| 摘要 |
PROBLEM TO BE SOLVED: To provide a manufacturing method of a cast product with a sand mold casting, with which the toughness can be improved without damaging the fatigue strength in the cast product. SOLUTION: This manufacturing method is composed of the following processes, i.e., a molten metal pouring process for pouring the molten metal 10 into a cavity in the sand mold 11, a solidified process for forming the casting 14 by solidifying the molten metal in the cavity 12 and a shot blast treatment process for removing the sand 16 stuck on the surface part of the casting 14 by applying the impact onto the surface 14a of the casting 14 taken out from the sand mold 11 with granular medium 17. Further, an annealing treatment process for annealing the casting 14 after the shot blast treatment to recover the toughness of the casting 14 lowered with the shot blast treatment into the originally possessed toughness in the casting 14 and a shot peening treatment process for applying the impact energy with the granular medium 8 at lower than the impact energy applied with the shot blast treatment onto the surface 14a of the casting 14 after the annealing treatment to make the fatigue strength of the casting 14 lowered with the annealing treatment into the same or more of the fatigue strength possessed in the casting 14 after shot blast treatment are successively executed.
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