MIG for Cast Iron + Small Welding Table

[warmstrong1955]

Apparently you didn't get the memo...... The one with the most toys wins!

[JackF]

I'm glad I followed this post. I need to get some S/S wire or tig filler rods for cast iron and give it a try.



Jack.

[SteveHGraham]

This week I watched a show where they restore tanks. If I understood what they were saying, they were welding huge cast parts. The guy who was explaining it said he wanted to make it authentic, so he was using stainless filler...just like they did at the factory. So it looks like stainless filler and cast iron have been used together for quite some time.

I don't know if he preheated, but how much can you preheat a tank turret?

[steamin10]

In the first place early tanks, and most german early series tanks, were fabbed from flat rolled ship armor, something they understood. German SP guns and various early Panthers had finger joint corners, that were welded over, and not finished too fine, to meet production rates. Stuart and similar early US tanks were riveted and that process was left behind for the more sturdy welding of flat plate, as many hulls for the M-3 and its variants, Firefly, and others, were often flat plate assembled at various plants without casting abilities. The turrets were cast or fabbed according to the uses, and were of tool steel quality with Chrome, and conditioners to make the armor. I assure you cast iron, is useless, when tried as armor, it is cast steels of various grades, and heat treated to tear and not shatter on impact. Low carbon steels, or bolt quality steels of high carbon are nearly as useless when subjected to solid rounds, as they cannot withstand the kenetic energy transfer. In history, the Germans streamlined their production, and eliminated many smaller guns, and simplified their production around the Krupp 88 mm guns. While technically wasteful of materials, it became an ace in the hole that became an all purpose gun with many abilities that could dominate a battle field with supperior range and destructive power above adversaries. Up gunned German tanks could easily destroy the M3 on the run, at extended ranges. because the M3 simply was no match for that ammunition. It was only volume of numbers that flooded the field that brought defeat to overwhelmed German forces.

Any way, to make a solid repair on tool steel base material, you use stainless wire of appropriate formula. All the weld repairs (hot tears, blows, surface leafs) on M-60 tank hull parts and turrets, were done in a proprietary stainless wire, by mig and stick. all fittings and lift eyes were done similarly. The assemblage of an M-60 hull weighs about 20 for the frontal slope casting, and the turret had to make 19.5 for minimum weight. The finish assembled hulland is comprised of 5 pieces jig fitted and stick welded together. two rolled armor belly plates are fitted to a forward nose section with top turret ring, followed by two side plates. These pieces are precision flame cut and fitted out in a jig/layout table, and all reference points are marked. Assembly is in a turnover (rotisserie) and all welding is essentially flat for control purposes, and final machining of all drive ports and suspension points are machined in, before we sent the finished hulls to the assembly plant. All parts were heat treated before welding, and no post treatment was done.

We cast the first base rings for the 'new' M1 Abrams, that is of a layered and stratified armor. It process is secret, although it can be discerned it includes ciramics, and has rarely been defeated in battle it is that good. Various units have been defeated from other failures, but the armor, as a system is the best in the world.

[SteveHGraham]

That's a lot of information. So the cast stuff on a WWII tank would have been steel, to prevent shattering?

[steamin10]

A conditional yes is your anwer. The shermans that flooded the European theater, were of mixed heritage, with some mods being made depending on Date and plant of origin. It was designed to be Medium tank that could cross any country bridge, fit down narrow streets, and have good speed over rough terrain. As designed they were to be of cast armor jull and turrets for best protection, but lagging prodution forced various production methods to get numbers into the conflict. Overall, known and proven mechanicals helped front line units repair and salvage knocked out units, to be recrewed and sent back into the fight. Something like half of all units that recieved knockout damage, 19,000 units, were repaired, and sent back into action. Truly amazing history, if you care to read up some. The feared Panther V, vaunted the 'Most advanced tank of the war' was based on the Stu ll chasism a 36 ton unit, making the 45+ ton Panther a mechanicl joke. So it was with much of the German rush to improve and lead the game in innnovations. Sadly, the Shermans were dated by produstion time, and minor tweeks did nothing for the lost crews. Fighting a Sherman against suerior aror, was an art, but then its role was infantry support and breakout.

