| abstract |
PURPOSE:To improve resistance against thermal shock and resistance against fatigue by rapidly remelting and quenching the heat spot part and edge part of a piston head part in an aluminium alloy piston formed through metal mold casting. CONSTITUTION:A piston body 1 for direct injection Diesel internal-combustion engine is made of a metal mold-cast alluminium alloy, and the hot spot part 2 of a piston head is obtained by locally concentrating high density energy such as electron beams, a laser, plasma, and TIG arc and allowing said spot part to be remelted at a high speed. And, a remelted part is quenched and its texture is made fine bystopping the heating before the ambient temperature is raised. |