Method of determining a composition of a steel alloy for use in a low-alloy high-strength steel

Abstract

A method of determining a composition of a steel alloy includes minimizing a presence of AlN by satisfying the following condition: Al×N<5×10 3 (weight %), minimizing a formation of cementite by satisfying the following condition: Si+Al>4×C (weight %), wherein an Al content is selected in a range of 0.05 to 3.00 in weight %, wherein a N content is selected in a range of 0.001-0.025 in weight %, wherein a Si content is selected in a range of 0.25-4.00 in weight %, wherein a C content is selected in a range of 0.1-0.70 in weight %.

What is claimed is: 
     
         1 . A method of determining a composition of a steel alloy, comprising:
 minimizing a presence of AlN by satisfying the following condition:
   Al×N<5×10 −3  (weight %)
 
   minimizing a formation of cementite by satisfying the following condition:
   Si+Al>4×C (weight %),
 
   wherein an Al content is selected in a range of 0.05 to 3.00 in weight %,   wherein a N content is selected in a range of 0.001-0.025 in weight %,   wherein a Si content is selected in a range of 0.25-4.00 in weight %,   wherein a C content is selected in a range of 0.1-0.70 in weight %.   
     
     
         2 . The method of  claim 1 , further comprising decelerating a ferritic transformation by controlled addition of chromium in a range of at least 0.10 to 2.00 weight %. 
     
     
         3 . The method of  claim 1 , further comprising controlling a mechanical-technical property of the composition by satisfying the condition:
   (35×C)+(10×Mn)−Si−(5×Al)+Cr>13/{dot over ( T )}+10,
   wherein a Mn content is selected in a range of 1.00-3.00 weight %.   
     
     
         4 . The method of  claim 1 , further comprising controlling a kinetic of a baintic transformation by satisfying the condition:
   400×exp[(−7×C)−(4×Mn)+8Al+3]/{dot over ( T )}>1,
   wherein a Mn content is selected in a range of 1.00-3.00 weight %.   
     
     
         5 . The method of  claim 1 , further comprising controlling a marteniste start temperature in accordance with the following condition:
   525−(350×C)−(45×Mn)−(16×Mo)−(5×Al)<<400,
   wherein a Mn content is selected in a range of 1.00-3.00 weight %, and   wherein a Mo content is selected at a maximum of 5.50 weight %.   
     
     
         6 . The method of  claim 1 , further comprising controlling a relationship of ferrite and austenite formers in accordance with the following condition:
   C+Si/6+Mn/4+(Cr+Mo)/3>1,   wherein a Mn content is selected in a range of 1.00-3.00 weight %%, and   wherein a Mo content is selected at a maximum of 5.50 weight %.   
     
     
         7 . The method of  claim 1 , further comprising maintaining an average distance of residual austenite lamellas to less than 750 nm. 
     
     
         8 . The method of  claim 1 , further comprising maintaining an average distance of residual austenite lamellas to less than 500 nm.