Aluminum automotive structural members

Abstract

Disclosed is a method for producing aluminum vehicular structural parts or members such as from molten aluminum alloy using a continuous caster to cast the alloy into a slab. The method comprises providing a molten aluminum alloy consisting essentially of 2.7 to 3.6 wt. % Mg, 0.1 to 0.4 wt. % Mn, 0.02 to 0.2 wt. % Si, 0.05 to 0.30 wt. % Fe, 0.1 wt. % max. Cu, 0.25 wt. % max. Cr, 0.2 wt. % max. Zn, 0.15 wt. % max. Ti, the remainder aluminum, incidental elements and impurities and providing a continuous caster such as a belt caster, block caster or roll caster for continuously casting the molten aluminum alloy. The molten aluminum alloy is cast into a slab which is rolled into a sheet product and then annealed. The sheet has an improved distribution of intermetallic particles (Al—Fe, Al—Fe—Mn or Mg 2 Si) and improved formability. Thereafter, the sheet product is formed into the vehicular structural part or member with sufficient strength and formability required by automotive industry.

1 . In the production of an aluminum automotive structural part or member from a molten aluminum alloy using a continuous caster to cast the alloy into a slab, the method comprising:
 (a) providing a molten aluminum alloy consisting essentially of 2.7 to 3.6 wt. % Mg, 0.1 to 0.4 wt. % Mn, 0.02 to 0.2 wt. % Si, 0.05 to 0.30 wt. % Fe, 0.1 wt. % max. Cu, 0.25 wt. % max. Cr, 0.2 wt. % max. Zn, 0.15 wt. % max. Ti, the remainder aluminum, incidental elements and impurities;   (b) providing a continuous caster for continuously casting said molten aluminum alloy;   (c) casting said molten aluminum alloy into a slab having Al—Fe, Al—Fe—Mn or Mg 2 Si intermetallic particles;   (d) rolling said slab into a sheet product;   (e) annealing said sheet product to an O-temper condition, said sheet having substantially uniform distribution or minimized striations of said intermetallic particles and have an average grain size in the range of about 15 to 20 μm; and   (f) forming said sheet in said O-temper into said structural part or member by stamping at room temperature.   
     
     
         2 . In the production of the aluminum structural member in accordance with  claim 1  wherein manganese is maintained in the range of 0.1 to 0.35 wt. %. 
     
     
         3 . In the production of the aluminum structural part or member in accordance with  claim 1  wherein magnesium is maintained in the range of 2.8 to 3.5 wt. %. 
     
     
         4 . In the production of the aluminum structural part or member in accordance with  claim 1  wherein iron is maintained in the range of 0.5 to 0.25 wt. %. 
     
     
         5 . In the production of the aluminum structural part or member in accordance with  claim 1  wherein said continuous caster is a belt caster, a block caster or a roll caster. 
     
     
         6 . In the production of the aluminum structural part or member in accordance with  claim 1  including annealing said sheet product in a temperature range of 650° to 950° F. 
     
     
         7 . In the production of the aluminum structural part or member in accordance with  claim 1  including annealing said sheet product in a temperature range of 700° to 900° F. 
     
     
         8 . In the production of the aluminum structural part or member in accordance with  claim 7  including annealing for about 2 to 10 hours. 
     
     
         9 . In the production of the aluminum structural part or member in accordance with  claim 1  including continuously annealing said sheet product. 
     
     
         10 . In a method for the production of an aluminum automotive structural part or member from molten aluminum alloy using a continuous caster to cast the alloy into a slab, the method comprising:
 (a) providing a molten aluminum alloy consisting essentially of 2.7 to 3.6 wt. % Mg, 0.1 to 0.4 wt. % Mn, 0.02 to 0.2 wt. % Si, 0.05 to 0.30 wt. % Fe, 0.1 wt. % max. Cu, 0.25 wt. % max. Cr, 0.2 wt. % max. Zn, 0.15 wt. % max. Ti, the remainder aluminum, incidental elements and impurities;   (b) providing a continuous caster for continuously casting said molten aluminum alloy;   (c) casting said molten aluminum alloy into a slab having a thickness in the range of 0.2 inch to 2 inch and having Al—Fe, Al—Fe—Mn or Mg 2 Si intermetallic particles;   (d) hot rolling said slab into a hot rolled sheet product, said hot rolling starting in a temperature range of 750° to 1000° F. and ending in a temperature of 400° to 825° F.;   (e) annealing said hot rolled sheet product to an O-temper condition, said hot rolled sheet product in said condition having a tensile strength in the range of 28 to 35 ksi, a yield strength in the range of 12 to 17.5 ksi, and an elongation greater than 19% and having substantially uniform distribution or minimized striations of said intermetallic particles and have an average grain size in the range of about 15 to 20 μm; and   (f) forming said sheet product in said 0-temper condition into said structural part or member by stamping at room temperature.   
     
