Twinning/transformation induced plasticity high entropy steels and method of manufacturing the same

Abstract

A high entropy steel in which twinning and phase transformation are simultaneously performed, and a method of manufacturing the same, are provided. The high entropy steel includes three or more alloying elements selected from the following, by atomic percentage: iron (Fe) from 35% to 80%, nickel (Ni) from 5% to 35%, manganese (Mn) from 5% to 35%, cobalt (Co) from 5% to 35%, and chromium (Cr) from 5% to 35%

What is claimed is: 
     
         1 . A high entropy steel having excellent workability and hardening performance, comprising:
 three or more alloying elements selected from the following, by atomic percentage: iron (Fe) from 35% to 80%, nickel (Ni) from 5% to 35%, manganese (Mn) from 5% to 35%, cobalt (Co) from 5% to 35%, and chromium (Cr) from 5% to 35.   
     
     
         2 . The high entropy steel of  claim 1 , further comprising, by atomic %, one or more selected from carbon (C) from 0.01% to 5.0%, nitrogen (N) from 0.01% to 5.0%, boron (B) from 0.01% to 5.0%, silicon (Si) from 0.01% to 10%, copper (Cu) from 0.01% to 10%, vanadium (V) from 0.01% to 10%, and aluminum (Al) from 0.01% to 10%. 
     
     
         3 . The high entropy steel of  claim 1 , wherein stacking fault energy is 40 mJ/m 2  or less, and ‘an atomic size difference x an alloy composition % value’ is 0.05 or more. 
     
     
         4 . A method of manufacturing a high entropy steel having excellent workability and work hardening performance, the method comprising:
 preparing a metallic material including an three or more alloying elements selected from the following, by atomic percentage: iron (Fe) from 35% to 80%, nickel (Ni) from 5% to 35%, manganese (Mn) from 5% to 35%, cobalt (Co) from 5% to 35%, and chromium (Cr) from 5% to 35;   producing the prepared metallic material as molten alloy;   applying a homogenizing heat treatment on the alloy in the temperature range between 850° C. and 1250° C., and then cooling the alloy in the room temperature; and   after processing the cooled alloy, applying a second heat treatment where the alloy is maintained in the temperature range between 350° C. and 850° C. for 0.5 to 72 hours.   
     
     
         5 . The method of  claim 4 , wherein the high entropy steel further comprises, by atomic %, one or more selected from carbon (C) from 0.01% to 5.0%, nitrogen (N) from 0.01% to 5.0%, boron (B) from 0.01% to 5.0%, silicon (Si) from 0.01% to 10%, copper (Cu) from 0.01% to 10%, vanadium (V) from 0.01% to 10%, and aluminum (Al) from 0.01% to 10 
     
     
         6 . The method of  claim 4 , wherein the metallic material is produced as a molten alloy, using one method selected from casting, arc melting, powder metallurgy, thermal spray casting, thermal spray coating, spray coating, and 3D-printing. 
     
     
         7 . The method of  claim 4 , wherein the processing of the cooled alloy is performed using one of forging, extrusion, rolling and drawing.