Method for producing a motor vehicle component and motor vehicle component

Abstract

In a method for producing a motor vehicle component and a motor vehicle component produced according to the invention a steel sheet with a stacking fault energy between 10 and 40 mJ/m 2 and a manganese content between 10 and 30% is provided, which is prone to twin formation at room temperature and has at least regions with a predominantly austenitic microstructure. Regions of this steel sheet are first temperature treated to a temperature between +30° C. and −250° C. and subsequently cold formed.

What is claimed is: 
     
         1 . A method for producing a metallic motor vehicle component, comprising:
 providing a steel sheet with a manganese content from 10 to 30% and a stacking fault energy from 5 to 50 mJ/m 2 , in particular 10 to 40 mJ/m 2  wherein the material of the steel sheet at room temperature is prone to twin formation;   temperature treating at least regions of the steel sheet to a cold forming temperature between +30° C. and −250° C.;   forming the steel sheet to the motor vehicle component at substantially the cold forming temperature, wherein a martensite formation is induced at least in regions of the steel sheet component; and   retrieving the motor vehicle component from the forming tool.   
     
     
         2 . The method of  claim 1 , wherein the steel sheet is made of a steel alloy comprising the following alloy components in weight %: 
       
         
           
                 
                 
                 
               
                     
                     
                 
                     
                   Carbon (C) 
                   max. 2% 
                 
                     
                   Manganese (Mn) 
                   10 to 30% 
                 
                     
                   Silicone (Si) 
                   max. 6% 
                 
                     
                   Aluminum (Al) 
                   max 8% 
                 
                     
                   Niobium (Nb) 
                   max. 1% 
                 
                     
                   Vanadium (V) 
                   max 1% 
                 
                     
                   Titanium (Ti) 
                   max 1% 
                 
                     
                     
                 
             
                
               
               
                
                
                
                
                
                
                
                
               
            
           
         
         Remainder iron (Fe) and smelting related impurities. 
       
     
     
         3 . The method of  claim 1 , wherein the steel sheet is made of a TWIP steel. 
     
     
         4 . The method of  claim 1 , wherein the predominantly austenitic microstructure is transformed into a martensitic microstructure by the forming step. 
     
     
         5 . The method of  claim 1 , wherein the steel sheet has a stacking fault energy of 20 to 40 mJ/m 2 , and wherein the stacking fault energy is reduced to 15 to 20mJ/m 2  by the temperature treating of the steel sheet to the cold forming temperature. 
     
     
         6 . The method of  claim 1 , wherein liquid nitrogen is used for the temperature treatment. 
     
     
         7 . The method of  claim 1 , wherein the cold forming temperature is between +25° C. and −200° C., in particular in the range from +25° C. and −197° C. 
     
     
         8 . The method of  claim 1 , further comprising pre-stretching the steel sheet at cold forming temperature. 
     
     
         9 . The method of  claim 1 , wherein the temperature treatment of the steel sheet occurs in a cooling station and the cooled steel sheet is transferred into a forming tool. 
     
     
         10 . The method of  claim 9 , wherein the forming tool is cooled. 
     
     
         11 . The method of  claim 10 , wherein the steel sheet is cooled to the cold forming temperature in the forming tool. 
     
     
         12 . The method of  claim 1 , wherein at least a region of the steel sheet is pre-formed. 
     
     
         13 . The method according of  claim 13 , wherein the pre-forming occurs at or above room temperature. 
     
     
         14 . The method according of  claim 13 , wherein the preformed regions are formed to final dimension, and wherein the cold forming occurs subsequently in regions which are different from the pre-formed regions. 
     
     
         15 . A motor vehicle component produced according to the method of  claim 1 , wherein the motor vehicle component is made of a TWIP steel alloy, and wherein in at least sub-regions of the component have an essentially martensitic microstructure. 
     
     
         16 . The motor vehicle component of  claim 15 , comprising the following alloy components in weight %: 
       
         
           
                 
                 
                 
               
                     
                     
                 
                     
                   Carbon (C) 
                   max. 2% 
                 
                     
                   Manganese (Mn) 
                   10 to 30% 
                 
                     
                   Silicone (Si) 
                   max. 6% 
                 
                     
                   Aluminum (Al) 
                   max 8% 
                 
                     
                   Niobium (Nb) 
                   max. 1% 
                 
                     
                   Vanadium (V) 
                   max 1% 
                 
                     
                   Titanium (Ti) 
                   max 1% 
                 
                     
                     
                 
             
                
               
               
                
                
                
                
                
                
                
                
               
            
           
         
         Remainder iron (Fe) and smelting related impurities. 
       
     
     
         17 . The Motor vehicle component of  claim 15 , wherein the martensitic regions have an elongation at break R p02  between 500 and 1500 MPa, in particular between 700 and 1300 MPa and particularly preferably between 750 and 1000 MPa.