Method of manufacturing cast iron components for industrial equipment

Abstract

Methods of manufacturing cast iron components having increased hardness are disclosed herein. In an example embodiment, a method of forming a cast iron component for industrial equipment includes forming the cast iron component in a predetermined shape, machining the cast iron component, heat treating the cast iron component by raising the temperature of the cast iron component to an upper temperature, and cryogenically heat treating the cast iron component by lowering the temperature of the cast iron component to a lower temperature.

What is claimed is: 
     
         1 . A method of forming a cast iron component for industrial equipment, the method comprising:
 forming the cast iron component in a predetermined shape;   machining the cast iron component;   heat treating the cast iron component by raising the temperature of the cast iron component to an upper temperature; and   cryogenically heat treating the cast iron component by lowering the temperature of the cast iron component to a lower temperature.   
     
     
         2 . The method of  claim 1 , wherein
 the lower temperature is at or below 0° C.   
     
     
         3 . The method of  claim 1 , wherein
 the upper temperature is at or above 950° C.   
     
     
         4 . The method of  claim 1 , wherein
 cryogenically heat treating the cast iron component includes lowering the temperature of the cast iron component to between about −70° C. and −80° C.   
     
     
         5 . The method of  claim 1 , wherein
 cryogenically heat treating the cast iron component includes maintaining the cast iron component at about the lower temperature for between about 2 to 4 hours.   
     
     
         6 . The method of  claim 1 , including stress relieving the cast iron component before machining the cast iron component; 
     
     
         7 . The method of  claim 1 , wherein
 forming the cast iron component includes forming the cast iron component as a single piece.   
     
     
         8 . The cast iron component formed using the method of  claim 1 . 
     
     
         9 . A pump impeller formed as the cast iron component using the method of  claim 1 . 
     
     
         10 . A method of improving the hardness cast iron components for industrial equipment, the method comprising:
 forming a first cast iron component into a predetermined shape using a first liquid mixture, the first cast iron component having a first hardness;   increasing a concentration of at least one element in a second liquid mixture in comparison to the first liquid mixture;   forming a second cast iron component into the predetermined shape using the second liquid mixture, the second cast iron component having a second hardness greater than the first hardness; and   further increasing the second hardness of the second cast iron component by cryogenically heat treating the second cast iron component by lowering the temperature of the cast iron component to a lower temperature.   
     
     
         11 . The method of  claim 10 , wherein
 the at least one element is carbon.   
     
     
         12 . The method of  claim 10 , wherein
 the at least one element is molybdenum.   
     
     
         13 . The method of  claim 10 , including
 adding niobium to the second liquid mixture.   
     
     
         14 . The method of  claim 10 , including
 heat treating the first cast iron component by raising the temperature of the first cast iron component to a first temperature for a first duration, and   heat treating the second cast iron component by raising the temperature of the second cast iron component to a second temperature for a second duration, the second temperature being lower than the first temperature.   
     
     
         15 . The method of  claim 10 , including
 heat treating the first cast iron component by raising the temperature of the first cast iron component to a first temperature for a first duration, and   heat treating the second cast iron component by raising the temperature of the second cast iron component to a second temperature for a second duration, the second duration being less than the first duration.   
     
     
         16 . The method of  claim 10 , including
 machining the first cast iron component at a first location, and   machining the second cast iron component at the first location.   
     
     
         17 . The second cast iron component formed using the method of  claim 10 . 
     
     
         18 . A pump impeller formed as the second cast iron component using the method of  claim 1 . 
     
     
         19 . A method of improving the hardness cast iron components for industrial equipment, the method comprising:
 forming a first cast iron component into a predetermined shape using a first liquid mixture;   heat treating the first cast iron component by raising the temperature of the first cast iron component to a first temperature for a first duration, the first cast iron component having a first hardness after heat treatment;   forming a second cast iron component into the predetermined shape using a second liquid mixture;   heat treating the second cast iron component by raising the temperature of the second cast iron component to a second temperature for a second duration, the second cast iron component having a second hardness after heat treatment, the second hardness greater than the first hardness, at least one of the second temperature being lower than the first temperature and/or the second duration being less than the first duration; and   further increasing the second hardness of the second cast iron component by cryogenically heat treating the second cast iron component by lowering the temperature of the cast iron component to a lower temperature.   
     
     
         20 . The method of  claim 19 , including
 increasing a concentration of at least one element in a second liquid mixture in comparison to the first liquid mixture.