Improving the Tensile Strength Between Pure Al and Low Carbon Steel Joint Fabricated by Friction Welding

In a previous study, the tensile strength of dissimilar friction welded joints that was composed between commercially pure Al (AA1070) and low carbon steel (LCS) decreased with increasing forge pressure. This result was not applicable to the general consequence of friction welding. To prevent a decrease in the tensile strength of joints by the increase in forge pressure, the improving method of tensile strength in friction welding was investigated. Two types of AA1070 with different tensile properties due to tempering condition were used, and the weld faying part of the specimen had various overhang lengths and weld diameters. Dissimilar friction welded joints, which were composed with those AA1070 side specimens and LCS specimens, were made with various forge pressures. Then, the relationship between the tensile strength of the joints and the forge pressure was evaluated. The tensile property of AA1070 base metals with various compression stresses was also investigated, and the result was compared with the tensile strength of joints. The decrease in the tensile strength of the friction welded joints with added high forge pressure, which had an AA1070 base metal fracture, could be prevented by changing of the shape at the weld faying part of the specimen and tempering condition of the AA1070 side. However, such a joint should be made with a suitable forge pressure with the AA1070 side fracture and the same tensile strength as that of its base metal since the consideration of the decrease in the tensile strength of joints by greater forge pressure can be ignored.