High-strength casting aluminium-silicon alloy for piston and preparation method thereof

The invention relates to a casting aluminium-silicon alloy for motor piston and a preparation method thereof, belonging to the field of metal materials. The aluminium-silicon alloy comprises 12.0-14.0 wt% of Si, less than 0.3 wt% of Ni, 1.8-3.0 wt% of Cu, 0.3-0.8 wt% of Fe, 0.3-0.6 wt% of Mn, less than 0.4 wt% of Mg, 0.1-0.2 wt% of Ti, less than 0.3 wt% of Zr and balance of Al. The heat treatment parameters are as follows: 510+/-5 DEG C*5-8h+water quenching under room temperature for solution treatment; and 160+/-5 DEG C*6-10h+air cooling for ageing treatment. The tensile strength and yield strength of the alloy under the room temperature reach 283-305MPa and 178-190MPa respectively and the elongtation percentage after breaking reaches 1.8-3.2%. Compared with similar alloys, the aluminium-silicon alloy of the invention has higher mechanical property, reduces Ni element content and noble metal element content of the alloy and allows Fe element to fluctuate in wider scope; the invention has good quality of ingot casting, simple process and strong operability.