Aluminum weld keeps cracking

[montyy]

I've been welding steel for a good while now with no issues, but I'm trying to branch into aluminum and every single weld I'm making is cracking either right away or a few hours later. I'm using 4043 filler on 6061 aluminum, TIG setup and I made sure to clean everything with acetone before starting. The welds look well when I finish but then they just crack down the middle.

Is this a heat issue or what? I've watched a bunch of youtube videos and thought I was doing everything right but clearly I'm missing something

 

[welder B0b]

if it's aluminium welds, usually it's cracking because of a combination of hot cracking and improper cleaning, also the technique.
try to use a different filler metal, the one that's more ductile than 4043 for this application, and make sure your cleaning process is thorough by using a dedicated stainless steel brush to remove the oxide layer before welding

 

[Cayle_]

To the best of my knowledge, preheating the aluminum to around 200 to 250°F range before welding sounds counterintuitive but it slows the cooling rate and reduces cracking