Method for making high strength aluminum alloy sheet and products made by same

Abstract

Disclosed is a method for producing a non-heat-treatable high strength aluminum sheet from aluminum scraps using a continuous caster. The method includes providing a molten aluminum non-heat-treatable alloy including Si about 0.7% max., Fe about 0.8% max., Cu about 0.3% max., Mn about 0.5-1.2%, Mg about 1.3-2.8%, Zn about 0.20% max., Cr about 0.2% max., Zr about 0.30% max., Sr about 0.30 max., the remainder aluminum, incidental elements and impurities; and continuously casting the molten aluminum alloy into a slab and rolling the slab into a sheet product with high strength and reasonable formability. Typically, the sheet product is used for the products, such as truck trailer siding panel or electrical conduits for the building industry.

1 . A method for making an aluminum sheet product of non-heat-treatable alloy comprising the steps of:
 providing a molten non-heat-treatable aluminum alloy comprising:
 Si about 0.7% max., 
 Fe about 0.8% max., 
 Cu about 0.3% max., 
 Mn about 0.5-1.2%, 
 Mg about 1.3-2.8%, 
 Zn about 0.20% max., 
 Cr about 0.20% max., 
 Zr about 0.30% max., 
 Sr about 0.30% max., 
   the remainder aluminum, incidental elements and impurities present, if any, in amounts of about 0.05 wt. % max. each, about 0.15 wt. % max. total;   continuously casting the alloy in a continuous caster into a slab having a thickness of about 0.1 to 2 inches;   rolling the slab to form the aluminum sheet product of non-heat-treatable alloy, wherein the rolling comprises hot rolling;   wherein the aluminum sheet product has a yield strength of about 20 to 45 and an ultimate tensile strength of about 30 to 60 ksi, and elongation of about 4 to 16% and wherein the product is made in the absence of solution heat treatment.   
   
   
       2 . The method of  claim 1 , wherein the hot rolling starts in a temperature range of about 700° to 1050° F. and ends in a temperature of about 350° to 700° F. and reduces the thickness of the slab about 60 to 98% of the original thickness of the slab. 
   
   
       3 . The method of  claim 1 , wherein the total YTS increase from slab condition to the exit of the hot rolling is in the range of about 165% to 435%. 
   
   
       4 . The method of  claim 1 , wherein hot rolling occurs in a three stand hot rolling mill wherein the yield tensile strength (YTS) increase after the first rolling stand should be in the range of about 70 to 110%, the YTS increase after the second rolling stand should be about 30 to 70% greater than the strength from the first rolling stand and the YTS increase after third hot rolling stand should be about 20 to 50% greater than the strength from the second rolling stand. 
   
   
       5 . The method of  claim 1 , wherein the method forms the aluminum sheet product in the absence of annealing. 
   
   
       6 . The method of  claim 1 , wherein the cold rolling provides about a 20 to 90% gauge reduction. 
   
   
       7 . The method of  claim 1 , wherein the hot rolled sheet is annealed in a temperature range of about 600° to 1100° F. prior to cold rolling. 
   
   
       8 . The method of  claim 1 , wherein the cold rolled sheet is annealed in a temperature range of about 300° F. to 750° F. 
   
   
       9 . The method of  claim 1 , wherein the hot rolled sheet is annealed in a first annealing step to form an annealed sheet, the annealed sheet of the first annealing step is cold rolled, and the cold rolled sheet is annealed in a second annealing step to form the aluminum sheet product. 
   
   
       10 . The method of  claim 1 , wherein the high strength sheet product is strain hardened to an H1x temper. 
   
   
       11 . The method of  claim 1 , wherein the high strength sheet product is strain hardened and partial annealed to H2x or stabilized to H3x tempers. 
   
   
       12 . The method of  claim 1 , wherein the sheet product has a yield strength >about 36 ksi and ultimate strength >about 40 ksi. 
   
   
       13 . The method of  claim 1 , wherein the sheet product has a yield strength of >about 38 ksi, ultimate strength >about 42 ksi. 
   
   
       14 . The method of  claim 1 , wherein the aluminum sheet product has a thickness of about 0.01 to 0.08 inches, UTS about 30-45 ksi, and YTS about 25-40 ksi %. 
   
   
       15 . The method of  claim 1 , wherein the continuous caster is a belt caster or a block caster. 
   
   
       16 . The method of  claim 1 , wherein the hot rolled sheet product is cold rolled to a thickness in the range of about 0.01 inch to 0.1 inch. 
   
