The invention discloses a 300MPa-grade high-strength and high-
plasticity non-heat treatable self-strengthening die-
casting aluminum
alloy and a manufacturing method. The 300MPa-grade high-strength andhigh-
plasticity non-heat treatable self-strengthening die-
casting aluminum
alloy is prepared from components in percentage by
mass as follows: 7.5%-8.5% of Si, 1.0%-1.3% of Cu, 0.1%-0.3% of Fe, 0.7%-1.0% of Mn, 0.35%-0.5% of Mg, 0.1%-0.2% of Ti, 0.05%-0.1% of Cr, 0.02%-0.03% of Sr and the balance Al. The manufacturing method comprises the following steps: after remelting a pure aluminum
ingot, melting in other components, and after complete melting, uniformly stirring the components until no sediments exist at the bottom of a furnace; keeping
molten metal at 720 DEG C at constant temperaturefor 30 min, performing deslagging and degassing, decreasing the temperature of the
molten metal to 680-690 DEG C, and pressing pure Mg wrapped by
aluminum foil into molten aluminum by a
bell jar; carrying out uniform stirring for 5-10 min after complete
smelting, and carrying out deslagging; and after
smelting,
casting the
molten metal into a
metal die by a horizontal cold chamber die-casting
machine to obtain an
alloy casting. The manufactured non-heat treatable self-strengthening die-casting aluminum alloy has tensile strength up to 300 MPa or above and elongation larger than or equal to 8%before heat treatment, so that the aluminum alloy is a novel high-strength and high-
plasticity aluminum alloy and can be popularized and used in the industry.