| Abstract Scope |
The growth potential in the 21st century, which has been projected as the century of materials, will be determined by developing advanced materials through novel processing routes. To overcome issues in steel making, processing, welding, fabrication, etc. associated with higher alloying additions, the present investigation has focused on designing novel lean alloy steel compositions (total alloying <5%, carbon equivalent <0.6) and utilization of energy-efficient quench and partitioning (Q&P) to overcome the strength-ductility-toughness trade-off. A comprehensive microstructure engineering is performed by a systematic variation of alloying elements and processing schedules, thereby, understanding their effect on mechanical behavior. This has led to the identification of a multiphase nano-sized microstructure containing martensite, retained austenite, bainite, and carbides with optimized size, composition, morphology, distribution, etc. Therefore, achieved ultrahigh strength (2000 MPa) combined with sufficient ductility (>10%), Charpy impact toughness (40 J at RT), and fracture toughness (80 MPam1/2). |