The Gleeble-3800 thermal simulator was used to perform hot compression experiments on Q345 steel at a temperature of 1123~1373 K, a strain rate of 0.01~10 s−1, and 60% deformation. Analysis of the flow curves of Q345 steel revealed that flow stress decreases with the increase of deformation temperature and decrease of strain rate. According to the stress–strain curve of Q345 steel, three constitutive models of Johnson–Cook, Modified Johnson–Cook and strain-compensated Arrhenius were established. By comparison, it was found that the strain-compensated Arrhenius model has higher accuracy, and its correlation coefficient and average relative error are 0.995 and 4.93%, respectively. In addition, the thermal processing map of Q345 steel was established, and the optimal processing range was temperature 1253–1373 K, strain rate 0.5–10 s−1.
The surface of Inconel 625, a nickel-base alloy, was strengthened by vacuum electron beam scanning technology. The evolution of its microstructure was analyzed by electron backscatter diffraction (EBSD) and the friction and wear tester (RETC). The results show that the FCC phase in the microstructure of Inconel 625 nickel-base alloy is stripped and islanded after electron beam scanning treatment. The austenite texture type changes and finally forms a typical cubic texture with a certain strength of S texture. With the increase in temperature of the focusing current, the wear resistance of nickel-base alloy plates first increases and then decreases. Under a 720 mA focusing current, the wear volume and wear rate are the lowest, which are 0.141525 mm3 and 1.41525 × /N∙m, respectively. The wear rate decreases by 26.64%, which may be related to the columnar crystals produced in the melting area. After electron beam surface modification, the oxidation wear and adhesive wear are relatively smaller than the original materials.
Inconel 625 nickel-base alloy was modified by electron beam surface alloying (EBSA) with TiC as the coating at different scanning speeds (80 mm/min, 100 mm/min, and 120 mm/min). Its microstructure evolution and friction and wear evolution were characterized using electron backscatter diffraction (EBSD), a microhardness tester, and a friction and wear tester (RTEC). The results indicated that the FCC phase in the microstructure of the Inconel 625 nickel-base alloy is island-shaped after EBSA. At different scanning speeds, the austenitic texture types will eventually form primarily S-texture accompanied by Goss texture and Brass texture of varying strengths. With an increase in scanning speed, the surface hardness of nickel-base alloys decreases. The highest surface hardness was 457 HB at 80 mm/min, and the surface hardness was 1.936 times higher than that of the base material. With an increase in scanning speed, the wear resistance of the nickel-base alloy plates decreased gradually. At the scanning speed of 80 mm/min, the wear volume and wear rate were the lowest, which were 0.9131 mm3 and 3.0437, respectively, and the wear rate decreased by 30.48%.
A layered gradient aluminum foam was prepared by powder sintering with sodium thiosulfate (Na2S2O3) particles as the cell-forming agent. By cutting, polishing and observing under a microscope, it was found that the aluminum powder particles were not completely melted after sintering but were only combined by surface melting. Based on the quasi-static compression test and the macroscopic diagram of the sample during deformation, the mechanical properties of gradient aluminum foam were studied, and their deformation characteristics and mechanism were analyzed and discussed.
In order to study the microstructure evolution and flow stress behavior of as cast antibacterial austenitic stainless steel containing 1.52 wt.% copper, Gleeble 3800 was used for thermal compression simulation test. Through OM and EBSD analysis, it is found that the dynamic recrystallization mechanism of thermal deformation is mainly discontinuous dynamic recrystallization. With the increase of deformation temperature and deformation rate, the proportion of recrystallization nucleation gradually increases. The growth of twins relies on recrystallization and, at the same time, promotes dynamic recrystallization. Considering the influence of strain on flow stress, the strain compensation Arrhenius model is established according to the obtained stress-strain curve, and high accuracy is obtained. The correlation coefficient and average relative absolute error are 0.979 and 7.066% respectively. These results provide basic guidance for the technology of microstructure control and excellent mechanical properties of antibacterial stainless steel.