29/2024 at 7:28 PM, Pig of the Week said:

Fair comment @Kingsman.... I'd think any structural welding on armour would've been arc welded for sure, gas would've probably been used more as a cutting medium, as per some of the rough looking edges on exposed plates on German tanks particularly. The Russians too were more interested in knocking out as many tanks as possible without much regard for fine finish! 

Imagine welding those huge plates!

What current would they have used, what size electrode, how much slag was produced?

What was the penetration needed?

Welding from both sides?

How much pre- heating was needed?

How was cooling done/monitored?

How was the weld checked?

With those sizes, how would you correct deformation?

 

Soo many questions!

[Graham Boak]

Huge?  How about the ship welding that was done?

[Pig of the Week]

I've seen some fairly shoddy looking welding on tanks tbh, one ww2 British thing in a tank scrapyard I saw years ago looked very dodgy! 

They might have found the massive thick plates to be not too much of an issue distortion wise, purely as the plates are so hefty, you get more problems with distortion on thinner materials. 

I'd guess they'd likely be using 4mm rods or something. 

[Tigerausfb]

It

On 2/1/2024 at 11:06 AM, Bozothenutter said:

Imagine welding those huge plates!

What current would they have used, what size electrode, how much slag was produced?

What was the penetration needed?

Welding from both sides?

How much pre- heating was needed?

How was cooling done/monitored?

How was the weld checked?

With those sizes, how would you correct deformation?

 

Soo many questions!

200A @ 380v and 5mm graphite rods evidently.  It's all in here, hours of reading.....and translating. An article in the popular weekly magazine (available at all good newsagents) Bulletin Of The Tank Industry by V.V. Ardentov called 'The German experience in the cutting armour of and welding of tank hulls' based on a visit to a couple of captured panzer werk. I know nothing about welding so I'm not taking questions. Don't forget the USSR's manufacturing was pushed further and further east so any workforce they could get was pretty much Johnny No-Stars and they had to adapt their processes as such, with automatic welders. The Germans had a more settled workforce in the tank factories and welded manually.

 

Edited February 4 by Tigerausfb

[Kingsman]

From a Facebook page.  An M4A2 that's been sat out in the open on Guadalcanal for 80 years.  No Sherman in WW2 was ever more than 3 1/2 years old.  Note the still-bright welds.

 

[stevehnz]

3 hours ago, Tigerausfb said:

200A @ 380v and 5mm graphite rods evidently.  It's all in here, hours of reading.....and translating.

I've often wondered this, having held arc welding tickets in my younger days, all three orientations, it was a question that had some professional interest for me.

 

3 hours ago, Tigerausfb said:

The Germans had a more settled workforce in the tank factories and welded manually.

I wonder just how true this is? Late in the war, it is my understanding that much of German industry was staffed by forced labour from occupied countries or slave labour from concentration camps with a fairly bad outcome for quality control, at least for subjects I've read about.

Steve.

[Tigerausfb]

42 minutes ago, stevehnz said:

I've often wondered this, having held arc welding tickets in my younger days, all three orientations, it was a question that had some professional interest for me.

 

I wonder just how true this is? Late in the war, it is my understanding that much of German industry was staffed by forced labour from occupied countries or slave labour from concentration camps with a fairly bad outcome for quality control, at least for subjects I've read about.

Steve.

I think late war the gloves are off and not a subject I wish to discuss as we're going totally off-topic there but welding's a specialised skill, here it was a reserved occupation over the age of 23. 

[Pig of the Week]

It perfectly possible to show someone (who's not a complete idiot) fairly quickly how to do usable non critical welds in a basic downhand position, I've shown a number of lads to do just this in the past.

Certainly much of German industry relied on forced labour as mentioned above, naturally you're not going to get very good work from people under those circumstances, plus there's the element of deliberate sabotage to consider. 

Doing decent quality positional welding to a specification is of course a skilled occupation and essential in the production of military hardware. 

[Hunker]

On 2/4/2024 at 10:05 PM, Kingsman said:

From a Facebook page.  An M4A2 that's been sat out in the open on Guadalcanal for 80 years.  No Sherman in WW2 was ever more than 3 1/2 years old.  Note the still-bright welds.

 

 

I may be wrong on this but the early shermans up to about 1943 used cast iron hulls, so welding rods used would have contained nickel, which doesn't rust.

