Methods for strengthening slowly-quenched/cooled cast aluminum components

A method of increasing the durability of at least one of a cylinder head and an engine block by improving a mechanical property of a permanent mold heat treatable aluminum alloy cast in permanent mold comprising:

• providing the heat treatable aluminum alloy in molten form to a cast in permanent mold defined in a shape of the at least one of the cylinder head and the engine block wherein the alloy is not subjected to high pressure die casting;
• heat treating the aluminum alloy at a solution treatment temperature for the aluminum alloy for a first period of time;
• heating the heat treated aluminum alloy to a temperature about 5° C. to about 30° C. above the solution treatment temperature;
• cooling the heated aluminum alloy in air to room temperature;
• pre-aging the cooled aluminum alloy at a temperature in a range of about room temperature to about 100° C.;
• and
• performing subsequent steps of aging after preaging to improve tensile strength of the at least one of the cylinder head and the engine block by aging the pre-aged aluminum alloy by two-step aging at an aging temperature in a range of about 140° C. to about 240° C. and then at a second aging temperature higher than the aging temperature, wherein the pre-aging and the aging steps are each at least an hour;
• and wherein the temperature changes following pre-aging are either in steps, in a continuous manner, or a combination thereof.

A method of increasing the durability of at least one of a cylinder head and an engine block by improving a mechanical property of a permanent mold heat treatable aluminum alloy cast in permanent mold comprising:

• providing the heat treatable aluminum alloy in molten form to a cast in permanent mold defined in a shape of the at least one of the cylinder head and the engine block wherein the alloy is not subjected to high pressure die casting;
• heat treating the aluminum alloy;
• cooling the heated aluminum alloy in air;
• pre-aging the aluminum alloy at a temperature in a range of about room temperature to about 100° C.;
• and
• performing subsequent steps of aging after preaging to improve tensile strength of the at least one of the cylinder head and the engine block by non-isothermally aging the pre-aged aluminum alloy by two-step aging at an aging temperature above the pre-aging temperature and then at a second aging temperature higher than the aging temperature, wherein the pre-aging and the aging steps are each at least an hour;
• and wherein the temperature changes following pre-aging are either in steps, in a continuous manner, or a combination thereof.