Wellhead assemblies, seal assemblies, and methods of locking down an annulus seal disposed within an annulus between outer and inner wellhead members, are provided. A seal assembly is positioned in an annulus. An energizing member is axially translated downward to energize an annulus seal element and outwardly radially compress a high-strength lockdown member into contact with an inner diameter surface of a wellhead member. The wellhead member can include a set of wickers. During compression, the outer diameter surface of the lockdown member is plastically deformed onto the set of wickers.