This study reports the significantly enhanced aluminizing behaviors of a low carbon steel at temperatures far below the austenitizing temperature,with a nanostructured surface layer produced by surface mechanical attrition treatment(SMAT).A much thicker iron aluminide compound layer with a much enhanced growth kinetics of η-Fe2Al5 in the SMAT sample has been observed relative to the coarse-grained steel sample.Compared to the coarse-grained sample,a weakened texture is formed in the aluminide layer in the SMAT sample.The aluminizing kinetics is analyzed in terms of promoted diffusivity and nucleation frequency in the nanostructured surface layer.
By means of dynamic plastic deformation (DPD) followed by thermal annealing, a mixed structure of micro-sized austenite grains embedded with nano-scale twin bundles (of about 20% in volume) has been synthesized in a 316L stainless steel (SS). Such a 316L SS sample exhibits a tensile strength as high as 1001 MPa and an elongation-to-failure of about 23%. The much elevated strength originates from the presence of a considerable number of strengthening nano-twin bundles, while the ductility from the recrystallized grains. The superior strength-ductility combination achieved in the nano-twins-strengthened austenite steel demonstrates a novel approach for optimizing the mechanical properties in engineering materials.
G.Z. Liu, N.R. Tao and K. Lu Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China
