Martensitic steels with 1700 to 2200 mpa tensile strength

Abstract

Martensitic steel compositions and methods of production thereof are provided. More specifically, a martensitic steel having tensile strengths ranging from 1700 to 2200 MPa are provided. Most specifically, the present invention provides thin gage (thickness of ≦1 mm) ultra high strength steel with an ultimate tensile strength of 1700 to 2200 MPa and methods of production thereof.

What is claimed is: 
     
         1 . A martensitic steel alloy, said alloy having an ultimate tensile strength of at least 1700 MPa. 
     
     
         2 . The martensitic steel alloy of  claim 1 , wherein said alloy has an ultimate tensile strength of at least 1800 MPa. 
     
     
         3 . The martensitic steel alloy of  claim 2 , wherein said alloy has an ultimate tensile strength of at least 1900 MPa. 
     
     
         4 . The martensitic steel alloy of  claim 3 , wherein said alloy has an ultimate tensile strength of at least 2000 MPa. 
     
     
         5 . The martensitic steel alloy of  claim 4 , wherein said alloy has an ultimate tensile strength of at least 2100 MPa. 
     
     
         6 . The martensitic steel alloy of  claim 1 , wherein said alloy has an ultimate tensile strength from 1700 to 2200 MPa. 
     
     
         7 . The martensitic steel alloy of  claim 1 , wherein said alloy has a total elongation of at least 3.5%. 
     
     
         8 . The martensitic steel alloy of  claim 7 , wherein said alloy has a total elongation of at least 5%. 
     
     
         9 . The martensitic steel alloy of  claim 1 , wherein said alloy is in the form of a cold rolled sheet, band or coil. 
     
     
         10 . The martensitic steel alloy of  claim 9 , wherein said a cold rolled sheet, band or coil has a thickness of less than or equal to 1 mm. 
     
     
         11 . The martensitic steel alloy of  claim 1 , wherein said alloy has a carbon equivalent of less than 0.44 using the formula:
   C eq =C+Mn/6+(Cr+Mo+V)/5+(Ni+Cu)/15   where C eq  is the carbon equivalent, and   C, Mn, Cr, Mo, V, Ni, and Cu are in wt. % of the elements in the alloy.   
     
     
         12 . The martensitic steel alloy of  claim 1 , wherein said alloy contains from 0.22 to 0.36 wt. % carbon. 
     
     
         13 . The martensitic steel alloy of  claim 12 , wherein said alloy contains from 0.22 to 0.28 wt. % carbon. 
     
     
         14 . The martensitic steel alloy of  claim 12 , wherein said alloy contains from 0.28 to 0.36 wt. % carbon. 
     
     
         15 . The martensitic steel alloy of  claim 12 , wherein said alloy contains from 0.5 to 2.0 wt. % manganese. 
     
     
         16 . The martensitic steel alloy of  claim 15 , wherein said alloy contains about 0.2 wt. % silicon. 
     
     
         17 . The martensitic steel alloy of  claim 15 , wherein said alloy further contains one or more of Nb, Ti, B, Al, N, S, P.