Not to nit pick, but the complexity of an inverter is not necessary to make the unit operate at 110 or 220. Just an additional tap on the primary transformer that uses 1/2 the windings will allow the same unit to run on either 110 or 220, very simple and very cheap.
But even if the unit is switchable assuming the welder requires some where near the 50 Amp rating of that particular plug in the photo it would require double the current to run it at 110v and you could never do it on a standard household 15 or 20 amp circuit.