In most occasions, it is not necessary to iron silk sheets unless they have been seriously wrung.
Usually, silk bed cover can return to its former shape after being washed and dried. But if you want your sheets to have a fresh look, iron them carefully when they are not completely dry. Use a cool iron on the non-shiny side of silk sheets.
You are suggested not to iron silk bedding and give your attention to the process of cleaning and drying.