2022 年 63 巻 10 号 p. 1337-1344
In this study, friction welding was applied to carbon steel tubes at a high speed condition to achieve an eco-friendly welding process and a superior mechanical performance. Friction welding is a very efficient process for joining materials without defects, especially with joint rods or tubes. For this study, cold drawn carbon steel tubes (AISI 1020) were introduced as the base material and successfully joined by friction welding. Friction welding was performed with parameters of a burn-off length (1, 2 and 5 mm). In order to analyze the welds, the electron backscattering diffraction method was introduced and observed the grain boundary characteristic distributions such as grain size, shape and orientation. To evaluate the relationship between the mechanical properties and microstructure, Vickers microhardness and tensile tests were introduced. As a result, the yield strength of the welds significantly increased relative to the base material at all conditions, and which derived from the microstructure development like a refined acicular ferrite grains through the dynamic recrystallization during the welding. Consequently, we suggest the optimum conditions of the friction welding with the interdependence of the microstructures and mechanical properties in this study. This demonstration substantially offers the possibility of an eco-friendly environment and superior tube welding quality without any defect and harmful gases at the high speed welding process as well as at the lowest cost. This technology can be extended to mass production processes with exceptional benefits for various industries.
