Being a rock/heavy metal fan for most of my life, I can say that no, even bands that put out 'satanic' looking artwork or themes are NOT really satanic. Example that comes to mind is Tom Araya from Slayer who puts out albums like these:
but is in fact a devout catholic. It's for show and to satisfy the masses that are into horror and gore and just morbid stuff, but it's no different than whatching a horror movie. It's fiction.
Now, there are bands, hailing specially from Norway, who are messed up and actually ARE Satanist of sorts, but it's a fringe section that is not popular or commercial in anyway. Oh yeah, and the band Chicago is Satanic too! I saw it on the movie 'Little Nicky'
For more info, please watch 'Metal: A headbanger's journey':