Abstract: To adopt die casts product as parts of a vehicle body frame. A vehicle body frame is provide with an alumite treating, showing that brightness and appearance of pivot plates which are die cast products differ from those of non-die cast products, head pipes, longitudinal pipes and cross pipe. By carrying out a local coating treatment on the pivot plates, the pivot plates are provided with a color the same as that of the pipe, the longitudinal pipes and the cross pipe. By making die cast products portion of constituent parts, the fabrication cost of the vehicle body frame can be reduced.

Abstract: To adopt die cast products as parts of a vehicle body frame. A vehicle body frame is provided with an alumite treating, showing that brightness and appearance of pivot plates which are die cast products differ from those of non-die cast products, head pipes, longitudinal pipes and cross pipe. By carrying out a local coating treatment on the pivot plates, the pivot plates are provided with a color the same as that of the head pipe, the longitudinal pipes and the cross pipe. By making die cast products portions of constituent parts, the fabrication cost of the vehicle body frame can be reduced.

Abstract: To adopt die cast products as parts of a vehicle body frame. A vehicle body frame is provided with an alumite treating, showing that brightness and appearance of pivot plates which are die cast products differ from those of non-die cast products, head pipes, longitudinal pipes and cross pipe. By carrying out a local coating treatment on the pivot plates, the pivot plates are provided with a color the same as that of the head pipe, the longitudinal pipes and the cross pipe. By making die cast products portions of constituent parts, the fabrication cost of the vehicle body frame can be reduced.

Abstract: An aluminum alloy die casting method comprising the steps of providing a die casting machine having a gate for allowing passage of molten aluminum alloy, setting a flow rate of the molten aluminum alloy at the gate to be in a range of 5 m/sec to 15 m/sec, and press-injecting the molten aluminum alloy into a cavity of a die. With this arrangement, it becomes possible to obtain a weldable casting with no entrapment of air. An aluminum alloy for a vehicular part, which is formed of a die cast product manufactured by the die casting method of the present invention, is weldable and also dense in structure. As a result, these vehicular parts formed of the die-cast products are manufactured on a large scale at a low cost.

Abstract: An aluminum alloy comprises magnesium in a range of 3.0% by weight≦Mg≦5.5% by weight, manganese in a range of 1.5% by weight≦Mn≦2.0% by weight, nickel in a range of 0.5% by weight≦Ni≦0.9% by weight, and the balance of aluminum including inevitable impurities. Particularly, the Ni content is set in the above range in order to achieve an increase in toughness of a die-cast product. Thus, it is possible to suppress the amount of an intermetallic compound AlMnNi produced and to finely divide the intermetallic compound AlMnNi.