     
         11 . The method in accordance with  claim 10  wherein magnesium is maintained in the range of 2.8 to 3.5 wt. %. 
     
     
         12 . The method in accordance with  claim 10  wherein iron is maintained in the range of 0.05 to 0.25 wt. %. 
     
     
         13 . The method in accordance with  claim 10  including annealing said hot rolled sheet in a temperature range of 650° to 950° F. 
     
     
         14 . The method in accordance with  claim 10  including annealing said hot rolled sheet in a temperature range of 700° to 900° F. 
     
     
         15 . The method in accordance with  claim 13  including annealing for about 2 to 10 hours. 
     
     
         16 . The method in accordance with  claim 10  including continuously annealing said sheet product. 
     
     
         17 . A method for producing aluminum vehicular part or member from molten aluminum alloy using a continuous caster to cast the alloy into a slab, the method comprising:
 (a) providing a molten aluminum alloy consisting essentially of 2.7 to 3.6 wt. % Mg, 0.1 to 0.4 wt. % Mn, 0.02 to 0.2 Wt. % Si, 0.05 to 0.30 wt. % Fe, 0.1 wt. % max. Cu, 0.25 wt. % max. Cr, 0.2 wt. % max. Zn, 0.15 wt. % max. Ti, the remainder aluminum, incidental elements and impurities;   (b) providing a continuous caster for continuously casting said molten aluminum alloy into a slab having a thickness in the range of 0.2 inch to 2 inch;   (c) rolling said slab into a sheet product having a thickness in the range of 0.01 inch to 0.2 inch;   (d) annealing said rolled sheet product to provide a rolled and annealed sheet product having a tensile strength in the range of 28 to 35 ksi, a yield strength in the range of 12 to 17.5 ksi and an elongation greater than 19%, said rolled and annealed sheet product having a substantially uniform distribution or minimized striations of said intermetallic particles and have an average grain size in the range of about 15 to 20 μm; and   (e) forming said rolled and annealed sheet into a vehicular structural part or member by stamping at room temperature.   
     
     
         18 . The method in accordance with  claim 17  wherein said rolled sheet product has Al—Fe, Al—Fe—Mn or Mg 2 Si intermetallic particles formed during solidification in a size range of 0.05 to 10 μm. 
     
     
         19 . A process for producing plural panel automotive members having inner and outer panels connected to form said members, said inner panels having threaded fasteners securely crimped into said inner panels to provide means for bolting accessories to said automotive member, said inner panel formed by the process comprising:
 (a) providing a molten aluminum alloy consisting essentially of 2.7 to 3.6 wt. % Mg, 0.1 to 0.4 wt. % Mn, 0.02 to 0.2 wt. % Si, 0.1 to 0.25 wt. % Fe, 0.1 wt. % max. Cu, 0.25 wt. % max. Cr, 0.2 wt. % max. Zn, 0.15 wt. % max. Ti, the remainder aluminum, incidental elements and impurities;   (b) providing a continuous caster for continuously casting said molten aluminum alloy;   (c) casting said molten aluminum alloy into a slab having Al—Fe, Al—Fe—Mn or Mg 2 Si intermetallic particles;   (d) rolling said slab into a sheet product;   (e) annealing said sheet product to an O-temper condition, said sheet having substantially uniform distribution or minimized striations of said intermetallic particles and have an average grain size in the range of about 15 to 20 m;   (f) forming a portion of said sheet product in said O-temper into said inner panels by stamping at room temperature to provide inner panels having raised portions and recessed portions to provide stiffeners to said inner panels;   (g) crimping at least one threaded fastener to said inner panel;   (h) providing an outer panel for joining to said inner panel; and   (i) connecting said outer panel to said inner panels to provide said plural panel automotive member having threaded fasteners joined thereto.   
     
