brazing axle tubes

[5-90]

Right you want to slow the cooling rate so the filler metal can fill all the voids as it cools with no cracking and avoid getting brittle.

That, and slowing the cooling inhibits realignment of the microstructure. Not totally - you'll need a heat-controlled oven and about hours for that - but enough to keep things under control.

You're otherwise spot-on - have you taken courses in metallurgy and materials, or are you self-taught?

 

[Weasel]

That, and slowing the cooling inhibits realignment of the microstructure. Not totally - you'll need a heat-controlled oven and about hours for that - but enough to keep things under control.

You're otherwise spot-on - have you taken courses in metallurgy and materials, or are you self-taught?

ME by degree. Did have a semester in a pretty decent welding class, the rest is mostly self taught.

 

[5-90]

ME by degree. Did have a semester in a pretty decent welding class, the rest is mostly self taught.

You sound like it. I've got to get a few things pointed back in the right direction, then I'd like to finish my Tool & Die Maker and BS/MET (otherwise, I'm largely self-taught.)

 

[fxdlrider]

I had a chat with my father-in-law. He was a welder for about 15 years or so, and he suggested the nickel rod as well. One thing he also mentioned was to weld 1/2 inch and peen the weld until it cooled. Rotate 180 degrees and repeat. He said the peening of the nickel helped to make up the difference in expansion rates. He said that was the way the old timer taught me and I never questioned it.

 

[5-90]

I had a chat with my father-in-law. He was a welder for about 15 years or so, and he suggested the nickel rod as well. One thing he also mentioned was to weld 1/2 inch and peen the weld until it cooled. Rotate 180 degrees and repeat. He said the peening of the nickel helped to make up the difference in expansion rates. He said that was the way the old timer taught me and I never questioned it.

Peening a hot weld is a variation on forging - and with a high-nickel fill metal, can be very useful. I'd still pre- and post-heat the casting, but peening is a good help for if you're not sure about penetration (with room in between the parts. Otherwise, you're trying to "forge weld" them together - and you can still get a strong weld, if the base weldment is solid.)

 

[vetteboy]

The peening also acts as a stress-relieving method. It helps all those little molecules get their collective asses straightened out. Basically, if stresses start to build from unequal cooling and contraction rates, peening can help distribute them throughout the whole weldment instead of in a localized area.

 

[fxdlrider]

Sorry, I guess I could have been a bit more specific. Yes he also said to preheat and post-heat as well. One method he suggested for cooling was to heat some sand to 400 or so degrees in the oven, and when you are done welding, you place the part in the sand and let the whole thing cool. I would have to make some type of container to place the axle tube/housing in, but that would be a very steady, slow method for controlled cooling.

 

[5-90]

Sorry, I guess I could have been a bit more specific. Yes he also said to preheat and post-heat as well. One method he suggested for cooling was to heat some sand to 400 or so degrees in the oven, and when you are done welding, you place the part in the sand and let the whole thing cool. I would have to make some type of container to place the axle tube/housing in, but that would be a very steady, slow method for controlled cooling.

Yes, it would - apart from a heat-controlled oven, that's about best. Be sure to have enough sand to pack and fill, tho...

 

[53guy]

I work on aircraft as well and I can tell you that brazing is an old school method and that there are better ways to join two metals out there today. TIG being one of the better choices. All our engine componets (jet engines) are tig'ed and anything that's not rivited is tig'ed.

 

[Weasel]

I think the sand deal is going a bit overboard. Plenty of people have done it with just pre/post heating and been fine.

 

[Gecko321]

when i put the8.8 into my xj, we just cleaned the aera between the tube ad the center section and made 2 passes with a 7018 rod. no pre/post heating. i have been beating and bashing on it for about 2 years with the gears weled up. never once had anytype of problem. we check all the weld about twice a year as a matinence regimine.

mike

 

[falcon556]

From the discussion it is pretty obvious that the tubes are regular steel and the center is cast. Is this a common practice with other axles as well such as Dana 30, 35, 44?

 

[RCP Phx]

From the discussion it is pretty obvious that the tubes are regular steel and the center is cast. Is this a common practice with other axles as well such as Dana 30, 35, 44?

Yes,with some exceptions like Ford 9" and Toyota that have all steel 1-peice housings!

 

[xjbubba]

Lincoln Electrics' web site contains a good guide to welding cast. They indicate NO pre-post heating is also acceptable:
http://www.lincolnelectric.com/knowledge/articles/content/castironpreheat.asp

"To Heat, or not to Heat

In general, it is preferred to weld cast iron with preheat--and lots of it. But, another way to successfully weld cast iron is to keep it cool--not cold, but cool. Below, both methods will be described. However, once you select a method, stick with it. Keep it hot, or keep it cool, but don't change horses in the middle of the stream!---"

The only time I welded cast (re-oriented the down tube on an exhaust manifold) I used arc and nickle rod, with pre-heat, ~1 or so inches of weld, peen, post heat. Then repeated until finished. Lincoln's "cold" method may be usefull for welding the tubes to the center section if you don't want to tear the diff apart.

 

[FordGuy]

I have always Arc welded them with a high nickel rod.