Check your welding penetration.

So if u a hobby welder its worth doing this to see just how real your welds are.

Cut a cross section, polish and dab a bit of Naval Jelly rust remover on the cross section
It will show up your fillets and you can see how well you penetrating the steel when you weld.
Here is welds on my prototype bracket.
For picture purposes I have tried to trace what naval jelly showed up.
not good at all if you look at the gap. But 1/4" steel is at limit for my machine.

Can you grind a V to help get you weld down into it with a root pass? Then make a couple more passes to finish it.

Did you grind a bevel on the edge, doesn't look like it.

That is one of the issues with mig it is real easy to get really pretty looking bad welds. So you are wise to do the penetration check. And you don't really need the navel jelly the gap in the center tells the story.

My old roommate got his welding certifications. They had him well pieces together and would slice them to show the penetration. He had a sets of different thicknesses that were good welds and had written down the machine settings on them for reference laying around our garage/shop.

Garry Foster said:

That is one of the issues with mig it is real easy to get really pretty looking bad welds. So you are wise to do the penetration check. And you don't really need the navel jelly the gap in the center tells the story.

Click to expand...

You so correct Gary, I saw this idea/technique on youtube with Jody of Welding Tips and Tricks. Very cool experienced guy and he pointed out this to be an issue with Mig welding as you say.

In this specific case, these welds will work fine, its not life threatening only workbench brackets, but were this a road going heavy load bearing trailer as many do weld their own trailers, i would be concerned.