Yes, as an artifact it does automatically work despite it's material. Sort of. In the previous version, at least.
The exact mechanics are unknown (to my knowledge) since the weapon revamps in the latest version, but what it used to be is that everything's effectiveness was expressed in a % based on iron.
Wood/Silver/Other Materials were 50% as effective as a similar item made of iron. A masterful items was 200% more effective than a no-quality iron weapon, and ab artifact was also at least twice as effective (it was a bit muzzy even in the better understood version). So you have 1 (iron, the base value) * .5 (for being a non-weapon material) * 2 (for being artifact) = 1, or just as good as iron. So that lead artifact sword was pretty much just as good as an iron sword (except for the ill-understood artifact bonuses that weren't a straight-up multiplier). So you'd be better off with a no-quality steel sword (1 * 1.2 for steel = 1.2x), or, even better, use that newly legendary weapon smith to make masterful steel weapons (1 * 1.2 for steel * 2 for quality = 2.4x better than no-quality iron), and blow that artifact sword out of the water.
In the new version, we know that bludgeoning weapons are better when heavy (woe to the artifact funmetal hammer forger, for it weighs little, all glory to the gold warhammer of DOOM!), and we know that edge values are actually tracked, so certain metals are better for edges than others, so it's not the simplistic "well, steel is better than iron, so it does 20% more damage, regardless of the weapon" model.
So in answer to your question: We have no bloody idea.