“Married to Metal” was considered as a working title for Metallica's The Black Album.
The phrase arose as a running joke connected with divorces involving Kirk Hammett, Lars Ulrich, and Jason Newsted during the album's production. The band ultimately decided that the joke should not become the official title.
Other possibilities were discussed, including “Five,” reflecting the record's position as Metallica's fifth studio album, and the title of one of its songs. The musicians eventually selected the eponymous title Metallica because they wanted to keep the presentation simple.
The nickname The Black Album was not the official title. It came from the minimalist cover, which placed a dark Metallica logo and a coiled snake against a black background. The nickname became so widespread that it is now often more recognizable than the formal title.