Electron Microscopic Characterization of Mechanically Modified Surface Layers of Deep Rolled Steel

Process Signatures describe the relationship between the applied material loads and the resulting surface modification according to the predominant effect of the production process used. This approach is supposed to allow the adjustment of surface layer properties prior to the production process. In this paper, the surface modifications of turned, turned + deep rolled and deep rolled metastable austenitic steel with predominantly thermo-mechanical/ mechanical effects are analyzed by electron microscopic methods like Electron Backscatter Diffraction (EBSD) and Transmission Electron Microscope (TEM) analysis. The modified surface layers show an increase in hardness as a result of the induced Hertzian pressures. TEM investigations of FIB-lamellae cut from the surface zone of the turned/ turned + deep rolled workpiece reveal a nanocrystalline microstructure. A superposition of surface modifications from turning and deep rolling is identified in the turned + deep rolled workpiece.