   
       17 . The method of  claim 1 , further comprising forming the aluminum sheet product into a truck trailer panel having a thickness of about 0.01 to 0.19 inches, yield strength >about 36 ksi, and ultimate strength >about 40 ksi and elongation of 4 to 10%. 
   
   
       18 . The method of  claim 1 , further comprising forming the aluminum sheet product into a truck trailer panel having a thickness of about 0.01 to 0.19 inches, yield strength >about 38 ksi, and ultimate strength >about 42 ksi and elongation of 4 to 10%. 
   
   
       19 . The method of  claim 1 , further comprising forming the aluminum sheet product into an electrical conduit having a thickness of about 0.01 to 0.08 inches, having UTS about 30-45 ksi, and YTS about 25-40 ksi and elongation of 6 to 16%. 
   
   
       20 . The method of  claim 1 , wherein, the alloy has the following composition:
 Si about 0.25-0.7%,   Fe about 0.35-0.8%,   Cu about 0.05-0.28%,   Mn about 0.5-1.0%,   Mg about 1.3-2.5%,   Zn about 0.20% max.,   Cr about 0.20% max.,   Zr about 0.25% max.,   Sr about 0.25% max.,   the remainder aluminum, incidental elements and impurities present, if any, in amounts of about 0.05 wt. % max. each, about 0.15 wt. % max. total.   
   
   
       21 . A method for making an aluminum sheet product of non-heat-treatable alloy comprising the steps of:
 providing a molten aluminum alloy comprising:
 Si about 0.7% max., 
 Fe about 0.8% max., 
 Cu about 0.3% max., 
 Mn about 0.5-1.2%, 
 Mg about 1.3-2.8%, 
 Zn about 0.20% max., 
 Cr about 0.20% max., 
 Zr about 0.30% max., 
 Sr about 0.30% max., 
   the remainder aluminum, incidental elements and impurities present, if any, in amounts of about 0.05 wt. % max. each, about 0.15 wt. % max. total;   continuously casting the alloy in a continuous caster into a slab having a thickness of about 0.1 to 1 inch,   cold rolling the continuously cast slab to form the aluminum sheet product, wherein the method has an absence of hot rolling;   wherein the aluminum sheet product has a yield strength of about 20 to 45 ksi, an ultimate tensile strength of about 30 to 60 ksi, and elongation of 4 to 16%.   
   
   
       22 . The method of  claim 21 , wherein the continuous caster is a roll caster or belt caster. 
   
   
       23 . The method of  claim 21 , wherein the cold rolling provides about a 60 to 98% gauge reduction. 
   
   
       24 . The method of  claim 21 , wherein, the alloy has the following composition:
 Si about 0.25-0.7%,   Fe about 0.35-0.8%,   Cu about 0.05-0.28%,   Mn about 0.5-1.0%,   Mg about 1.3-2.5%,   Zn about 0.15% max.,   Cr about 0.15% max.,   Zr about 0.25% max.,   Sr about 0.25% max.   the remainder aluminum, incidental elements and impurities present, if any, in amounts of about 0.05 wt. % max. each, about 0.15 wt. % max. total.   
   
   
       25 . A truck trailer siding made from a non-heat-treatable aluminum alloy sheet in an H temper comprising:
 Si about 0.7% max.,   Fe about 0.8% max.,   Cu about 0.3% max.,   Mn about 0.5-1.2%,   Mg about 1.3-2.8%,   Zn about 0.20% max.,   Cr about 0.20% max.,   Zr about 0.30% max.,   Sr about 0.30% max.,   the remainder aluminum, incidental elements and impurities present, if any, in amounts of about 0.05 wt. % max. each, about 0.15 wt. % max. total;   having a thickness of about 0.01 to 0.19 inches, a yield strength >about 36 ksi, ultimate strength >40 ksi and elongation about 4 to 10% as measured.   
   
   
       26 . An electrical conduit made from a non-heat-treatable aluminum alloy sheet in an H temper comprising:
 Si about 0.7% max.,   Fe about 0.8% max.,   Cu about 0.3% max.,   Mn about 0.5-1.2%,   Mg about 1.3-2.8%,   Zn about 0.20% max.,   Cr about 0.20% max.,   Zr about 0.30% max.,   Sr about 0.30% max.,   the remainder aluminum, incidental elements and impurities present, if any, in amounts of about 0.05 wt. % max. each, about 0.15 wt. % max. total;   having a thickness of about 0.01 to 0.07 inches, ultimate strength at least about 30 ksi and elongation about 6 to 16%.