Casting, thermal transforming and semi-solid forming aluminum alloys

A process for casting, thermally transforming and semi-solid forming an aluminum base alloy into an article, the process comprising the steps of:

• (a) providing a molten body of said aluminum base alloy comprising 4 to 9 wt. % silicon, 0.2 to 2.0 wt. % magnesium, and 0.02 to 0.15 wt. % titanium, balance aluminum and incidental elements and impurities;
• (b) casting said molten body of aluminum base alloy to provide a solidified body, said molten aluminum base alloy being solidified at a rate between liquidus and solidus temperatures of the aluminum base alloy in a range of 5.degree. to 100.degree. C./sec. to provide an entire solidified body having a dendritic microstructure having a grain size in the range of 20 to 250 .mu.m and a dendritic arm spacing of 2 to 50 .mu.m;
• (c) thereafter, applying heat by inductively heating said solidified body to bring said solidified body to a superheated temperature of 3.degree. to 50.degree. C. above said solidus temperature of said aluminum base alloy, said heating to said superheated temperature being at a rate in the range of 200.degree. to 1000.degree. C./min;
• (d) effecting thermal transformation of said entire body having said dendritic structure to a globular structure contained in a lower melting eutectic when said entire body is uniformly heated to said superheated temperature;
• and
• (e) forming said body having said globular structure in a semi-solid condition into said article.

A process for casting, thermally transforming and semi-solid forming an aluminum base alloy into an article, the process comprising the steps of:

• (a) providing a molten body of said aluminum base alloy comprising 2 to 10.6 wt. % magnesium, less than 2.5 wt. % silicon, and 0.02 to 0.15 wt. % titanium, the remainder comprising aluminum, incidental elements and impurities;
• (b) casting said molten body of aluminum base alloy to provide a solidified body, said molten aluminum base alloy being solidified at a rate between liquidus and solidus temperatures of the aluminum base alloy in a range of 5.degree. to 100.degree. C./sec to provide an entire solidified body having a dendritic microstructure having a grain size in the range of 20 to 250 .mu.m;
• (c) thereafter, heating said solidified body to bring said body to a superheated temperature of 3.degree. to 50.degree. C. above said solidus temperature of said aluminum base alloy while maintaining said body in a solid shape, said heating to said superheated temperature being at a rate greater than 30.degree. C. per minute;
• (d) effecting thermal transformation of said entire body having said dendritic structure when said entire body is uniformly heated to said superheated temperature;
• and
• (e) forming said body having said globular structure in a semi-solid condition into said article.

A process for casting, thermally transforming and semi-solid forming an aluminum base alloy into an article, the process comprising the steps of:

• (a) providing a molten body of said aluminum base alloy comprising 0.2 to 2.4 wt. % magnesium, 2 to 8 wt. % zinc, the remainder aluminum, incidental elements and impurities;
• (b) casting said molten body of aluminum base alloy to provide a solidified body, said molten aluminum base alloy being solidified at a rate between liquidus and solidus temperatures of the aluminum base alloy in a range of 5.degree. to 100.degree. C./sec. to provide an entire solidified body having a dendritic microstructure;
• (c) thereafter, heating said solidified body to bring said body to a superheated temperature of 3.degree. to 50.degree. C. above said solidus temperature of said aluminum base alloy while maintaining said body in a solid shape, said heating to said superheated temperature being at a rate greater than 30.degree. C. per minute;
• (d) effecting thermal transformation of said entire body having said dendritic structure when said entire body is uniformly heated to said superheated temperature;
• and
• (e) forming said body having said non-dendritic structure in a semi-solid condition into said article.

A process for casting, thermally transforming and semi-solid forming an aluminum base alloy into an article, the process comprising the steps of:

• (a) providing a molten body of said aluminum base alloy comprising 6.5 to 7.5 wt. % silicon, 0.25 to 0.45 wt. % magnesium, less than 0.15 wt. % titanium, the remainder aluminum, incidental elements and impurities;
• (b) casting said molten body of aluminum base alloy to provide a solidified body, said molten aluminum base alloy being solidified at a rate between liquidus and solidus temperatures of the aluminum base alloy in a range of 5.degree. to 100.degree. C./sec to provide an entire solidified body having a dendritic microstructure having a grain size in the range of 20 to 250 .mu.m;
• (c) thereafter, heating said solidified body to bring said body to a superheated temperature of 3.degree. to 50.degree. C. above said solidus temperature of said aluminum base alloy while maintaining said body in a solid shape, said heating to said superheated temperature being at a rate greater than 30.degree. C. per minute;
• (d) effecting thermal transformation of said entire body having said dendritic structure when said entire body is uniformly heated to said superheated temperature;
• and
• (e) forming said body having said non-dendritic structure in a semi-solid condition into said article.

A process for casting, thermally transforming and semi-solid forming an aluminum base alloy to provide an article substantially free of porosity, the process comprising the steps of:

• (a) providing a molten body of said aluminum base alloy;
• (b) casting said molten body of aluminum base alloy to provide a solidified body, said molten aluminum base alloy being solidified at a rate between liquidus and solidus temperatures of the aluminum base alloy in a range of 5.degree. to 100.degree. C./sec. to provide a solidified body having a dendritic microstructure;
• (c) homogenizing said solidified body;
• (d) thereafter, applying heat to said solidified body to bring said body to a superheated temperature of 3.degree. to 50.degree. C. above said solidus temperature of said aluminum base alloy while maintaining said body in a solid shape;
• (e) effecting thermal transformation of said body having said dendritic structure when said body is uniformly heated to said superheated temperature;
• and
• (f) forming said body having said non-dendritic structure in a semi-solid condition into said article substantially free of porosity.