[Hunker]

And if anyone wants to know precisely how German tanks were welded during ww2, here is the answer.

https://en.topwar.ru/169350-svarka-tankovoj-broni-nemeckij-opyt.html

 

This is the link for Tigerausfb's post. 

You can see clearly the interlocking fit on the armour to give it more strength.

Edited February 6 by Hunker

[Kingsman]

6 hours ago, Hunker said:

I may be wrong on this but the early shermans up to about 1943 used cast iron hulls, so welding rods used would have contained nickel, which doesn't rust.

Yes you are wrong, on 2 counts.  Firstly, no Sherman ever used a cast iron hull.  Not even the T6 prototypes.  Cast steel of an armour quality alloy was used: no I don't know the alloy recipe.  Small parts were welded on and flawed castings with surface defects were frequently repaired by welding and grinding.  So you'd be looking at welding rod suitable for high-quality steel.  You are hard put to find one without some form of repair, most likely where sand was dislodged from the mould when the master was removed and the mould halves re-joined or the molten steel was poured.

 

Secondly, cast-hull Shermans were manufactured for the entirety of production and the cast hull transitioned to the 2nd generation "large hatch" configuration and 76mm gun in early 1944.  The very last Sherman to be built, in August 1945, had a cast hull.  As did the very first one to be built in February 1942.  The first 76mm Shermans to see action - during Operation Cobra in late July 1944 - had cast hulls.

 

The Sherman design did originally call for the cast hull and the T6 prototypes were cast, but the realisation that only 1 single foundry could cast it - Continental Steel - necessitated a redesign to allow a fabricated-hull version.  Turrets were always cast, as were many small parts.  Later General Steel joined in hull casting, and later still Pittsburgh Steel.  Of the 49,000-odd Shermans built, about 9,000 had cast hulls.

 

As for Germany, yes they did try to keep their skilled factory workers in factories.  Bringing in women as the Allies all did was not practical as Germany relied on small family farms and with the men all away fighting the women were running the farms and feeding the nation.  But from 1943 onwards factory workers were increasingly conscripted and replaced with volunteer or forced labourers without the skills and training.  And material quality was falling away.  The interlocking of armour plate joins was a direct response to increasing failures under projectile impacts, or even general running, of the butt welds previously used.

[Harry_the_Spider]

Fascinating.

 

I’ve recently had a go at ARVs after years of doing aircraft and personally think that something absolutely covered in rust may be beautifully painted, but it looks a little unrealistic unless it depicts a vehicle that has been burned out or left underwater for a few decades. I’m just doing mine “dusty”.

 

A good point was made about Mr Hewes. They’ve been pulling things out of fields that have sat there for 30 odd years and, whilst they are covered in all sorts of muck, there is very little rust.

[Pig of the Week]

7 hours ago, Hunker said:

And if anyone wants to know precisely how German tanks were welded during ww2, here is the answer.

https://en.topwar.ru/169350-svarka-tankovoj-broni-nemeckij-opyt.html

 

This is the link for Tigerausfb's post. 

You can see clearly the interlocking fit on the armour to give it more strength.

Very interesting reading 👍

[Hunker]

5 hours ago, Kingsman said:

Yes you are wrong, on 2 counts.  Firstly, no Sherman ever used a cast iron hull. 

Yes you're right. Got my casts mixed up. 

As far as the rod goes, nickel rods can be used to weld cast steel and probably were used on the sherman, although I can't find any specific info on exactly what rod they did use. It would have been arc welded though, and being that thick probably even pre heated.

 

[Kingsman]

Would pre-heating have been necessary for attaching small parts to the surface?  I can perhaps see it for repairing casting flaws.  We're talking about lifting rings - very substantially attached - footman loops for stowage, cable clamps, light guards, fuel filler hinges and locks, gun travel lock.  Light stuff.  Apart from the sheet metal light guards and bent rod footman loops these parts were also castings.  Although bent rod lifting rings also existed.

 

I might be worried about applying area heat treatment to an an armour casting for fear of affecting its properties.  Oddly, I have not been able to get to the bottom of whether US turret and hull castings were heat-treated after pouring.  I assume they must have been in order to harden them.  I have seen it said that they were made from Rolled Homogenous Armour (RHA).  But that is a sheet material hot-rolled at great pressure to alter and homogenise the crystalline structure of the steel to full thickness: hence the name.   Fabricated Sherman hulls were certainly made of this.  But re-smelting RHA to cast it would destroy the effect of the hot-rolling and return the steel to being un-hardened.  Surely armour castings must have been heat treated after pouring, effectively making them vace-hardened armout (FHA).  Or were the crystalline changes in RHA permanent?

