Akira Takara

Influence of Second Phase Particles on Fracture Toughness in AZ31 Magnesium Alloys

Three kinds of thin AZ31 wrought magnesium alloys sheets were used in order to investigate the influence of the second phase particles on fracture toughness. From the theoretical model, the ratio of λp/dp would be estimated 5~ 6. On the other hand, from the microstructural observation, average particle spacing on each material was sample A: 13.1µm, sample B: 14.1, and sample C: 12 µ. In addition, average particle size on each sample was sample A: 2.1, sample B: 1.9, and sample C: 2.3 µm. Therefore, the ratio of λp/dp calculated from fracture surface observation would be predicted 6 ~ 7. In comparison with the result of the prediction by theoretical analysis was in good agreement with the result of fracture toughness observation. It was found that the variation in plane-strain fracture toughness on AZ31 were affected by both of particle spacing and particle size.

The Forming Process of Magnesium Alloy for Japanese Home Electric Components

Magnesium alloys have replaced resins as a material for the components of electronic products such as cell phone and notebook personal computer mainly, because of their lightness and rigidity. Thin walls, a complicated shape, and high appearance quality are all needed in the external parts. Die-casting and injection molding are the main method of manufacturing magnesium alloy parts. The optimal cast conditions and mold design have been investigated in order that a few defects such as surface cracks and mold cavities in casting parts would be reduced. Instead of cast, plastic forming technologies such as warm drawing and hot forging have been developed to form thinner walls and less defects. Plastic formability of magnesium alloy in hot working is dependent on a grain size of material. The material with fine grains has advantage of being formed at high strain rate. The characteristics of forming processes of magnesium parts for Japanese home electric appliances are compared in the viewpoint of quality, cost, and productivity.