A cycle is repeated a plurality of times, which includes a forging process for placing a material to be forged in a lower die and pressing the material to be forged in this state and then separating an upper die from the material to be forged; an elevation process for lifting the material to be forged by using an elevation device to separate the material to be forged from the lower die; a rotation process for rotating the material to be forged around its center by using a rotation device; and a lowering process for placing the material to be forged rotated by the elevation device in the lower die.

A cycle is repeated a plurality of times, which includes a forging process for placing a material to be forged in a lower die and pressing the material to be forged in this state and then separating an upper die from the material to be forged; an elevation process for lifting the material to be forged by using an elevation device to separate the material to be forged from the lower die; a rotation process for rotating the material to be forged around its center by using a rotation device; and a lowering process for placing the material to be forged rotated by the elevation device in the lower die.

Various implementations include a method of manufacturing a ring molded article. The ring molded article has two convex portions which respectively protrude on both sides of the ring molded article in a direction of a center axis thereof and extend in a direction of a circumference of the ring molded article. The ring material is placed inside two molds on which concave portions respectively corresponding to the convex portions are formed. The ring material is supported by a region on an outer peripheral side from an outer peripheral side corner in the concave portion of one of the two molds and a region on an inner peripheral side from an inner peripheral side corner in the concave portion of another of the two molds. The ring material is then forged so as to be pressed by the two molds in a direction of a center axis of the ring material.

A high-strength stainless steel rotor and a method for preparing the same, are provided. The high-strength stainless steel rotor, including the following element components by mass percentage: C: 0.03-0.050%, Cr: 14.90-15.80%, Ni: 5.00-5.70%, Cu: 2.20-2.80%, (Nb+Ta): 0.35-0.44%, Mo: 0.45-0.54%, V: 0.06-0.10%, Si: 0.20-0.60%, Mn: 0.40-0.80%, P?0.010%, S?0.010%, O?0.003%, and the balance of iron and inevitable impurities.

Aluminum wheels include a rim and a disc having a mounting portion. The mounting portion includes an inner mounting face and an outer mounting face. The mounting portion also includes a coarse grain region and a fine grain region. The coarse grain region can be adjacent, and at least partially form, one of the inner mounting face or the outer mounting face. The coarse grain region includes aluminum alloy grains of a first average grain length that is greater than 1 mm. The fine grain region extends between the coarse grain region and the other of the inner mounting face or the outer mounting face. The fine grain region includes aluminum alloy grains of a second average grain length that is less than 0.5 mm.

Aluminum alloys described herein include silicon, iron, copper, manganese, magnesium, and chromium. In various implementations, the aluminum alloys also include one or more of zinc and titanium. Typically, a total amount of iron and manganese in the aluminum alloys is no less than 0.28% by weight and no greater than 0.45% by weight, and the grains in the aluminum alloys have an average grain length of no greater than 6 mm. Aluminum alloy billets can be forged for wheel production at selected temperatures.

Aluminum alloys described herein include silicon, iron, copper, manganese, magnesium, and chromium. In various implementations, the aluminum alloys also include one or more of zinc and titanium. Typically, a total amount of iron and manganese in the aluminum alloys is no less than 0.28% by weight and no greater than 0.45% by weight, and the grains in the aluminum alloys have an average grain length of no greater than 6 mm. Aluminum alloy billets can be forged for wheel production at selected temperatures.

A brake disc to be mounted on an axle hub, including sliding surfaces with which friction members respectively come into a sliding contact and which face in mutually opposite directions, wherein the brake disc includes: a first member having a disc-like shape and including a mount portion through which the brake disc is mounted on an axle hub and a radially outer portion located radially outward of the mount portion, one of the sliding surfaces being formed on the radially outer portion; and a second member having a doughnut plate shape, the other of the sliding surfaces being formed on the second member, and wherein the first member and the second member are bonded through a protruding portion formed on one of the radially outer portion of the first member and the second member and protruding toward the other of the radially outer portion and the second member.

A brake disc to be mounted on an axle hub, including sliding surfaces with which friction members respectively come into a sliding contact and which face in mutually opposite directions, wherein the brake disc includes: a first member having a disc-like shape and including a mount portion through which the brake disc is mounted on an axle hub and a radially outer portion located radially outward of the mount portion, one of the sliding surfaces being formed on the radially outer portion; and a second member having a doughnut plate shape, the other of the sliding surfaces being formed on the second member, and wherein the first member and the second member are bonded through a protruding portion formed on one of the radially outer portion of the first member and the second member and protruding toward the other of the radially outer portion and the second member.

A metal component is produced using a casting-and-forming tool by casting a melt of a metal alloy into the casting-and-forming tool, wherein the melt is poured from above into a base part or reservoir of the casting-and-forming tool at a first pressure, applying pressure to the melt between the base part and an upper part while the melt is solidifying to a component, wherein the solidifying melt is pressurized at a second pressure, which is larger than the first pressure, when the melt is at least partly, i.e., mostly solidified to form a component compressing the component by relative movement of the base part to the upper part so as to compress the component with a third pressure, which is higher than the second pressure.