I'm going to be welding some cast aluminum control arms. I will be adding some 6061 t6 aluminum. What filler rod should I use? Do I need to preheat the control arm prior to welding them?

Regards,
Justin

 

Use 5356. Pre heating is a good idea, for something important like control arms I would do a pass or two without filler in the area you want to weld to bring up all the impurities in the cast Al, grind/sand/cut the impurities out and than have at it with filler.

 

I think Dave pretty much covered it.


Post some pics so we can see the badassery.

 

If you aren't going to heat treat it go with a 4043 rod. It is a little softer and will compliment the properties of the casting. Clean it really good with a stainless brush and acetone.

 

5356 will be stronger as welded than 4043. It also has a much higher shear strength than 4043. I think it's like 120Mpa to 80 Mpa or something around there. 4043 will typically have to be heat treated post weld to gain strenght. 4043 is more resistant to cracking if welded improperly.

Basically just cut a nice big groove and use PLENLTY of filler with the 5356 and you will be golden. If it cracks well cooling just add some more filler.

 

Yeah don't use 4043. A picture of what you are trying to accomplish would be worth a thousand words. Remember, the cleaner you can get the piece, the stronger your weld will be.

 

Why have the weld any stronger than the parent material? So it can crack beside the weld again? What is the arm made of 356? Any idea the heat treat on it? T1, T3, etc? That would make a recommendation easier.

For a cast material 5356 is more likely to crack because of its magnesium content.


Check out this chart:
http://www.alcotec.com/us/en/s...t.pdf

 

Why would the parent material crack beside the weld because the weld was stronger than it? If thats the crack that breaks the finished assembly you should have chosen a different grade of AL or gone a completely different route material wise in the first place. You should also consider it a welding job done right. Welds are almost always stronger than the basemetal btw.

 

i build intake manifolds from stock cores (cast aluminum) and i build the plenums fort them out of 6061 (sheet) and use 4043 for the filler and ive never had any issues with it.

mike