Steel alloy

Abstract

A cast steel alloy comprising carbon (0.8 to 2.0%), chromium (4 to 15%), silicon (0.68 to 2.0%), manganese (0.6 to 1.2%) and nickel (1.5 to 4%) that exhibits exceptional hardness and tensile strength and is useful for a wide range of high wear resistance applications including in the mining, excavation and agriculture industries.

What is claimed is: 
     
         1 . A cast steel alloy comprising iron and the following:
 a) carbon in the amount of 0.8 to 2.0% by weight of the alloy;   b) chromium in the amount of 4 to 15% by weight of the alloy;   c) silicon in the amount of 0.68 to 2.0% by weight of the alloy;   d) manganese in the amount of 0.6 to 1.2% by weight of the alloy; and   e) nickel in the amount of 1.5 to 4% by weight of the alloy.   
     
     
         2 . An alloy as claimed in  claim 1 , the carbon is present in the amount of 1.2 to 1.4% by weight of the alloy. 
     
     
         3 . An alloy as claimed in  claim 1 , the chromium is present in the amount of 10 to 12% by weight of the alloy. 
     
     
         4 . An alloy as claimed in  claim 1 , the silicon is present in the amount of 1.0 to 1.2% by weight of the alloy. 
     
     
         5 . An alloy as claimed in  claim 1 , the manganese is present in the amount of 0.95 to 1.05% by weight of the alloy. 
     
     
         6 . An alloy as claimed in  claim 1 , the nickel is present in the amount of 1.9 to 2.2% by weight of the alloy. 
     
     
         7 . An alloy as claimed in  claim 1 , further comprising any one or more of:
 a) aluminium in the range of 0 to 0.15% by weight of the alloy;   b) molybdenum in the range of 0 to 2.4% by weight of the alloy; and   c) tungsten in the range of 0 to 0.5% by weight of the alloy.   
     
     
         8 . An alloy as claimed in  claim 1 , further comprising any one or more of vanadium, copper, cobalt, niobium, phosphorus, and sulfur. 
     
     
         9 . An alloy as claimed in  claim 1 , comprising:
 a) carbon in the amount of 1.42% by weight of the alloy;   b) chromium in the amount of 11.67% by weight of the alloy;   c) silicon in the amount of 1.28% by weight of the alloy;   d) manganese in the amount of 0.98% by weight of the alloy;   e) nickel in the amount of 2.15% by weight of the alloy; and   f) molybdenum in the amount of 0.50% by weight of the alloy;   
       with the remainder of the alloy comprising one or more of vanadium, copper, cobalt, niobium, phosphorus, and sulfur. 
     
     
         10 . An alloy as claimed in  claim 1 , which has a Brinell hardness of 340 BHN to 420 BHN. 
     
     
         11 . An alloy as claimed in  claim 1 , which has a Rockwell hardness of 35 to 45 HRC. 
     
     
         12 . An alloy as claimed in  claim 1 , which has a tensile strength of 400 to 500 MPa. 
     
     
         13 . A process for preparing a cast alloy as claimed in  claim 1  comprising the steps:
 i) preparing molten iron; 
 ii) adding chromium, silicon, manganese and nickel and mixing to form an homogenous melt; 
 iii) deoxidising the melt; and 
 iv) allowing the melt to cool and form the alloy. 
 
     
     
         14 . A process as claimed in  claim 13 , further comprising heat treatment of the alloy. 
     
     
         15 . A process as claimed in  claim 14 , wherein the alloy is normalised by heating to 900° C. for approximately 3 hours then allowed to cool to ambient temperature. 
     
     
         16 . A process as claimed in  claim 14 , wherein the alloy is quenched by heating to 900° C. for approximately 3 hours then submersed in air, oil or water. 
     
     
         17 . An alloy prepared by a process as claimed in  claim 14 , which has a Brinell hardness of 550 to 650 BHN. 
     
     
         18 . An alloy prepared by a process as claimed in  claim 14 , which has a Rockwell hardness of 50 to 65 HRC. 
     
     
         19 . An alloy prepared by a process as claimed in  claim 14 , which has a tensile strength of 700 to 800 MPa.