High strength steels cover a broad spectrum of applications and are being increasingly used in different areas due to their distinguished features, namely excellent strength-to-weight ratio, good corrosion resistance, deep hardenability, high ductility, high toughness and high strength. These features make them ideal for critical structural applications undergoing severe service conditions and aggressive environments. Long-term durability requires a systematic identification of failure risks and the development of accurate design methodologies. This book covers leading-edge research in these areas. The topics addressed include temperature and stress triaxiality effects on deformation and fracture, analysis of hydrogenation via local electrochemical techniques, second-order direct design methods of columns, hydrogen-steel interactions in automotive transmissions subjected to low-cycle fatigue histories, strain-based design methods for crossing fault rupture in pipelines, metallurgical and technological weldability of quenched and tempered steels, and local-overall interaction buckling phenomena in welded thin-walled columns and beam-columns.