Before deoxidation, the main inclusions were Fe-Mn-O inclusions in Ti-bearing ultra low-carbon steel melt. After 3 min Al addition, the inclusions changed to be granular and spherical Al 2 O 3 . Al 2 O 3 cluster, composed of granular and spherical particles with diameter 1-2 mm, formed in 7 to 10 min after Al addition into the melt.

The main bottleneck in the catalytic removal of volatile organic compounds (VOCs) is the desire to search for a cheap, highly efficient, and durable catalyst. Herein, we developed a facile synthesis of an ordered mesoporous γ-MnO2 nanostructure (meso-γ-MnO2) by treating an ordered mesoporous Mn2O3 precursor (meso-Mn2O3) with a dilute HNO3 solution, during which the ordered mesoporous framework was well retained. The resultant meso-γ-MnO2 was born with high specific surface area and rich surface oxygen vacancies, which could greatly improve its number of surface active sites and reactivity of surface oxygen species. Surprisingly, the meso-γ-MnO2 exhibited significantly enhanced catalytic activities compared to nonporous α-MnO2 nanorods and γ-MnO2 microurchins, achieving T 90 (the temperatures for 90% conversion of toluene or o-xylene) at 219 and 237 °C for removing toluene and o-xylene under a WHSV of 40,000 mL·g–1·h–1, respectively. Our results provide an effective and facile route to synthesize a highly efficient γ-MnO2 catalyst for VOC removal.

Effects of mold electromagnetic stirring (M-EMS) on the solidification structure of 45# steel billet were investigated by examination of interdendritic corrosion. The results show that the primary and secondary dendrite arm spacings increase from the edge of the billet to the center and decrease obviously with increasing electromagnetic torque, which will be beneficial to refine the solidification structure and enlarge the equiaxed crystal zone. The ratio of equiaxed crystal increases by 15.9% with the electromagnetic torque increasing from 230 to 400 cN·cm. The increase of stirring intensity can improve the cooling rate and the impact of M-EMS on it reduces from the edge of the billet to the central area, where the cooling rates are similar at different torques. The closer to the central area, the less the influence of M-EMS on the cooling rate is. The ratio of the primary to secondary dendrite arm spacing is approximately 2.0, namely, λ 1 ≈2λ 2 , and is constant irrespective of the stirring intensity and position of the billet. Original position analysis (OPA) results indicate that the center segregation of the billet is greatly improved, and the more uniform and compact solidification structure will be obtained with the increase of stirring intensity.

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The existing forms of N and Al in HSLC (high strength low carbon) steel produced by TSCR (thin slab casting and rolling process), the precipitation thermodynamics and kinetics of AlN, and its effects on structure and mechanical property are studied. The experimental results show that only a small quantity of nitrogen is combined into AlN in HSLC steel produced by TSCR and most of the nitrogen in steel is still free nitrogen. Aluminum-nitride is mainly precipitated during the period of slow air cooling after coiling, but not during rolling and water cooling. The acid-soluble aluminum has no obvious effect on the grain size and mechanical property of HSLC steel produced by TSCR whose acid-soluble aluminum content is 0.005% 0.043%. The precipitation of AlN is not the main cause of grain refinement of HSLC steel produced by TSCR, nor is AlN the dominating precipitate that has precipitation strengthening effect. The nano nitrides are not pure AlN, but have complex compositions.thin slab casting and rolling, high strength low carbon steel, AlN, nano nitride, precipitation strengthening