Abstract: A welding method of carrying out an alternating current arc welding by switching polarities of a voltage applied between a wire and workpieces when weld-connecting the workpieces to each other by use of the wire, the workpieces including an aluminum cast material and an aluminum wrought material. In the welding method, the alternating current arc welding is carried out in a way to satisfy |B|/(A+|B|)?0.128 where A denotes an integrated value of an electric current over a time for which the polarity of the wire is positive, and B denotes an integrated value of an electric current over a time for which the polarity of the wire is negative; and thereby an amount of heat input into the aluminum cast material during the welding is set at not more than 67.8 J/mm2.

Abstract: Disclosed is a welding method of carrying out an alternating current arc welding by switching polarities of a voltage applied between a wire 7 and workpieces when weld-connecting the workpieces to each other by use of the wire 7, the workpieces including an aluminum cast material 1 and an aluminum wrought material 3. In the welding method, the alternating current arc welding is carried out in a way to satisfy |B|/(A+|B|)?0.128 where A denotes an integrated value of an electric current over a time for which the polarity of the wire 7 is positive, and B denotes an integrated value of an electric current over a time for which the polarity of the wire 7 is negative; and thereby an amount of heat input into the aluminum cast material 1 during the welding is set at not more than 67.8 J/mm2.

Abstract: The present invention is to manufacture a lightweight high-strength member having desired mechanical properties such as a suspension part of an automobile. The present invention is a method of manufacturing a lightweight high-strength member such as a suspension part of an automobile, and has the steps of pouring the molten metal of an aluminum alloy containing, by weight, 4.0% to 10.5% Si and 0.3% to 1.3% Cu into a mold to cast a preform, and hot-forging the preform by the use of a forging die to form a final formed product.

Abstract: The torsion beam for a suspension is formed of a hollow shaft having a cross section substantially of the shape of an inverted letter U. It, therefore, can be manufactured simply and is enabled to enjoy light weight and improved torsional rigidity. This torsional rigidity can be adjusted and the amount of offset of the joined parts of opposite wheel supporting members from the other component parts can be freely adjusted. The end plates are constructed of a plurality of mutually joined end plates and the torsion beam is joined by welding to the surface for mounting the beam after the end plates have been machined. Thus, the torsion beam type suspension is manufactured with a relatively simple equipment, with the result that cost of equipment and the cost of production are lowered.