Steel for producing machine components formed from solid stock

Abstract

The invention relates to a steel and a processing method for producing machine components formed from solid stock, particularly for vehicle construction, having a primarily bainitic structure, characterized in that the chemical composition thereof has the following contents in weight percent: 0.10%≦C≦0.25%, 0.15%≦Si≦0.40%, 1.00%≦Mn≦1.50%, 1.00%≦Cr≦2.00%, 0.20%≦Ni≦0.40%, 0.05%≦Mo≦0.20%, 0.010%≦Nb≦0.040%, 0.05%≦V≦0.25%, 0.01%≦Al≦0.05%, 0.005%≦N≦0.025%, 0%≦B≦0.0050%, with the remainder being iron and the steel making-related accompanying elements and residual materials.

1 . Steel and processing method for the production of solidly formed machine components, particularly for vehicle construction, with a predominantly bainitic structure, wherein its chemical composition has the following contents, in weight percent: 
     
       
         
               
               
             
                   
                   
               
                   
                  0.10% ≦ C ≦ 0.25% 
               
                   
                  0.15% ≦ Si ≦ 0.40% 
               
                   
                  1.00% ≦ Mn ≦ 1.50% 
               
                   
                  1.00% ≦ Cr ≦ 2.00% 
               
                   
                  0.20% ≦ Ni ≦ 0.40% 
               
                   
                  0.05% ≦ Mo ≦ 0.20% 
               
                   
                 0.010% ≦ Nb ≦ 0.040% 
               
                   
                  0.05% ≦ V ≦ 0.25% 
               
                   
                  0.01% ≦ Al ≦ 0.05% 
               
                   
                 0.005% ≦ N ≦ 0.025% 
               
                   
                    0% ≦ B ≦ 0.0050% 
               
                   
                   
               
           
              
             
             
              
              
              
              
              
              
              
              
              
              
              
              
             
          
         
       
       whereby the remainder consists of iron and the melting-related accompanying elements and residual substances. 
     
   
   
       2 . Steel according to  claim 1 , wherein its chemical composition is such that the following applies: 
     
       
         
               
               
             
                   
                   
               
                   
                  0.10% ≦ C ≦ 0.20% 
               
                   
                  0.20% ≦ Si ≦ 0.30% 
               
                   
                  1.00% ≦ Mn ≦ 1.50% 
               
                   
                  1.50% ≦ Cr ≦ 2.00% 
               
                   
                  0.20% ≦ Ni ≦ 0.40% 
               
                   
                  0.05% ≦ Mo ≦ 0.20% 
               
                   
                 0.020% ≦ Nb ≦ 0.040% 
               
                   
                  0.05% ≦ V ≦ 0.20% 
               
                   
                  0.01% ≦ Al ≦ 0.05% 
               
                   
                 0.005% ≦ N ≦ 0.025% 
               
                   
                   
               
           
              
             
             
              
              
              
              
              
              
              
              
              
              
              
             
          
         
       
       whereby the remainder consists of iron and the melting-related accompanying elements and residual substances. 
     
   
   
       3 . Use of a steel according to  claim 2  for the production of machine components, particularly for vehicle construction, which components, after forging in a die and after accelerated, controlled cooling, have a bainitic structure, to a great extent, with precipitates of special carbides and/or nitrides. 
   
   
       4 . Component according to  claim 3 , wherein the yield strength after accelerated, controlled cooling from the forming heat amounts to above 620 N/mm 2 . 
   
   
       5 . Component according to  claim 4 , wherein the tensile strength after accelerated, controlled cooling from the forming heat amounts to between 800 N/mm 2  and 1100 N/mm 2 . 
   
   
       6 . Component according to  claim 5 , wherein the yield strength ratio after accelerated, controlled cooling from the forming heat amounts to above 70%. 
   
   
       7 . Component according to  claim 6 , wherein the ultimate elongation after accelerated, controlled cooling from the forming heat amounts to above 10%. 
   
   
       8 . Component according to  claim 7 , wherein the ultimate constriction after accelerated, controlled cooling from the forming heat amounts to above 40%. 
   
   
       9 . Component according to  claim 8 , wherein the notched-bar impact bending value (DVM notch, room temperature) after accelerated, controlled cooling from the forming heat amounts to above 25 J. 
   
   
       10 . Component according to  claim 9 , wherein the impact strength characteristics can be adjusted by means of stepped cooling, at a high cooling velocity, at first, and a holding stage in the bainitic range, or subsequent aging treatment. 
   
   
       11 . Component according to  claim 10 , wherein it is supposed to be suitable for case hardening and carbonitration. 
   
   
       12 . Component according to  claim 11 , wherein the mechanical properties both in the rolled pre-material and in the forged component can be adjusted by means of thermomechanical treatment.