Martensitic steels with 1700 to 2200 mpa tensile strength

Abstract

A martensitic steel alloy is provided. The martensitic steel alloy includes carbon from 0.22 to 0.36 wt. %, manganese from 0.5% to 2.0% wt. %, and chromium in an amount less than 0.10 wt. %. and a carbon equivalent C eq of less than 0.44 in which C eq =C+Mn/6+(Cr+Mo+V)/5+(Ni+Cu)/15. C eq is the carbon equivalent, C, Mn, Cr, Mo, V, Ni, and Cu are in wt. % of the elements in the alloy. The alloy has an ultimate tensile strength of at least 1700 MPa.

1 - 17 . (canceled) 
     
     
         18 . A martensitic steel alloy comprising:
 C from 0.22 to 0.36 wt. %;   Mn from 0.5% to 2.0% wt. %;   a carbon equivalent C eq  of less than 0.44 wherein:
 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; 
   an ultimate tensile strength of the alloy being at least 1700 MPa,   wherein Cr is 0 wt. %.   
     
     
         19 . The martensitic steel alloy of  claim 18 , wherein the alloy has an ultimate tensile strength of at least 1800 MPa. 
     
     
         20 . The martensitic steel alloy of  claim 18 , wherein the alloy has an ultimate tensile strength of at least 1900 MPa. 
     
     
         21 . The martensitic steel alloy of  claim 18 , wherein the alloy has an ultimate tensile strength of at least 2000 MPa. 
     
     
         22 . The martensitic steel alloy of  claim 18 , wherein the alloy has an ultimate tensile strength of at least 2100 MPa. 
     
     
         23 . The martensitic steel alloy of  claim 18 , wherein the alloy has an ultimate tensile strength between 1700 and 2200 MPa. 
     
     
         24 . The martensitic steel alloy of  claim 18 , wherein the alloy has a total elongation of at least 3.5%. 
     
     
         25 . The martensitic steel alloy of  claim 18 , wherein the alloy has a total elongation of at least 5%. 
     
     
         26 . The martensitic steel alloy of claim  1 , wherein the alloy is in the form of a cold rolled sheet, band or coil. 
     
     
         27 . The martensitic steel alloy of  claim 26 , wherein the cold rolled sheet, band or coil has a thickness of less than or equal to 1 mm. 
     
     
         28 . The martensitic steel alloy of  claim 18 , wherein said alloy contains about 0.2 wt. % silicon. 
     
     
         29 . The martensitic steel alloy of claim  1 , wherein said alloy further contains one or more of Nb, Ti, B, Al, N, S, P. 
     
     
         30 . The martensitic steel alloy of  claim 18 , wherein Cr+Mo+V is less than 0.10 wt. %. 
     
     
         31 . The martensitic steel alloy of  claim 18 , wherein Cr+Mo+V is 0 wt. %. 
     
     
         32 . The martensitic steel alloy of  claim 18 , wherein C is from 0.28 to 0.36 wt. % and Mn from 0.5% to 1.0% wt. %. 
     
     
         33 . The martensitic steel alloy of  claim 18 , wherein C is from 0.22 to 0.28 wt. % and Mn less than or equal to 2.0 wt. %. 
     
     
         34 . The martensitic steel alloy of  claim 18 , wherein C is from 0.28 to 0.36 wt. % and Mn is from 0.5% to 1.0% wt. %. 
     
     
         34 . The martensitic steel alloy of  claim 18 , wherein C is from 0.22 to 0.28 wt. % and Mn is less than or equal to 2.0 wt. %.