[Hunker]

Well you usually preheat to allow a uniform cooling action and to prevent cracks in the weld. Smaller items like hinges and guards wouldn't need it but lifting hooks and towing hooks need strength in the welds to prevent failure so quite possibly were heated. 

Also by preheat it doesn't mean heating the steel up to cherry red or anything close to that which most certainly would draw the temper. There are tables that state the temp of the preheat that would be adhered too, in the factories at least. Repair or add on armour in the field would be another matter. 

[Tigerausfb]

We need a metalurgisterist in this thread!  Very interesting reading chaps.  Just had a cursory flick through the breeze block that is Hunnicutts 'Sherman' and no mention of the armour alloys, just rolled and cast homongenous armour at xx°. The answer might be in Rich Andersons upcoming 'American Thunder: U.S. Army Tank Design, Development, and Doctrine in World War II' released next month.

[StuartH]

Rather detailed but this is the Welding operations US Army course OD1651 which may be of interest:

 

https://opensourcemachine.org/wp-content/uploads/2008/10/welding-operations-us-army-course-od1651-part-1-ww.pdf

[Kingsman]

2 hours ago, Tigerausfb said:

cast homongenous armour

And that is precisely the conundrum, at least in my mind.  How can you re-smelt and cast RHA - a sheet material - while retaining the qualities derived from the hot-rolling?  Armour alloy recipes varied by country and time but would have contained elements such as carbon, manganese, chromium, nickel and molybdenum.   More recently Germany has been using tungsten instead of the comparatively rare and hard to refine molybdenum.  Never heard of it?  It is one of the most effective elements for increasing hardenability of iron and steel and it contributes to the toughness of quenched and tempered steels while having high corrosion resistance.  The USA and the wider Americas including Canada were and are the major source of it, so I imagine that US armour alloys contained it.  Can't see Germany getting its hands on much.

 

But I think I may have happened across the answer - and demonstrated my own ignrance in the process - which is to ignore the word Rolled.  It seems that the US came up with a new way of hardening armour castings that resulted in an almost fully uniform quality to full thickness rather than the face-hardening that might traditionally have resulted.  So, homogenous.  But without the hot rolling and the crystalline change imparted by it.  Ding!  Penny finally drops.........  D'oh.......

 

I hadn't found this site before, where it is all made clear.  https://amizaur.prv.pl/www.wargamer.org/GvA/background/armourtypes3.html#:~:text=Cast armor is never worked,structure and lower ballistic resistance.&text=Cast armor is always homogeneous,apart from a few experiments).

 

I'm going to quote directly from it to save you flicking over.

 

"Cast armor is never worked or squeezed down into thinner form as rolled armor is, therefore it has an inferior grain structure and lower ballistic resistance.  Cast armor is always homogeneous and was never face hardened (apart from a few experiments). The difference in hardness between the outer surface and inner surface found on some cast armour is more a result of poor heat treatment or insufficient alloy content than any intentional effect intended to increase ballistic resistance.

 

Homogeneous armour works best when it is the same hardness throughout, as changes in hardness form stress concentration boundaries which significantly degrade ballistic resistance. It was not until the Sherman got well into production that the USA learnt to control the hardness of varying thickness castings by hitting the thick parts with water jets during the quenching process. This cooled the thick parts so they were better quenched, and consequently were harder than they would be if they had simply immersed the whole casting into still water.

 

The chemical composition of cast armour is thus much the same as RHA but its quality is inherently more variable and the thickness of the casting cannot be controlled as accurately. Cast armour is also at a disadvantage because it is generally of complex shape and varying thickness and cannot be given uniform heat treatment, which has an adverse effect on its ballistic properties.

 

On the other hand, cast armour is more readily fabricated into complex shapes than RHA plates. It facilitates an efficient distribution of armour as well as allowing a reduction in the number of welded joints and the preparation that goes with them. The ultimate demonstration of this is provided by turrets and hulls that are cast in one piece, but the size of such castings is apt to tax industrial resources.

