Welding an Aluminium casting.

[HobbyCAD]

Hi There all,

I have to do a repair to an aluminium casting, a casing that has some mounting holes in it. Some holes ripped out, and has to be refilled. Cannot use an insert, the hole has been elongated, and cracked out to the side of the casing.

I'm thinking of slotting open the hole from the side, so that it becomes an open channel, to be able to reach all the previously drilled area. The idea is to TIG weld/fill it all up with a filler alloy, machine the surfaces flat to original shape again, postweld solution heat treat and artificially age the casting back to T6 temper, then finally redrill and tap the hole back.

My question is what type of filler alloy to TIG weld fill with. The casting is aluminium 356.2-T6 condition. For that, I assume rods 4043 or 4643 have to be used. 4643 has Magnesium in it, would that not be the better one to use, to get a good bond between the original casting and the new filler alloy material?

Your opinions will be appreciated.

Regards,

Francois

 

[autorotate]

No mater what you do the strength will be comprimised. If the part is critical to safty ide replace it. As far as the right filler your probly best asking someone at a good welding supply shop. If they don know they can probly contact there supply reps thats the best answer i think you can get.

 

[M. Pearce]

HobbyCAD,

You are gonna have to go with a higher alloy rod with more silicon in it.

I just bought some electrodes for my Linc AC/DC cracker box and gonna weld my cast aluminum boat seats brackets in.

When you go to buy your filler rod just ask the dealer and tell them what you are doing.

I don't know the numbers off hand but different brands try to carry their own numbers to confuse us.

The aluminum filler rod you need is kinda stiff due to the alloy-silicon content.

I have a bunch of the stuff in my rod caddy and have become more acustomed to bending them to sort through em.

A 99% aluminum filler rod will bend real easy and it's not for welding your cast.

Consult your supplier for best results.

 

[HobbyCAD]

Hi There Mark,

I've been checking up on this filler rod to use on 356.2 T6 casting aluminium. It seems 4043 and 5356 rods are both not suited for my requirement, as their datasheet indicates their material as non-heat treatable. I have to get the part's temper back to T6 properties by solution heat treatment and artificial aging. It seems the only filler alloy I can find that has specifically been designed for heat treatment, and that will have the same high tensile strength after treatment, is 4643. It also provides a weld of comparable strength to that of the base material.

Hope this is the correct choice of filler rod !!

Regards,

Francois