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post #1 of (permalink) Old 03-20-2001, 02:11 AM
**DONOTDELETE**
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Welding Axles and metal types

I was looking at this welding site
http://www.twi.co.uk/bestprac/jobknol/jk25.html
http://www.twi.co.uk/bestprac/jobknol/jk19.html
and it was talking about all the different types of casting metals and pre heating and hydrogen cracking and all the stuff I'm just starting to learn about.
Anyway, that got me thinking about what type of cast metal is used in the yokes and housing of D44's. I read somewhere that the D60 has a Nodular housing but not the D44's.
Does anyone know what type of cast metal is used in the yokes and housing of a D44? I'm assuming the yokes are cast and not some kind of forging.
A number of people with the scout axles have ground out the welds on the yokes and twisted more caster in and then re-welded using the low hydrogen rods, 7018 I think. They didn't have to pre-heat or anything to keep them from cracking, are they just lucky or is it a special cast metal which resistes cracking. Does anyone know how Dana welds this stuff in their factory? Stick, TIG, MIG? Do they pre-heat?

Also, a couple other questions for you welding experts out there.
Which has the lower Hydrogen, stick using the 7018 rod, or MIG?
There has been some talk about getting good penetration, does the "more is better rule" apply to welding on cast metals as well? If you turn up the power to get better penetration are you more likely to have the metal crack?

Anybody with knowledge, please share, Thanks, Max

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post #2 of (permalink) Old 03-20-2001, 10:01 AM
jeepfiend
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Re: Welding Axles and metal types

I don't know about the differences in the metallurgy between the 44 and the 60, but I will take a stab at a couple of the other items. I think most diff housings are a maleable cast. With the abuse that the housings take, rocks, etc. it would make sense to have them be a little less brittle. Looking at the welds, and knowing what little I do about production, I would guess that they are wire welds.
As far as the hydrogen differences, I will ask our QC guy and get back to you on that one.
Without a preheat, deeper penetration can cause cracks. Often the cracks are the result of lamilar tearingm i.e., one of the constituents in the weld cools faster than the other, and the resulting contraction causes the weld to tear away from the surrounding material. If you are really burning it in, it is always a good idea to preheat. The heat doesn't have to be anything extreme, but the area surrounding the weld needs to be hot so it will cool more evenly. I have just used a rose-bud tip on the torch, or I have even heated pieces in the oven for a couple of hours. A thought just occured to me about the D44 housing. I have one on the front of my old chevy 4x4, and it has some nasty gouges in the bottom, and even one of the stiffeners is bent. This is not indicative of a non-maleable cast. Non-maleable cast is what is called an uneven material, meaning that it's properties are not the same in all directions. Cast behaves very well under compression, but it is not nearly as strong in tension. Where maleable casts do better in tension, and are also ok in compression. Due to the forces that a housing sees, I would definitely guess that they are all some type of maleable cast. If anybody knows more, I am interested to know also, as I am getting ready to build axles for my CJ5.
We're in luck, the QC guy just stepped into my office. E70 wire doesn't have any hydrogen issues associated with it. And E71 flux core is also equivalent to E7018. The point was also made that you can get hydrogen induced cracking with low hydrogen electrode if you don't take proper care of your rod. In most applications we weld, cracking will be a result of poor heat control. Too much too fast will almost always lead to cracking.
I would also think that the yokes could be a forging, and not a casting.
As far as welding these things, if you need a lot of weld, I would always multipass, and keep the heat input low.

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Jeepfiend
All my Jeeps are in pieces!
post #3 of (permalink) Old 03-20-2001, 10:09 AM
jeepfiend
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Re: Welding Axles and metal types

Just a quick thought, I just looked at the links in the posting, and they talk a lot about the HAZ (heat affected zone) this has a lot to do with what I talked about above and controlling your heat input. If you are concerned about welding these things, go to a scrap yard or a salvage yard, and see if they have any items you can get for scrap price to practice on.

Cage Up, Wheels Down
Jeepfiend
All my Jeeps are in pieces!
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