Intro and layin' some newbie beads

[DWSD]

Hey, Doug, a new 250EX owner here. In maybe 10 to 15 hours of total torch time, I've burned through about 1 150 cuft tank of Argon learning with the new machine. I have been MIG welding for about 20 years, but as a hobbyist. I'm decent with it, but not a professional, daily user. I might have the equivalent of 6 to 9 months of daily use on the MIG. From my MIG welding, I have a decent handle on the concept of penetration and puddle management. It seems TIG is changing the way I think about MIG welding, which is kind of a bonus.

Anyhow, I've been experimenting with the settings and different materials. Thought I'd solicit some feedback.

The mild steel are some beads I ran on 1/8" 3x3 square tubing, just for practice. I used very little filler, mostly the beads are coming from low speed pulse. Is that why the beads themselves are a bit concave? I did grind the finish pretty clean before welding, but there was a bit of pitting remaining. Suspect that might have contaminated the weld a bit? Is it acceptable to weld with little to no filler or am I compromising weld strength?

The pulse settings come, more or less, from Jody at weldingtipsandtricks.com On the mild steel, the heat was about 200A, but 35% background current and 35% peak. Pulse fhz = about 1 . Without pulse, I would have used about 125A and adjusted the puddle with the pedal.

I've also posted a picture of some some AL practice. You can see where I dipped the tungsten and fouled things up pretty good once or twice. Bear in mind the AL box I made and then I've been adding the practice beads over the last month or so. Some beads I'm more proud of and some less. The corner beads on the box are oldest, as I first fabbed up the box 1/8" x 2" AL stock. It is about 5" x 2" x 2" Also, some are much more recent as my skills have been (somewhat) improved in terms of uniformity.

I'm thinking much of it seems overheated, I think with the grainy surface texture. Is that right?

Thank you,

Doug