インサートドライブ摩擦圧接法により接合した角棒継手の機械的性質

抄録

This paper describes the mechanical properties of square section bar welded joint that was made by a center insert drive friction welding method. A center insert drive friction welding method was proposed by authors, which was carried out by the center drive friction welding machine with the center drive gear system. The joint was made up by using a flat disk insert specimen of 10mm or short thickness, and that was inserted to a center gear supported by the drive gears. The material joined was a low carbon steel (same materials) with the weld faying surface shape of 8.9mm square section, and the effect of the friction welding condition on joining phenomena and the joint mechanical properties were investigated. The following conclusions are provided.
(1) Friction torque curve had wear and seizure stages until the initial torque, when the base metals were welded at high friction speed and low friction pressure, i.e. 27.5s^-1 and 36MPa. On the other hand, when the base metals were welded under high friction speed and high friction pressure conditions, i.e. 27.5s^-1 and 90MPa, almost no wear existed until the initial torque was reached. The friction torque rapidly increased and reached the initial peak immediately after the weld faying surfaces contacted each other.
(2) The joint that was made by using the disk insert specimen under a friction pressure of 36MPa and a friction time of 1.6s, or a friction pressure of 90MPa and a friction time of 0.6 to 1.5s, had the same tensile strength as the base metal, and fractured in the base metal. Those joints had a notch defect at the corner part in the adjacent region of the welded interfaces although the joints had also 90 degrees bend ductility.
(3) When the joint was made by using the disk insert specimen under a friction pressure of 36MPa, a friction time of 1.6s and a forge pressure of 90MPa, it had a notch defect at the corner part in the adjacent region of the welded interfaces. Also, when the joint was made under a friction pressure of 36MPa, a friction time of 1.6s and a forge pressure of 36MPa with by using the convex type insert specimen, it had a notch defect. However, a notch defect of those joints were less in comparison with the joint, it was made under a friction pressure of 36MPa and a friction time of 1.6s with a flat disk insert specimen.
(4) The friction welded joint with less notch defect at the corner part in the adjacent region of the welded interfaces was able to make with using a convex type insert specimen and adding forge pressure of 180MPa. The adjacent region of the welded interfaces will be able to make with using a convex type insert specimen and adding higher forge pressure.