Actual tank on tank duals, were fewer than one would believe, most on either side being lost to air attacks, field gun ambush, and hand infantry weapons. The panther V could be destroyed by putting an 8 inch wooden log into the moving tracks. The drive gears would not withstand the strain, and would fail.

Sorry to get windy, this was about welding, and castings, rolled plate, and assemblies that were commonly welded, even with the relatively primitive methods used back then. Welding was still a young art then, and somewhat mysterious. All welded Liberty ships, would break in half in rough seas due to failed welds, and design streses, but the technology grew up from it. Now common guys like me have 4 machines, and TIG weld things only Buck Rogers could dream about back then.

Times change, and we must move with the times.

[GlennW]

A friend called earlier today and he had a broken cast iron casting that he had repaired previously and it broke again. He then took it to a repair shop and they had sat on it for a week and did nothing. Not my type of work, but I told him I would look at it for him as he was desperate for it and I had bought some odd alloys of TIG filler rod a while back when I was in a welding mood and had not tried them yet. He showed up with this large 75 lb casting that was part of a wood working machine that had an ear broken off of a clamp type of affair that held an electric motor in place that had been MIG welded back on and broken again. I ground the tar out of it to remove the bunched up MIG weld and TIG welded it back together with this rod that I had bought. The first try I stepped on the pedal to put some heat in it and tried a bead to see what it would do and it just fizzed like cast iron does with a TIg torch. So I backed off and tried more of a brazing technique and it flowed right out and made a nice weld so I figured what the hell, weld on! I ground off my test weld and fixtured the broken ear in place and welded it al around and it welded nicely. The I cut a pair of steel gussets to support the ear a bit better and welded them in place and it welded the steel to the cast iron just as nicely. After it was done there was no "tinking" or "clinking" like it does just before it cracks and falls off again, and I was quite happy with the way it flowed together. I let it cool a bit and whacked it with a hammer and damn if it didn't stay there.

After I was done I looked at the rod designation and Googled it and this is what it is.

http://www.midalloy.com/wp-content/uplo ... e-Wire.pdf

Basically pure nickel. In the future, it would be good for tacking parts together for oxy/Acetylene brazing.

I also have another bronze alloy filler rod that is supposed to be good for TIG brazing cast iron, but didn't try that one. I'll have to look it up as well...

[steamin10]

Welding cast iron is a real crap shoot. It depends on the grade of cast and the carbon content, and if there is any silicon in the matrix. Results with various alloys and brasses are mixed from good to forgetaboutit. For most attempts I like a nickle iron rod with a bit of preheat, Post heat and slow cooling in sand or other media is helpful at reducing stress between the joint layers.

For Bronze rod to be used I try a spot that is neutral on the part and see if the cast will even wet out. Some castings have so much carbon that it wont bond and just rolls off a dead give away for a dead duck with bronze.

[SteveHGraham]

The part I welded with stainless MIG wire has never had a problem. Shows that it's worth a try when you have nothing to lose.

[BadDog]

My grandfather was a career boilermaker, and we lived in rural N AL, farming from large to small everywhere. He used to do that preheat with high-nickle rod fix quite frequently for our various friends and neighbors. I run along nicely with GMAW, do ok with GTAW (except on thin aluminum), have some limited ability to O/A (weld/braze), but really never did acquire any skill with SMAW. So the filler rod would be my best bet.

[GlennW]

Welding cast iron is a real crap shoot.

$3000.00 German casting...zergut!

[steamin10]

Broken is broken. Our mission is to make it work and live on. Castings are intended to be a reasonable answer for a difficult problem of shape and design size. Once when tearing down a steam traction engine a cross member fractured. Running across the frame rails it required strength and a repair was suspect. It was literally glued back together with Epoxy resin and recast at the foundry. Making a new part was the best option for a nearly 100 year old part.