1. Steel with a surface that is much harder than the interior metal

Type of: steel

• accustomed
• ace
• archenteron
• archeo-
• archeobacteria
• archeologic
• archeological
• archeological remains
• archeological site
• archeologist
• archeology
• archeopteryx
• archeozoic
• Archeozoic eon
• archepiscopal
• archer
• archerfish
• archery
• Arches National Park
• archespore
• archesporial
• archesporium
• archetypal
• archetype
• archetypical