SHAPE MEMORY STAINLESS STEELS WITH RARE EARTH ELEMENTS Ce AND La

Abstract

Shape memory stainless steels with rare earth elements Cerium (Ce) and Lanthanum (La) are disclosed. In one embodiment, raw materials including Manganese (Mn), Silicon (Si), Chromium (Cr), Nickel (Ni), Carbon (C), Ce, La and Iron (Fe) are melted to form a molten alloy of the shape memory stainless steels with rare earth elements Ce and La. Further, the molten alloy is solidified to form an ingot. Furthermore, the ingot is subjected to nondestructive evaluation to assess internal soundness of the ingot. In addition, the evaluated ingot is homogenized to form homogenized shape memory stainless steels with rare earth elements Ce and La.

What is claimed is: 
     
         1 . Shape memory stainless steels with rare earth elements Cerium (Ce) and Lanthanum (La), which comprise, Manganese (Mn), Silicon (Si), Chromium (Cr), Nickel (Ni), Carbon (C), Ce, La and Iron (Fe). 
     
     
         2 . The shape memory stainless steels of  claim 1 , wherein the shape memory stainless steels with rare earth elements Ce and La comprise, by weight, about 15 to 17% of Mn, about 5 to 6% of Si, about 9 to 12% of Cr, about 8 to 10% of Ni, about 0.03 to 0.06% of C, about 0.10 to 0.50% of Ce, about 0.5 to 1.0% of La and the balance being Fe. 
     
     
         3 . The shape memory stainless steels of  claim 2 , wherein the shape memory stainless steels with rare earth elements Ce and La further comprise:
 unavoidable impurities.   
     
     
         4 . A method of forming shape memory stainless steels with rare earth elements Cerium (Ce) and Lanthanum (La), comprising:
 melting raw materials including Manganese (Mn), Silicon (Si), Chromium (Cr), Nickel (Ni), Carbon (C), Ce, La and Iron (Fe) to form a molten alloy of the shape memory stainless steels with rare earth elements Ce and La;   solidifying the molten alloy to form an ingot;   subjecting the ingot to nondestructive evaluation to assess internal soundness of the ingot; and   homogenizing the evaluated ingot to form homogenized shape memory stainless steels with rare earth elements Ce and La.   
     
     
         5 . The method of  claim 4 , wherein the shape memory stainless steels with rare earth elements Ce and La comprise, by weight, about 15 to 17% of Mn, about 5 to 6% of Si, about 9 to 12% of Cr, about 8 to 10% of Ni, about 0.03 to 0.06% of C, about 0.10 to 0.50% of Ce, about 0.5 to 1.0% of La and the balance being Fe. 
     
     
         6 . The method of  claim 4 , wherein homogenizing the evaluated ingot to form the homogenized shape memory stainless steels with rare earth elements Ce and La comprises:
 homogenizing the evaluated ingot by heating the evaluated ingot at a temperature in a range of about 1050° C. to 1150° C. for about 6 hours to form the homogenized shape memory stainless steels with rare earth elements Ce and La.   
     
     
         7 . The method of  claim 4 , wherein the nondestructive evaluation comprises nondestructive evaluation using gamma radiography. 
     
     
         8 . The method of  claim 4 , wherein melting the raw materials to form the molten alloy comprises:
 adding the raw materials; and   melting the added raw materials at a temperature of about 1600° C. to form the molten alloy.   
     
     
         9 . The method of  claim 8 , wherein melting the added raw materials at the temperature of about 1600° C. comprises:
 conventional melting of the added raw materials at the temperature of about 1600° C. 
 
     
     
         10 . The method of  claim 8 , wherein melting the added raw materials at the temperature of about 1600° C. comprises:
 vacuum induction melting of the added raw materials at the temperature of about 1600° C. 
 
     
     
         11 . The method of  claim 4 , wherein solidifying the molten alloy to form the ingot comprises:
 solidifying the molten alloy by cooling to form the ingot of a desired shape.   
     
     
         12 . The method of  claim 4 , further comprising:
 forming a semi-finished product from the homogenized shape memory stainless steels with rare earth elements Ce and La.   
     
     
         13 . The method of  claim 12 , wherein the semi-finished product comprises a rolled product or a forged product. 
     
     
         14 . The method of  claim 12 , further comprising:
 forming a desired component from the semi-finished product.   
     
     
         15 . The method of  claim 14 , wherein the desired component is an actuator for an aircraft engine, an automobile component and a pipe coupling.