Welding A356-T6 Aluminum

[GerryR]

Has anyone welded this type of Al and if so, what filler and anything special to consider when welding?

[SundownIII]

Gerry,

My references show 4043 as the recommended filler for this base material. Also shows 5356 as being acceptable, and would have to be used if the part is going to be anodized post welding.

Little more info on the application would be helpful. Will the finished product be subjected to hi-temp, etc?

Welding will take some of the temper out of the aluminum but not sure how that may affect your desired results.

[Portable Welder]

I would not recommend the 4043 for T-6 aluminum.

5356 would be the better choice.

[Old Sporty]

As SundownIII stated, 4043 is fine for T-6. That is what I weld all my 6061-T6 with.

According to "The Procedure Handbook of Arc Welding", 5356 is not one of the recommended fillers for A356. 4043 is the preferred filler. ER4047 may also be used.

While this is what is recomended, I would bet that plenty of A356 has been welded with 5356. I wouldn't know what the results were, however.

[SundownIII]

I weld a lot of 6061-T6 with 5356 but I also know that the weldment is not going to be subjected to heat. 5356 doesn't like exposure to more than about 165 deg F.

As I said before, kinda hard to recommend a filler with the info provided. I gave (and stated as much) that the "book" recommended 4043.

[GerryR]

The application is for a small cast piece and it would be for repairing small cracks caused by stress. The pieces would need to be refinished and anodized (Type III hardcoat). As the parts are no longer made, the old ones need to be repaired. I've welded 6061 with both 4043 and 5356 with good results. I haven't heard of ER4047 but I will look it up along with it's applications. These pieces do take a shock load so I am concerned about the strength. I guess the only thing to do is give it a try. Thank you for your inputs.

[SundownIII]

Gerry,

Repairing "stress cracks", as you probably already know, can present a whole different set of problems.

5356 is stronger than 4043 and is really the only choice if the part is going to be anodized (4043 will turn black).

Let us know how it turns out. Any chance a new part could be machined? We've got a water jet down here that will get very close and I've got a machinist buddy who's dang good.

[Old Sporty]

Gerry - Please let us know how this turns out. Wish you luck with it.

[GerryR]

Thanks for your inputs. It will take some time to know how this holds up under stress but I'll try to give an update, win or lose.

[ASockwell]

A356 is a modified 356 alloy. I believe 356 has a little higher range of Cu and Fe. A356 has better mechanical properties than 356 (elongation). This is an alloy used for sand casting processes. The T-6 refers to the heat treatment given the castings after they are made. We are an aluminum foundry that uses this alloy and heat treat exclusively. Because it is an alloy developed for sand casting, I assume from this you are repairing a casting.

We have two guys that weld castings all day, every day using Synchrowave 350's, 3/16" 5356 filler, and Argon. Initially, we used 4043 filler, but switched to 5356 because of the discoloration during heat treating.

The biggest issue is the material will probably have some embedded sand and other impurities that will float to the top of the molten metal as you're welding. It's worse than welding structural aluminum where you can usually clean the surface of the material and go to it. We have to stop and clean as we're welding to get a good joint.