Bimodal Grain Size Distribution Enhances Strength and Ductility Simultaneously in a Low-Carbon Low-Alloy Steel
- PDF / 4,945,807 Bytes
- 10 Pages / 593.972 x 792 pts Page_size
- 53 Downloads / 250 Views
N structural materials, high strength and ductility are often counteracting properties.[1] In a pure metal or an alloy with given composition, the strength can be increased either by work hardening,[2] or by reducing the grain size[3,4] or by applying the two procedures together.[5,6] The methods of large plastic deformation, like equal channel angular pressing (ECAP),[5,6] accumulative roll bonding (ARB),[7,8] or high pressure torsion (HPT)[9] can produce submicron grain size materials with extremely high strength. However, it was generally found that the large strength was accompanied by poor ductility.[10,11] Transmission electron microscopy (TEM)[12–14] and X-ray line profile analysis[15–17] have shown that in the materials processed by these severe plastic deformation (SPD) methods, not only the grain size reduces to submicron values but also the dislocation density increases to large values saturating usually in the range between 1015 and 1016 m2.[15–18] The other procedure which produces a fine grain size along with high dislocation densities in steels is rapid quenching of
PE´TER J. SZABO´, Head of Department, is with the Department of Materials Science and Engineering, Budapest University of Technology and Economics, Budapest, Hungary. DAVID P. FIELD, Professor, is with the School of Mechanical and Materials Engineering, College of Engineering and Architecture, Washington State University, Pullman, WA. BERTALAN JO´NI, PhD Student, is with the Department of Materials Physics, Eo¨tvo¨s University Budapest, Budapest, Hungary. JELENA HORKY, PhD Student, is with the Physics of Nanostructured Materials, Faculty of Physics, University of Vienna, Vienna, Austria. TAMA´S UNGA´R, Professor Emeritus, is with the Department of Materials Physics, Eo¨tvo¨s University Budapest, and also with the Department of Physics and Materials Science, City University of Hong Kong, Kowloon, Hong Kong. Contact e-mail: [email protected] Manuscript submitted July 6, 2014. METALLURGICAL AND MATERIALS TRANSACTIONS A
low-alloy steels from the austenitizing temperature.[19] Ductility along with high strength in low-alloy, lowcarbon ferritic sheet materials was achieved by quenching austenite to room temperature followed by cold rolling and annealing.[20] The microstructure was characterized by optical and electron microscopy and mechanical testing. Submicron grain size with different grain size distributions was found to give good strength and acceptable ductility. Somewhat similar results were obtained on a similar low-alloy, low-carbon ferritic steel by quenching into brine-water followed by cold rolling and annealing between 773 K and 873 K (500 C and 600 C).[21] The grain size distribution was determined by scanning electron microscopy (SEM). In the present work, we report on the thermomechanical treatment of a low-carbon low-alloy steel. The quenching, cold rolling, and annealing conditions are in the similar range as in the works of References 20 and 21. The grain size and grain size distribution are determined by SEM. The total an
Data Loading...
