Fe-Cr alloys with different chromium contents have been designed in the current study for the ball mill liner working in weakly alkaline slurry. The structure, mechanical properties, corrosion behavior and erosion-corrosion behavior of the alloys were investigated. The result shows that with the increasing Cr content, the hardness and corrosion resistance of the alloy are improved. However, the impact toughness of the alloy shows a decreasing trend with the increase of Cr content. The alloy with the Cr content of 6.978 wt% exhibits the best erosion-corrosion resistance among all alloys in the weakly alkaline slurry. Further analysis shows that the erosion-corrosion mass loss of these alloys in weakly alkaline slurry mainly results from pure mechanical erosion and the interaction between corrosion and erosion. The damage process has also been discussed by interaction models of corrosion and erosion. The result is beneficial to provide reference for selection and development of erosion-corrosion resistant material for ball mill liner working in weakly alkaline medium.
Under compressive testing at 400 °C and a strain rate range of 0.05–5 s−1, the hot deformation behavior and microstructure evolution of an as-cast (AC), as-extruded (with a bimodal grain structure (named as Ex-1) or a relatively uniform fine grain structure (Ex-2)) WE43 alloy have been investigated and compared. The results indicate that the AC sample exhibits the highest peak stress, while the Ex-2 sample has the lowest value. Within the AC material, fine grains were firstly formed along the pancake-like deformed grains (as a necklace structure). The necklace structure was also formed within the Ex-1 and Ex-2 materials at high strain rates of 0.5 and 5 s−1. However, a lamellar structure that the coarse elongated grains divided by parallel boundaries was formed within the Ex-1 material. A relatively more homogeneous fine grain structure is achieved after a true strain of 1.0 within the Ex-2 material at a low strain rate of 0.05 s−1. In addition, a discontinuous dynamic recrystallization mechanism by grain boundary bulging is found to occur. After a true strain of 1.2, a (0001) fiber texture, a typical rare earth (RE) texture, and a relatively random texture are formed within the AC, Ex-1, and Ex-2 WE43 alloy material, respectively.
This study examined the oxidation properties of rare earth steel at high temperatures (600 °C–900 °C) in the air atmosphere by using Scanning Electronic Microscope (SEM) with an energy dispersive spectroscopy (EDS), x-ray diffraction analyzer (XRD) and atomic force microscopy (AFM) analysis method. High temperature oxidation experiment showed that rare earth element Ce played a very good antioxidant effect with the increasing oxidation temperature. After continuous oxidation at 600 °C, 700 °C, 800 °C and 900 °C for 150 h, the mass gain of the rare earth steel were 1.25 mg cm−2, 2.41 mg cm−2, 12.34 mg cm−2, and 13.37 mg cm−2, respectively. In comparison, the matrix steel under the same conditions were 1.31 mg cm−2, 2.94 mg cm−2, 13.98 mg cm−2, and 15.63 mg cm−2, respectively. AFM features of the oxidized surface confirmed that the rare earth element Ce could inhibit the growth rate of the oxide in the early stage of oxidation, and preferentially promote the formation of the spinel oxide. The surface-dense spinel oxide (Fe, Cr, Ni, Mn)3O4, the enrichment of Cr-containing layer in the middle, and the formation of the Si-rich oxide in the inner layer all affected the high-temperature oxidation resistance of the rare earth steel.
In this study, Ti particles reinforced Mg AZ31/Al 6082 composite sheets were successfully prepared by hot rolling, with the aim of revealing the effect of Ti particles addition on the mechanical behavior and microstructure of Mg AZ31/Al 6082 composite sheets. The results showed that Ti particles were uniformly distributed at the interface of the Mg/Al-Ti composite sheets, which could greatly reduce the amount of Mg-Al intermetallic compounds during annealing treatment. Compared to the Mg/Al sheet, the tensile strength and elongation of the Mg/Al-Ti sheet could be improved simultaneously after the annealing treatment. Ti particles addition hardly affected the grain size, texture type, and tensile fracture morphology of the Mg layer and Al layer in the composite sheets before and after annealing. This present study provides a new perspective on the mechanical behavior and microstructure of Mg/Al composites through the addition of metal particles.
Internal electromagnetic stirring is an advanced melt treatment method, which can be used in direct chill casting to prepare large-scale Al alloy billets. Intercooling intensity is a primary parameter of internal electromagnetic stirring; its effects on temperature fields and microstructures have been investigated via numerical simulations and industrial experiments, respectively. The simulated results show an increase in the intercooling affected area and a decrease in sump depth with an increase in the intercooling heat transfer coefficient. The heat transfer coefficient should not exceed 500 W/(m2 °C) because the solid fraction of the intercooling end bottom may exceed 50%. The experiment’s results demonstrate that the average grain sizes in the edge, 1/2 radius, and center are 151 ± 13 μm, 159 ± 14 μm, and 149 ± 16 μm, respectively, under a liquid nitrogen flow rate of 160 L/min, which is much finer than that of 80 L/min and more homogeneous than that of 240 L/min. Furthermore, an experimental liquid nitrogen flow rate of 80 L/min, 160 L/min, and 240 L/min approximately correspond to the simulated heat transfer coefficient of 200 W/(m2 °C), 300 W/(m2 °C), and 400 W/(m2 °C), respectively.