In the current Prime Earth continuity, Kerenthium Steel was purported to be the strongest metal in the universe, but was broken by Superman. Interestingly, in Superman #365, Superman himself describes it as the ' densest' metal known, so it's apparently both the densest and strongest. ACCESS: Whoa--nice job! Wonderful, even! And that's one tough length of lariat you got there! What is it--Adamantium?

What is the strongest metal in the DC universe? - Science

VERNON QUESTOR: Promethium-coated metal... creating a virtually indestructible car to eliminate accidents. Honourable mention #2 goes to Marvelium, created by Captain Marvel in Captain Marvel Adventures #100. Much like Supermanium, it's created by crushing other elements to make the ' heaviest and strongest element of all'. Superman (in World's Finest #41) creates a new element by applying heat and pressure to an ore. It's named Supermanium in his honour and is described as ' the hardest substance in existence'. POSEIDON: Those trinkets were once part of Zeus' mighty Aegis itself... the impenetrable shield formed from the hide of the Great Goat Amaltheia, who wet-nursed the infant Zeus and thus provided the energy from which Olympus sprung. Only two beings were ever able to violate the power of the Aegis. The history behind the Bracelets of Submission was developed by William Moulton Marston, who created Wonder Woman, and the bracelets themselves actually had real-life counterpart: Marston's lover Olive Byrne – upon whom much of Wonder Woman's original character was based – frequently wore bracelets that directly inspired the Bracelets of Submission. [11]

Additionally, Promethium was introduced late in the Pre-Crisis era, but also exists in the later Post-Crisis continuity, and the current Prime Earth continuity as well. ACCESS: Indestructible metal. Doesn't exist in your universe--but you've got Promethium, so it kind of evens out.

Bracelets of Submission | DC Database | Fandom

In some parallel worlds, but not others, the bracelets are the key to Wonder Woman's main weakness.

There are several metals which have been described as unbreakable, indestructible, or the hardest or strongest in the DCU at one time or another.