A crystal plasticity FE analysis is conducted to understand the fatigue phenomena subjected to cyclic stresses. For simplicity, the crystal plasticity model assumes an isotropic hardening/softening and an isotopic elasticity. The effects of inclusions with the varieties of positions and mechanical properties on the initiation and accumulation of local-plastic strain at the stress level lower than the dominant yielding stress state, i.e macroscopically elastic condition, are discussed in detail.
In order to verify the concept of “excess shear modulus” in steel, experiment of measuring shear modulus during phase transformation and first principal calculation of shear modulus were presented. The experimental results supported the concept of “excess shear energy” and its relation to martensitic transformation. The first principle calculation of Bain curve clearly showed the large effect of carbon on the shear modulus of steel.
This paper describes the mechanism of Sn whisker growth in the welding leads of aluminum electrolytic condenser. Such whiskers are crystalline, have lengths of several microns to several millimeters, and can occasionally result in device failure. The leads used for aluminum electrolytic condensers are composed of Sn- and Cu-plated Fe and Al wire by arc-stud welding. Observations have shown that the Sn whiskers grow in Al-Sn alloy regions at the welding point, where a three-dimension network of Sn exists as a result of rapid solidification from the melt in Al-Sn alloy. This network is microstructure of rapidly solidified from the melt. This one for the most part is occluded by Al, and has slightly opening to surface. It is considered that the driving force for whisker formation is the compressive stress that is present in the Sn network as a result of the different shrinkage rates of Al and Sn during solidification.