Final answer:
In 'The Mandalorian', the metal used to forge new armor for Din Djarin is the fictional Beskar steel, known for its extraordinary strength and resilience.
Step-by-step explanation:
The metal used to create new armor for Din Djarin in the TV series The Mandalorian is called Beskar steel. This fictional metal is highly prized throughout the Star Wars universe for its durability and resistance to damage, even able to withstand direct blaster shots. In the show, Din Djarin's original armor is damaged, and he receives a full set of new armor forged from Beskar steel, which provides him with increased protection and plays a significant role in his character's development.