2020 年 5 巻 p. 103-109
The torsion test of 6061-T6 Al alloy friction-welded butt joints was carried out using a self-developed torsion test device. Digital images near the joint interface during torsional loading were captured and displacement distributions were measured by a digital image correlation method (or a DIC method). Local shear strain distributions around the joint were determined and relatively compared with micro-hardness distributions. The test results showed that a sufficient upset pressure was needed for increasing the torsional strength of the friction-welded butt joints. Larger shear strains were generated in a softened region near the joint interface. EBSD analysis revealed that grain sizes at the joint interface were distinctly different from those of the base material. The global shear strains along the gauge length were determined by superimposing respective local shear strains using “the inverse rule of mixtures” for composites and compared with those obtained from a goniometer.
