STUDIES OF DAMASCUS STEEL BLADES .2. DESTRUCTION AND REFORMATION OF THE PATTERN

Two genuine Damascus steel blades and two reconstructed Damascus blades have been austenitized to the point where all of the cementite particles responsible for their Damask pattern were dissolved into the austenite. It is demonstrated that subsequent thermal cycling causes the reprecipitation of cementite particles in the same sheetlike morphology of the original blades, provided that the austenitization temperature is low enough to avoid homogenization of the major impurity elements, Mn, Si, S, and P. The results provide strong support for the hypothesis of Part I [Materials Characterization 30:175-186 (1993)], that the formation of sheets of clustered cementite particles in genuine Damascus blades is a type of carbide banding caused by microsegregated third elements deformed into sheets during the cyclic forging process. Several thermal cycling experiments on reconstructed blade pieces are presented. The experiments support a model in which the third-element additions bias the nucleation of cementite particles into the sheet geometry, followed by enhancement of the sheet morphology by particle coarsening during the thermal cycles.