PROCESS FOR PRODUCTION OF ROUGHLY SHAPED MATERIAL FOR ENGINE PISTON

A production method of a roughly shaped material for an engine piston includes a continuous casting step for obtaining a cast rod (31) having a diameter of 85 mm or less by continuously casting a molten aluminum alloy (30) at a molten alloy temperature of 720 °C or higher, and a forging step for obtaining a roughly shaped material (11) for an engine piston by forging a forging material (32) obtained by homogenizing the cast bar (31) at 370 to 500 °C. A composition of the molten alloy (30) includes Si: 11.0 to 13.0 mass%, Fe: 0.6 to 1.0 mass%, Cu: 3.5 to 4.5 mass%, Mn: 0.25 mass% or less; Mg: 0.4 to 0.6 mass%, Cr: 0.15 mass% or less, Zr: 0.07 to 0.15 mass%, P: 0.005 to 0.010 mass%, Ca: 0.002 mass% or less, and the balance being Aluminum and inevitable impurities.