Martensitic steels with 1700-2200 mpa tensile strength

Abstract

Martensitic steel compositions and methods of production thereof. More specifically, the martensitic steels have tensile strengths ranging from 1700 to 2200 MPa. Most specifically, the invention relates to thin gage (thickness of ≦1 mm) ultra high strength steel with an ultimate tensile strength of 1700-2200 MPa and methods of production thereof.

What is claimed: 
     
         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 between 1700 and 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,   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 between 0.22 and 0.36 wt. % carbon. 
     
     
         13 . The martensitic steel alloy of  claim 12 , wherein said alloy contains between 0.22 and 0.28 wt. % carbon. 
     
     
         14 . The martensitic steel alloy of  claim 12 , wherein said alloy contains between 0.28 and 0.36 wt. % carbon. 
     
     
         15 . The martensitic steel alloy of  claim 12 , wherein said alloy contains between 0.5 and 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.