A process for casting, thermally transforming and semi-solid forming an aluminum base alloy into an article, the process comprising the steps of:

• (a) providing a molten body of said aluminum base alloy comprising 4 to 9 wt. % silicon, 0.2 to 2.0 wt. % magnesium, and 0.02 to 0.15 wt. % titanium, balance aluminum and incidental elements and impurities;
• (b) casting said molten body of aluminum base alloy to provide a solidified body, said molten aluminum base alloy being solidified at a rate between liquidus and solidus temperatures of the aluminum base alloy in a range of 5.degree. to 100.degree. C./sec. to provide an entire solidified body having a dendritic microstructure having a grain size in the range of 20 to 250 .mu.m and a dendritic arm spacing of 2 to 50 .mu.m;
• (c) thereafter, applying heat by inductively heating said solidified body to bring said solidified body to a superheated temperature of 3.degree. to 50.degree. C. above said solidus temperature of said aluminum base alloy, said rate of heating to said superheated temperature being at a rate in the range of 200.degree. to 1000.degree. C./min;
• (d) effecting thermal transformation of said entire body having said dendritic structure to a globular structure contained in a lower melting eutectic when said entire body is uniformly heated to said superheated temperature;
• (e) maintaining said aluminum base alloy body between said solidus temperature and said superheated temperature for a time sufficient to effect thermal transformation of the dendritic microstructure to provide a body having a globular structure contained in a lower melting liquid phase;
• and
• (f) forming said body having said globular structure in a semi-solid condition into said article.

In a method of semi-solid forming shaped aluminum alloy articles wherein the aluminum alloy is provided as a billet, the improvement wherein said billet is provided in an aluminum base alloy comprising 2 to 11 wt. % silicon, 0.2 to 0.7 wt. % magnesium, 0.01 to 0.15 wt. % titanium, the balance aluminum, incidental elements and impurities, said shaped article further being provided in the condition resulting from:

• (a) casing said molten body of aluminum base alloy to provide a solidified body, said molten aluminum base alloy being solidified at a rate between liquidus and solidus temperatures of the aluminum base alloy to provide a solidified body having a dendritic grain microstructure having a grain size in the range of 20 to 250 .mu.m;
• (b) thereafter, heating said solidified body to bring said body to a superheated temperature of 3.degree. to 50.degree. C. above said solidus temperature of said aluminum base alloy, said heating to said superheated temperature being at a rate greater than 30.degree. per minute;
• (c) effecting thermal transformation of said dendritic structure to a non-dendritic structure when said body is uniformly heated to said superheated temperature;
• and
• (d) forming said body having said non-dendritic structure in a semi-solid condition into said article.

In a method of semi-solid forming shaped aluminum alloy articles wherein the aluminum alloy is provided as a billet, the improvement wherein said billet is provided in an aluminum base alloy comprising 2 to 11 wt. % silicon, 0.2 to 0.7 wt. % magnesium, 0.01 to 0.15 wt. % titanium, the balance aluminum, incidental elements and impurities, said shaped article further being provided in the condition resulting from:

• (a) casting said molten body of aluminum base alloy to provide a solidified body, said molten aluminum base alloy being solidified at a rate between liquidus and solidus temperatures of the aluminum base alloy in a range of 5.degree. to 100.degree. C./sec to provide a solidified body having a dendritic microstructure having a grain size in the range of 20 to 200 .mu.m;
• (b) thereafter, inductively heating said solidified body to a superheated temperature of 3.degree. to 50.degree. C. above said solidus temperature of said aluminum base alloy, said rate of heating to said superheated temperature being at a rate in the range of 200.degree. to 1000.degree. C./min;
• (c) maintaining said body at said superheated temperature for a period in the range of 1 to 60 seconds and effecting thermal transformation of said dendritic microstructure to said globular form in said body;
• and
• (d) forming said body having said globular structure in a semi-solid condition into said article.

In a method of semi-solid forming shaped aluminum alloy articles wherein the aluminum alloy is provided as a billet, the improvement wherein said billet is provided in an aluminum base alloy comprising 2 to 10.6 wt. % magnesium, less than 2.5 wt. % silicon, and 0.02 to 0.15 wt. % titanium, the remainder comprising aluminum, incidental elements and impurities, said shaped article further being provided in the condition resulting from:

• (a) casting said molten body of aluminum base alloy to provide a solidified body, said molten aluminum base alloy being solidified at a rate between liquidus and solidus temperatures of the aluminum base alloy in a range of 5.degree. to 100.degree. C./sec to provide a solidified body having a dendritic microstructure having a grain size in the range of 20 to 250 .mu.m;
• (b) thereafter, heating said solidified body to bring said body to a superheated temperature of 3.degree. to 50.degree. C. above said solidus temperature of said aluminum base alloy, said heating to said superheated temperature being at a rate greater than 30.degree. C. per minute;
• (c) effecting thermal transformation of said dendritic structure to a non-dendritic structure when said body is uniformly heated to said superheated temperature;
• and
• (d) forming said body having said globular structure in a semi-solid condition into said article.