High performance press-hardened steel

Abstract

A press-hardened steel component after hot forming including an alloy composition including carbon at a concentration of greater than or about 0.01 wt. % to less than or about 0.2 wt. %, chromium at a concentration of greater than or about 0.5 wt. % to less than or about 6 wt. %, manganese at a concentration of greater than or about 0.5 wt. % to less than or about 4.5 wt. %, silicon at a concentration of greater than or about 0.5 wt. % to less than or about 2.5 wt. %, and a balance of the alloy composition being iron, wherein the press-hardened steel component includes greater than or 90 volume % martensite and bainite, has an ultimate tensile strength of greater than or about 800 megapascals to less than or about 1,200 megapascals and a VDA 238-100 bending angle of greater than or about 60° to less than or about 80°.

What is claimed is: 
     
         1 . A press-hardened steel component after hot forming comprising:
 an alloy composition comprising:
 carbon (C) at a concentration of greater than or equal to about 0.01 wt. % to less than or equal to about 0.2 wt. %, 
 chromium (Cr) at a concentration of greater than or equal to about 0.5 wt. % to less than or equal to about 6 wt. %, 
 manganese (Mn) at a concentration of greater than or equal to about 0.5 wt. % to less than or equal to about 4.5 wt. %, 
 silicon (Si) at a concentration of greater than or equal to about 0.5 wt. % to less than or equal to about 2.5 wt. %, and 
   a balance of the alloy composition being iron (Fe), wherein the press-hardened steel component comprises greater than or equal to 90 volume % martensite and bainite, and has an ultimate tensile strength of greater than or equal to about 800 megapascals to less than or equal to about 1,200 megapascals and a VDA 238-100 bending angle of greater than or equal to about 60° to less than or equal to about 80°.   
     
     
         2 . The press-hardened steel component according to  claim 1 , wherein the alloy composition further comprises:
 molybdenum (Mo) at a concentration of greater than or equal to about 0.01 wt. % to less than or equal to about 0.8 wt. %,   niobium (Nb) at a concentration of less than or equal to about 0.8 wt. %, vanadium (V) at a concentration of less than or equal to about 0.8 wt. %, or a combination thereof less than or equal to about 0.8 wt. %,   boron (B) at a concentration of less than or equal to about 0.005 wt. %, nitrogen (N) at a concentration of less than or equal to about 0.008 wt. %, and nickel (Ni) at a concentration of less than or equal to about 5 wt. %.   
     
     
         3 . The press-hardened steel component according to  claim 2 , wherein the niobium (Nb) is at a concentration of greater than or equal to about 0.02 wt. % to less than or equal to about 0.04 wt. %. 
     
     
         4 . The press-hardened steel component according to  claim 1 , wherein the alloy composition comprises:
 Cr at a concentration of greater than or equal to about 1 wt. % to less than or equal to about 3 wt. %, and   Si at a concentration of greater than or equal to about 1 wt. % to less than or equal to about 2 wt. %.   
     
     
         5 . The press-hardened steel component according to  claim 1 , wherein the alloy composition comprises
 C at a concentration of greater than or equal to about 0.08 wt. % to less than or equal to about 0.12 wt. %,   Mn at a concentration of greater than or equal to about 1 wt. % to less than or equal to about 4.5 wt. %,   Cr at a concentration of greater than or equal to about 1 wt. % to less than or equal to about 3 wt. %, and   Si at a concentration of greater than or equal to about 1 wt. % to less than or equal to about 2 wt. %.   
     
     
         6 . The press-hardened steel component according to  claim 1 , further comprising a first surface layer comprising oxides and having a thickness of greater than or equal to about 0.01 μm to less than or equal to about 10 μm, the first surface layer being continuous. 
     
     
         7 . The press-hardened steel component according to  claim 6 , wherein the oxide of the first surface layer is enriched with Cr, and Si. 
     
     
         8 . The press-hardened steel component according to  claim 1 , wherein the press-hardened steel component is free of any applied surface coating. 
     
     
         9 . The press-hardened steel component according to  claim 8 , wherein the alloy composition has been subjected to a quench process. 
     
     
         10 . A press-hardened steel automotive component after hot forming comprising:
 an alloy matrix having an alloy composition comprising,
 carbon (C) at a concentration of greater than or equal to about 0.01 wt. % to less than or equal to about 0.2 wt. %, 
   chromium (Cr) at a concentration of greater than or equal to about 0.5 wt. % to less than or equal to about 6 wt. %,
 manganese (Mn) at a concentration of greater than or equal to about 0.5 wt. % to less than or equal to about 4.5 wt. %, 
 silicon (Si) at a concentration of greater than or equal to about 0.5 wt. % to less than or equal to about 2.5 wt. %, and
 a balance of the alloy composition being iron (Fe), wherein the alloy matrix comprises greater than or equal to 90 volume % martensite and bainite, 
 
   a continuous surface layer disposed directly on the alloy matrix, the continuous surface layer having a thickness of greater than or equal to about 0.01 μm to less than or equal to about 10 μm, and comprising an oxide enriched with chromium (Cr) and silicon (Si), wherein the press-hardened steel component has an ultimate tensile strength of greater than or equal to about 800 megapascals to less than or equal to about 1,200 megapascals, a VDA 238-100 bending angle of greater than or equal to about 60° to less than or equal to about 80°.   
     