     
         20 . A process for producing plural panel automotive members having inner and outer panels connected to form said members, said inner panels having threaded fasteners securely crimped into said inner panels to provide means for bolting accessories to said automotive member, said inner panel formed by the process comprising:
 (a) providing a molten aluminum alloy consisting essentially of 2.7 to 3.6 wt. % Mg, 0.1 to 0.4 wt. % Mn, 0.02 to 0.2 wt. % Si, 0.05 to 0.25 wt. % Fe, 0.1 wt. % max. Cu, 0.25 wt. % max. Cr, 0.2 wt. % max. Zn, 0.15 wt. % max. Ti, the remainder aluminum, incidental elements and impurities;   (b) providing a continuous caster for continuously casting said molten aluminum alloy;   (c) casting said molten aluminum alloy into a slab having a thickness in the range of 0.2 inch to 2 inch and having Al—Fe, Al—Fe—Mn or Mg 2 Si intermetallic particles;   (d) hot rolling said slab into a hot rolled sheet product, said hot rolling starting in a temperature range of 750° to 1000° F. and ending in a temperature of 4000 to 825° F.;   (e) annealing said hot rolled sheet product to an O-temper condition, said hot rolled sheet product in said condition having a tensile strength in the range of 28 to 35 ksi, a yield strength in the range of 12 to 17.5 ksi, and an elongation greater than 19% and having substantially uniform distribution or minimized striations of said intermetallic particles and have an average grain size in the range of about 15 to 20 μm;   (f) forming a portion of said sheet product in said O-temper into said inner panels by stamping at room temperature to provide inner panels having raised portions and recessed portions to provide stiffeners to said inner panels;   (g) crimping at least one threaded fastener to said inner panel;   (h) providing an outer panel for joining to said inner panel; and   (i) connecting said outer panel to said inner panels to provide said plural panel automotive member having threaded fasteners joined thereto.   
     
     
         21 . A process for producing plural panel automotive members having inner and outer panels connected to form said members, said inner panels having threaded fasteners securely crimped into said inner panels to provide means for bolting accessories to said automotive member, said inner panel formed by the process comprising:
 (a) providing a molten aluminum alloy consisting essentially of 2.7 to 3.6 wt. % Mg, 0.1 to 0.4 wt. % Mn, 0.02 to 0.2 wt. % Si, 0.05 to 0.25 wt. % Fe, 0.1 wt. % max. Cu, 0.25 wt. % max. Cr, 0.2 wt. % max. Zn, 0.15 wt. % max. Ti, the remainder aluminum, incidental elements and impurities;   (b) providing a continuous caster for continuously casting said molten aluminum alloy;   (c) casting said molten aluminum alloy into a slab having a thickness in the range of 0.2 to 2 inches thick, said slab containing Al—Fe, Al—Fe—Mn or Mg 2 Si intermetallic particles;   (d) hot rolling said slab into a hot rolled sheet product;   (e) cold rolling said hot rolled sheet product to a thickness in the range of 0.01 inch to 0.2 inch to provide a cold rolled sheet product;   (f) annealing said cold rolled sheet product to provide an annealed sheet product, said annealed sheet product having a tensile strength in the range of 28 to 35 ksi, a yield strength in the range of 12 to 17.5 ksi and an elongation greater than 19%, said annealed sheet product having a substantially uniform distribution or minimized striations of said intermetallic particles and have an average grain size in the range of about 15 to 20 μm;   (g) crimping at least one threaded fastener to said inner panel;   (h) providing an outer panel for joining to said inner panel; and   (i) connecting said outer panel to said inner panels to provide said plural panel automotive member having threaded fasteners joined thereto.   
     
     
         22 . A process for producing plural panel automotive members having inner and outer panels connected to form said members, said inner panels having threaded fasteners securely crimped into said inner panels to provide means for bolting accessories to said automotive member, said inner panel formed by the process comprising:
 (a) providing a molten aluminum alloy consisting essentially of 2.7 to 3.6 wt. % Mg, 0.1 to 0.4 wt. % Mn, 0.02 to 0.2 wt. % Si, 0.05 to 0.25 wt. % Fe, 0.1 wt. % max. Cu, 0.25 wt. % max. Cr, 0.2 wt. % max. Zn, 0.15 wt. % max. Ti, the remainder aluminum, incidental elements and impurities;   (b) providing a continuous caster for continuously casting said molten aluminum alloy;   (c) casting said molten aluminum alloy into a slab having a thickness in the range of 0.2 to 2 inches, said slab containing Al—Fe, Al—Fe—Mn or Mg 2 Si intermetallic particles;   (d) hot rolling said slab into a hot rolled sheet product, said hot rolling starting in a temperature range of 750° F. to 1000° F. and ending in a temperature range of 450° to 800° F.;   (e) annealing said hot rolled sheet product to provide an annealed sheet product;   (f) cold rolling said annealed sheet product to a thickness in the range of 0.01 inch to 0.2 inch;   (g) annealing said cold rolled sheet product to provide a cold rolled and annealed sheet product having a tensile strength in the range of 28 to 35 ksi, a yield strength in the range of 12 to 17.5 ksi and an elongation greater than 19%, said cold rolled and annealed sheet product having a substantially uniform distribution or minimized striations of said intermetallic particles and have an average grain size in the range of about 15 to 20 μm;   (h) forming the said annealed sheet at room temperature into said inner panel;   (i) crimping at least one threaded fastener to said inner panel;   (j) providing an outer panel for joining to said inner panel; and   (k) connecting said outer panel to said inner panels to provide said plural panel automotive member having threaded fasteners joined thereto.