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The effect of reducing the thinning rate when flow forming AZ31B magnesium alloy barrels on the microstructure, crystal orientation, micro-, nano- and macro-mechanical properties was investigated. The results demonstrate that when the magnesium alloy undergoes different degrees of plastic deformation after flow forming, the grain size and dislocation density inside the crystal change greatly, and the evolution pattern of the organization has a significant effect on the mechanical properties of the materials. The stress-strain curve of the cylindrical parts was obtained by nano-indentation and hardness. This is important to improve the mechanical properties of the magnesium alloy.

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An ER430LNb ferritic stainless steel wire was used for a gas metal arc welding (GMAW) test. The characteristics of droplet transfer and its corresponding voltage and current waveforms were investigated using a high-speed camera and synchronous acquisition of electrical signals. The weld formation, droplet transfer patterns and corresponding microstructures under different welding parameters were observed, and the effect of the current level on the droplet transfer frequency was discussed. As the results show, there were three typical metal transfer patterns during the GMAW using the ER430LNb ferritic stainless steel wire, namely short circuit transfer, mix transfer and spray transfer. With an increase in the welding current, the weld formation is changing constantly, and the droplet transfer frequency increases exponentially. With the change in the transfer pattern, the columnar ferrite structure of the weld is continuously coarsening. In addition, hardness measurements were taken on joints welded at different welding currents for comparison.