Forged piston, internal combustion engine, transportation apparatus and method of making the forged piston

摘要

A method of making a forged piston includes the steps of providing a workpiece made of an aluminum alloy, a magnesium alloy or a titanium alloy; and forging the workpiece with stress applied thereto in a predetermined direction (forging direction). The method further includes, before the step of forging, the step of working the workpiece such that fiber flows of the workpiece are nonparallel to the predetermined direction.