     
         11 . The press-hardened steel automotive component according to  claim 10 , wherein the alloy composition further comprises
 molybdenum (Mo) at a concentration of greater than or equal to about 0.01 wt. % to less than or equal to about 0.8 wt. %,   niobium (Nb) at a concentration of less than or equal to about 0.8 wt. %, vanadium (V) at a concentration of less than or equal to about 0.8 wt. %, or a combination thereof less than or equal to about 0.8 wt. %,   boron (B) at a concentration of less than or equal to about 0.005 wt. %,   nitrogen (N) at a concentration of less than or equal to about 0.008 wt. %, and   nickel (Ni) at a concentration of less than or equal to about 5 wt. %.   
     
     
         12 . The press-hardened steel automotive component according to  claim 11 , wherein the niobium (Nb) is at a concentration of greater than or equal to about 0.02 wt. % to less than or equal to about 0.04 wt. %. 
     
     
         13 . The press-hardened steel automotive component according to  claim 10 , wherein the alloy matrix includes
 martensite and bainite at a concentration greater than or equal to about 90 vol. %,   ferrite at a concentration of less than or equal to 5 vol. %, and   austenite at a concentration of less than or equal to 10 vol. %.   
     
     
         14 . The press-hardened steel automotive component according to  claim 10 , wherein the alloy composition further comprises
 C at a concentration of greater than or equal to about 0.08 wt. % to less than or equal to about 0.12 wt. %,   Mn at a concentration of greater than or equal to about 1 wt. % to less than or equal to about 4.5 wt. %,   Cr at a concentration of greater than or equal to about 1 wt. % to less than or equal to about 3 wt. %, and   Si at a concentration of greater than or equal to about 1 wt. % to less than or equal to about 2 wt. %.   
     
     
         15 . The press-hardened steel automotive component according to  claim 10 , wherein the press-hardened steel automotive component is free of any applied surface coating. 
     
     
         16 . The press-hardened steel automotive component according to  claim 10 , wherein the press-hardened steel has an ultimate tensile strength (UTS) of greater than or equal to about 1,000 megapascals. 
     
     
         17 . A method of forming a press-hardened steel component; the method comprising:
 heating a blank of a steel alloy to a temperature above an upper critical temperature (Ac 3 ) of the alloy composition to form a heated blank comprising austenite, the upper critical temperature being greater than or equal to about 880° C. to less than or equal to about 950° C., wherein the steel alloy is uncoated and comprises:
 chromium (Cr) at a concentration of greater than or equal to about 0.5 wt. % to less than or equal to about 6 wt. %, 
 carbon (C) at a concentration of greater than or equal to about 0.1 wt. % to less than or equal to about 0.2 wt. %, 
 manganese (Mn) at a concentration of greater than or equal to about 0.5 wt. % to less than or equal to about 4.5 wt. %, 
 silicon (Si) at a concentration of greater than or equal to about 0.5 wt. % to less than or equal to about 2.5 wt. %, and 
 a balance of the alloy composition being iron; 
   stamping the heated blank into a predetermined shape to form a stamped component; and   quenching the stamped component at a constant rate to a temperature less than or equal to about a martensite finish (Mf) temperature of the steel alloy and greater than or equal to about room temperature to form the press-hardened steel component having a tensile strength of greater than or equal to about 800 megapascals to less than or equal to about 1,200 megapascals and a bend angle of greater than or equal to about 60° to less than or equal to about 80°,   wherein the method is free of a descaling step, and the press-hardened steel component is free of any applied coating.   
     
     
         18 . The method according to  claim 17 , wherein the quenching comprises decreasing the temperature of the stamped component at a rate of greater than or equal to about 20° C/s until the stamped object reaches a temperature below a martensite finish (Mf) temperature of the steel alloy for greater than or equal to about 120 seconds to less than or equal to about 1,000 seconds. 
     
     
         19 . The method according to  claim 18 , wherein the press-hardened steel component is free of any coating comprising zinc (Zn), aluminum (Al), silicon (Si), and combinations thereof. 
     
     
         20 . The method according to  claim 17 , wherein the method is free from pre-oxidizing the steel alloy, coating the stamped component, and shot blasting.