 

Cast armour resists less well than rolled armour of the same hardness and thickness. USA tests of production quality armour in 1942 and 1943 clearly shows that cast armour resists less well than RHA of the same hardness and thickness. Cast armour 51mm thick showed a 15% to 20% inferiority compared to 51mm RHA plates when hit by 75mm projectiles. The tests also demonstrated that RHA can be raised to higher hardness levels than cast armour without losing ductility, and therefore ballistic resistance.  The USA accepted the lower ballistic quality of cast armour when manufacturing the M4A1 Sherman, relying on a little extra thickness and the rounded corners to make up for the essential weakness of the armour material. The net effect was that the later versions of M4A1 Sherman were less well protected than the later versions of RHA Shermans. One unit which had both, the 743rd Battalion, kept their cast hull Shermans out of combat, a lesson apparently learned the hard way."

 

So now we know.

 

And we also peek into why armour steel of any type does not corrode anything like as rapidly as milder steels (bringing us back into the room) as the alloys contain naturally corrosion-inhibiting elements.

 

But it is interesting that "well into production" is mentioned for the new process to be adopted.  Which opens the possibility that the M4A1s shipped to British forces in N Africa and those used by US forces in Tunisia had inferior protection.  Not substandard as such, but not as good as later.  The initial 2 shipments to British forces in July 42 comprised almost the entirety of Sherman production up to that time, A1s and A2s.

[Hunker]

1 hour ago, StuartH said:

Rather detailed but this is the Welding operations US Army course OD1651 which may be of interest:

 

https://opensourcemachine.org/wp-content/uploads/2008/10/welding-operations-us-army-course-od1651-part-1-ww.pdf

 

Except for the chapters on welding armour, the manual is remarkably similar to the one I was given when I went to welding school in the early eighties!

The parts that are pertinent to our conversation about welding I have cut and copied here. 

 

5. Welding Homogeneous Armor Plate a. General. Before welding damaged armor plate, the type of armor must first be identified. This identification can be accomplished in the field by one of the methods described in paragraph 2c on page 63. Homogeneous armor plate can be satisfactorily welded using the electric arc welding process and 18-8 stainless steel heavy coated electrodes with reverse polarity. Armored vehicles that have been exposed to conditions of extreme cold should not be welded until the base metal has been preheated sufficiently to bring the temperature of the base metal in the zone of welding up to no less than 100 F. At this temperature, the metal will be noticeably warm to the touch. If this preheat is not applied, cracking will occur in the deposited weld metal.

 

c. Armor Plate Welding Electrodes. (1) The most satisfactory method for the repair of homogeneous and face hardened armor plate is the arc welding process with stainless steel electrodes. (2) In the oxyacetylene welding process, a large section of base metal must be heated to maintain a welding puddle to weld satisfactorily. This heating destroys the heat treatment of the base metal, causing large areas to become structurally and ballistically weak. In addition, this process is slow and produces considerable warpage of the base metal. (3) Initially, developments in armor plate welding required the use of stainless steel electrodes containing 25 percent chromium and 20 percent nickel. Further developments served to produce electrodes with a core of 18 percent chromium and 8 percent nickel, and a coating of manganese or molybdenum, or both, which produce excellent results. These electrodes are known as manganese modified 18-8, and molybdenum modified 18-8 stainless steel electrodes. They can be used for welding all types of armor plate by the electric arc process without preheating or postheating the base metal structure.

 

[Black Knight]

On welding; I had an uncle who worked for Shorts & Harland during the war. He actually spent his working life there. He was a senior Boiler Maker & Welder

Harlands built AFVs during the war, as well as ships and aircraft. And from time to time my uncle had to go to the other construction areas.

My uncle told me of a welding process used on the AFVs which I didn't really understand until I saw it used by Northern Ireland Railways about 10 years ago

A fillers and magnesium paste (and other stuff) was applied to the joint and covered in clay. Then an electric current was applied, The paste burnt fast and hot, The clay was knocked off and you had your weld. The clay confined the heat in and on the joint. The speed the paste burnt at the other parts hardly had time to get hot

N.I.R. used the same type of welding when they joined all the individual track lengths. They applied the paste, put a safety cover over it, applied electric current, moments later the tracks were welded. A worker used an angle grinder to smooth the weld as this was a rail track. But there was minimal grinding to do, the welders had got the amount of paste just right