A rapid aging treatment method of Al-7Si-0.55Mg alloy using electric pulse, namely electric pulse aging treatment, is explored in this study. The effect of electric pulse assisted aging on microstructure and properties of Al-7Si-0.55Mg alloy are investigated by means of optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), tensile tests and hardness tests. The results show that the microstructure of the Al-7Si-0.55Mg alloy is effectively refined, and the morphology of eutectic Si changes from long and thin strip to a spherical shape or short rod. The elongation of the Al-7Si-0.55Mg alloy is significantly improved after electric pulse assisted aging, albeit it did slightly compromise the tensile strength. It is important to reduce the aging time by 3 h, saving energy. According to classical nucleation theory, the formula of the phase nucleation rate promoted by an electric pulse was determined. The application of an electric pulse can accelerate the nucleation of phase transformation by decreasing the thermodynamic energy barrier, which increases the nucleation rate and significantly improves the properties of the alloy. It provides an experimental and theoretical basis for the Al-7Si-0.55Mg alloy to obtain good mechanical properties and industrial applications.

Retrogression and re-aging (RRA) treatment has been proven to effectively overcome the trade-off between strength and corrosion resistance. Current research focuses on the heating rate, temperature, and holding time of retrogression treatment while ignoring the retrogression cooling ways. In this paper, the effects of RRA treatment with different retrogression cooling ways on the microstructure and properties of newly developed T’/η’ strengthened Al-Zn-Mg-Cu alloys were investigated by performing tests on mechanical properties, intergranular corrosion (IGC) resistance, and electrochemical corrosion behavior. The results show that the mechanical properties of samples subject to RRA treatment with water-quenching retrogression (ultimate tensile strength, yield strength, and elongation of 419.2 MPa, 370.2 MPa, and 15.9, respectively) are better than those of air-cooled and furnace-cooled samples. The corrosion resistance of water-quenching (IGC depth of 162.2 μm, corrosion current density of 0.833 × 10⁻⁵ A/cm²) and furnace-cooled samples (IGC depth of 123.7 μm, corrosion current density of 0.712 × 10⁻⁵ A/cm²) is better than that of air-cooled samples. Microstructure characterization reveals that the effect of the retrogression cooling rate on mechanical properties is related to the size of T’/η’ precipitates with grains as well as the proportion of T’ and η’, while the difference in corrosion resistance depends on the continuity of grain boundary precipitates (GBPs). With mechanical properties, corrosion resistance, and time cost taken into consideration, it is appropriate to select water quenching for retrogression. These findings offer valuable insights for further design to achieve superior performance in various applications.

In order to get practical models, we've made a lot of experiments about thermal analysis on gray cast irons and got various models by means of different mathematical methods these years. It was proved that artificial neural networks (ANNs) were fit for modeling of cast iron quality prediction. Two kinds of BP networks for calculating chemical composition and mechanical properties of gray cast iron were studied. Based on these effective models, we can develop various types of gray cast irons quality testers. In this paper, the basic method of applying ANNs in gray cast iron quality prediction and the results are introduced.

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A new method and a device for fast calculating graphite shape in cast iron in front of the furnace will be introduced in this paper. The new method is named “amplitude and frequency equivalent of bubbles” and its foundation is to blow air into liquid iron and to take the numbers of blowing bubbles and differential pressure inside the bubble as the characteristics and then to obtain the equivalent by which the graphite shape in cast iron can be calculated before casting. The new device depends on the new method mentioned above consists of a heat-resistant and replaceable detector, a microcomputer data acquisition system and an air microcompressor.