Some 15 iron tools from the Roman forts Zugmantel and Feldberg (now in the Saalburg Museum, Bad Homburg) were studied metallographically. Of these 15 tools 19 samples were examined at x40 to x500 magnifications. In some cases SEM examination was carried out additionally to study slag inclusions or specific metallurgical structures. The hardness was also measured at the samples level and is given in DPH (diamond pyrimid hardness) in the investigation results. Two different techniques were used to harden 12 of the items: 1) hammer-welding of carburized sheet (steel); 2) surface carburization and quelching of the whole object or special parts of it, e.g., edges. The Roman blacksmith was able to harden his tools to different intensities as necessary for the specific tool. The examinations gave evidence of a sophisticated metallurgical tradition beginning in the early 1st millennium BC.