Ultra high strength body and chassis components

Abstract

A structural component for an automotive vehicle formed from a single-piece of steel material and having a closed, complex cross-section with increased strength, for example a strength of greater than 650 MPa, and thus improved performance, is provided. The structural component typically has an elongation of greater than 5%. The structural component is formed by expanding a boron-containing steel material, for example heating or hydroforming a tube of the steel material. The boron-containing steel material expands by least 2% during the forming process and thus achieves the closed, complex cross-section, while also achieving the high strength. In addition, the structural component can be formed with zones of varying thickness, strength, hardness, elongation, and/or other varying properties to achieve the desired performance.

1 . A method of manufacturing a structural component, comprising the steps of:
 providing a tube surrounding a hollow opening and extending between opposite ends, the tube being formed of a steel material including boron; and   expanding the steel material.   
     
     
         2 . The method of  claim 1 , wherein the expanding step includes disposing the tube between a pair of dies and injecting water under pressure into the hollow opening of the tube. 
     
     
         3 . The method of  claim 1 , wherein the expanding step includes heating the steel material to a temperature greater than 400° C. 
     
     
         4 . The method of  claim 1 , wherein the steel material expands by at least 2% when heated to a temperature greater than 400° C. or when the hollow opening is filled with water under pressure. 
     
     
         5 . The method of  claim 1 , wherein the steel material expands by greater than 10% and up to 50% when heated to a temperature greater than 400° C. or when the hollow opening is filled with water under pressure. 
     
     
         6 . The method of  claim 1 , wherein the expanding step includes increasing the area of the cross-sectional opening between the opposite ends. 
     
     
         7 . The method of  claim 1 , wherein the expanding step includes varying the thickness of the tube between the opposite ends. 
     
     
         8 . The method of  claim 1 , wherein the steel material of at least one zone of the tube has a yield strength of greater than 550 MPa and a tensile strength of greater than 650 MPa after the expanding step. 
     
     
         9 . A structural component, comprising:
 a steel material surrounding a hollow opening and extending between opposite ends;   the steel material containing boron; and   a cross-section of the steel material varying between the opposite ends.   
     
     
         10 . The structural component of  claim 9 , wherein the steel material has a yield strength of greater than 550 MPa and a tensile strength of greater than 650 MPa. 
     
     
         11 . The structural component of  claim 9 , wherein at least one of the thickness of the structural component and the cross-sectional area of the hollow opening varies between the opposite ends. 
     
     
         12 . The structural component of  claim 9 , wherein at least one of the strength, hardness, elongation, and ductility of the structural component varies between the opposite ends. 
     
     
         13 . The structural component of  claim 9 , wherein the steel material includes carbon in an amount of 0.19 to 0.25 percent by weight (wt. %), silicon in an amount up to 0.40 wt. %, manganese in an amount of 1.10 to 1.40 wt. %, phosphorous in an amount up to 0.025 wt. %, sulfur in an amount up to 0.015 wt. %, aluminum in an amount up to 0.08 wt. %, nitrogen in an amount up to 0.01 wt. %, chromium in an amount up to 0.30 wt. %, and boron in an amount of 0.0008 to 0.0050 wt. %, based on the total weight of the steel material. 
     
     
         14 . The structural component of  claim 9 , wherein the steel material includes carbon in an amount of 0.27 to 0.32 percent by weight (wt. %), silicon in an amount of 0.15 to 0.35 wt. %, manganese in an amount of 1.15 to 1.40 wt. %, phosphorous in an amount up to 0.023 wt. %, sulfur in an amount up to 0.010 wt. %, aluminum in an amount up to 0.080 wt. %, nitrogen in an amount up to 0.010 wt. %, chromium in an amount of 0.10 to 0.25 wt. %, titanium in an amount of 0.015 to 0.045 wt. %, and boron in an amount of 0.0015 to 0.0040 wt. %, based on the total weight of the steel material. 
     
     
         15 . The structural component of  claim 9 , wherein the steel material includes carbon in an amount of 0.36 to 0.40 percent by weight (wt. %), silicon in an amount of 0.15 to 0.35 wt. %, manganese in an amount of 1.20 to 1.40 wt. %, phosphorous in an amount up to 0.020 wt. %, sulfur in an amount up to 0.010 wt. %, aluminum in an amount up to 0.060 wt. %, nitrogen in an amount up to 0.010 wt. %, chromium in an amount of 0.10 to 0.25 wt. %, titanium in an amount of 0.015 to 0.045 wt. %, and boron in an amount of 0.0015 to 0.0045 wt. %, based on the total weight of the steel material. 
     
     
         16 . The method of  claim 1 , wherein at least one of the thickness of the structural component and the cross-sectional area of the hollow opening varies between the opposite ends. 
     
     
         17 . The method of  claim 1 , wherein at least one of the strength, hardness, elongation, and ductility of the structural component varies between the opposite ends. 
     
     
         18 . The method of  claim 1 , wherein the steel material includes carbon in an amount of 0.19 to 0.25 percent by weight (wt. %), silicon in an amount up to 0.40 wt. %, manganese in an amount of 1.10 to 1.40 wt. %, phosphorous in an amount up to 0.025 wt. %, sulfur in an amount up to 0.015 wt. %, aluminum in an amount up to 0.08 wt. %, nitrogen in an amount up to 0.01 wt. %, chromium in an amount up to 0.30 wt. %, and boron in an amount of 0.0008 to 0.0050 wt. %, based on the total weight of the steel material. 
     
     
         19 . The method of  claim 1 , wherein the steel material includes carbon in an amount of 0.27 to 0.32 percent by weight (wt. %), silicon in an amount of 0.15 to 0.35 wt. %, manganese in an amount of 1.15 to 1.40 wt. %, phosphorous in an amount up to 0.023 wt. %, sulfur in an amount up to 0.010 wt. %, aluminum in an amount up to 0.080 wt. %, nitrogen in an amount up to 0.010 wt. %, chromium in an amount of 0.10 to 0.25 wt. %, titanium in an amount of 0.015 to 0.045 wt. %, and boron in an amount of 0.0015 to 0.0040 wt. %, based on the total weight of the steel material. 
     
     
         20 . The method of  claim 1 , wherein the steel material includes carbon in an amount of 0.36 to 0.40 percent by weight (wt. %), silicon in an amount of 0.15 to 0.35 wt. %, manganese in an amount of 1.20 to 1.40 wt. %, phosphorous in an amount up to 0.020 wt. %, sulfur in an amount up to 0.010 wt. %, aluminum in an amount up to 0.060 wt. %, nitrogen in an amount up to 0.010 wt. %, chromium in an amount of 0.10 to 0.25 wt. %, titanium in an amount of 0.015 to 0.045 wt. %, and boron in an amount of 0.0015 to 0.0045 wt. %, based on the total weight of the steel material.