Fig. 1 Schematic of a combined tool with the consumable pin and outer fixed shoulder

Fig. 2 Schematics: a a regularized hole, b geometric dimensions of the pin

Fig. 3 Working principle of the consumable pin in the friction stir remanufacturing: a plunging tage, b repairing stage, c processing stage, d retracting stage

Fig. 4 Surface morphology: a keyhole defect, b repaired joint

Fig. 5 Magnified views of the interfaces using a Pin 1, b Pin 2, c Pin 3, d Pin 4

Fig. 6 Magnified views of interfaces using a Pin 5, b Pin 2, c Pin 6, d Pin 7

Fig. 7 Microstructure of a FSR joint along the repairing direction using Pin 3

Fig. 8 Characteristics of grains in various zones using Pin 3: a P-TMAZ, b QWNZ, c NWNZ, d WNZ, e TMAZ, f HAZ, g BM

Fig. 9 Microhardness distribution along the repairing direction of the joint using Pin 3

Fig. 10 Ultimate tensile strength and elongation of joints: a various conical angles of pins at the top diameter of 3.4 mm, b various top diameters of pins at the conical angle of 14°

Fig. 11 Comparison of joint efficiencies of different techniques [6,7,20]

Fig. 12 Two typical kinds of fractography: a fracture at the interface (mode 1), b fracture at the HAZ (mode 2), c magnified view of the region c, d magnified view of the region d

Fig. 13 Schematics for the material flow of the sound repaired joints: a start of the plunging stage, b end of the plunging stage, c end of the dwelling stage

Fig. 14 Microstructures: a sound joint, interfaces of b the left side, c the right side

Fig. 15 Geometric dimensions of the pin and the regularized hole