The song "Iron Man" is not connected to the character of the same name. The Black Sabbath track is the story of a time traveler who sees the future destruction of mankind and when, on his return, he is turned into steel by a magnetic field and his warning ignored, he takes revenge, paradoxically causing the destruction he has seen. However, in the film novelizationTony Stark baptizes his alter-ego "Iron Man" because it is his favorite song.
In The Avengers, Tony Stark wears a T-shirt from the band's Never Say Die tour in 1978. This tour was noteworthy for being the final one to feature Ozzy Osbourne (before he returned years later), and it featured a then-up-and-coming young band called Van Halen as the opening act.