u/Interesting-Owl7490

Hey guys, I bought a mig welder and set it up for aluminum a few days ago, this was my first time ever welding in my life, i am welding 6061 aluminum 1/8 thick tubing with 5356 .035 wire, with a bit of preheating. My question is, do these welds look strong? Like good enough to be used for a tube frame for like a dune buggy or something, and what should I improve on, thank you!