異種金属材料スポット溶接継手の強度特性評価

（Fe-Cuの接合面解析）

抄録

Recently, weight reduction of vehicles has been advanced to improve the fuel efficiency. It is necessary to use not only steel but also various kinds of materials in order to reduce weight. Therefore, we need to apply methods to join different materials. So, we focused on spot welding, which is the most frequently used joining method in automobile production lines. Strength analysis of dissimilar spot welding using stainless steel and copper is conducted. We use SUS304 and C1100 as test pieces. After spot welding, we observe the cross section using an optical microscope and scanning electron microscope. Also, the temperature distribution of the cross section is calculated using finite element simulation software "ANSYS". In addition, a tensile shear test is also conducted. Heat is mainly generated not in the contact surface but in the steel. Also, as the current is increased, the heat generation increases too. As the base material softens by the heat, the deformation by electrode force also increases. Some parts of the contact surface are melted. In addition, atomic diffusion can be observed under all current. Moreover, the strength improves and stabilizes as the current is increased. The reason of heat concentration in the steel is large electrical resistance of the steel. Also, as temperature becomes higher, base materials are easy to deform because of characteristics of Young's modulus. Dissimilar spot welding of SUS304 and C1100 can be joined by melting, diffusion and deformation on the contact surface.