Check again, I think you'll find that steel is no where near 1/4" unless someone has replaced it. It will be more like 16 or 18 gauge and now days, it's not even a true steel tube but just a formed square with a few spot welds.
The welds are another story. Do they look like caulk that has been laid down in a smooth bead on top of the metal? Most of the time the welds like like that and have no penetration.
In my own case the bumper simply peeled itself away from the weld in some places and in others, the weld snapped free.