Harden your Power Armor

Harden your Power Armor is an unmarked quest in Fallout.

Detailed walkthrough
Once the Vault Dweller has repaired the hydroponic farms in Adytum, Miles will offer to harden their power armor. After finding one of these rare suits and returning to Adytum, Miles will send the Vault Dweller to the Hub to retrieve a set of chemistry journals.

Ask Mrs. Stapleton (who works in the library located in the Hub Downtown) for the books and then return to Adytum and give Miles the chemistry journals. Miles will then harden the power armor, making it more resistant to all types of damage.