Press hardened steel with increased toughness and method for production

Abstract

A method for processing a press hardenable steel includes first heating a slab of the press hardenable steel. The slab is heated to a re-heat furnace temperature of approximately 2300° F. The slab is subjected to rolling into a steel sheet having a predetermined thickness. The temperature of the slab during rolling corresponds to a rolling temperature that is greater than or equal to 1600° F. The steel sheet is coiled. The temperature of the steel sheet during coiling corresponds to a coiling temperature of approximately 1050° F.

What is claimed is: 
     
         1 . A method for processing a press hardenable steel, the method comprising:
 (a) heating a slab of the press hardenable steel to a re-heat furnace temperature of approximately 2300° F.;   (b) rolling the slab into a steel sheet having a predetermined thickness, wherein the temperature of the slab during rolling corresponds to a rolling temperature that is greater than or equal to about 1600° F. (871° C.); and   (c) coiling the steel sheet, wherein the temperature of the steel sheet during coiling corresponds to a coiling temperature of approximately 1050° F.   
     
     
         2 . The method of  claim 1 , wherein the rolling step includes a rough rolling operation and a finish rolling operation. 
     
     
         3 . The method of  claim 2 , wherein the temperature of the slab during the rough rolling operation is greater than or equal to 2000° F. 
     
     
         4 . The method of  claim 2 , wherein the temperature of the slab during the finish rolling operation is greater than or equal to about 1600° F. (871° C.). 
     
     
         5 . The method of  claim 2 , wherein the temperature of the slab during the rough rolling operation is approximately 2000° F. 
     
     
         6 . The method of  claim 2 , wherein the temperature of the slab during the finish rolling operation is approximately 1600° F. to 1700° F. 
     
     
         7 . The method of  claim 1 , further comprising hot stamping at least a portion of the steel sheet after coiling the steel sheet. 
     
     
         8 . The method of  claim 1 , further comprising cooling the press hardenable steel from the re-heat furnace temperature to the rolling temperature at a first cooling rate, and cooling the press hardenable steel from the rolling temperature to the coiling temperature at a second cooling rate, wherein the second cooling rate is greater than the first cooling rate. 
     
     
         9 . The method of  claim 1 , wherein the step of cooling the press hardenable steel from the rolling temperature to the coiling temperature is performed using a run-out table accelerated cooling method. 
     
     
         10 . The method of  claim 1 , wherein the press hardenable steel has a composition comprising:
 0.10 to 0.50% Carbon;   0.00 to 0.005% Boron;   0.0 to 0.50% Chromium;   0.75 to 3.0% Manganese;   0.090% or less Niobium;   0.02 to 1.50% Silicon;   0.0 to 0.80% Aluminum;   0.0 to 0.060% Titanium;   0.0 to 0.50% Molybdenum;   0.0 to 0.60% Nickel; and   the balance including iron and impurities.