Super-tough steel and production method thereof

Abstract

A super-tough steel and a production method thereof. The present invention belongs to the field of steels and preparation thereof, and particularly relates to a super-tough steel for cryogenic services, and a production method thereof. The super-tough steel comprises the following elements in percentage by weight: 0.10% to 0.15% of C, and 29.5% to 31.5% of Mn, with the balance being Fe and inevitable impurities. The production method comprises the following steps: A1, smelting with argon protection, and electroslag remelting; A2, hot rolling or hot forging; A, annealing at 900° C. to 1100° C. for 1 hour, and quenching; and A4, cold rolling, annealing of the cold-rolled plate at 700° C.-1200° C. for 1 hour, and quenching after annealing. The steel is simple in composition and does not contain precious metals; and the steel has an average grain size of less than 30 microns, and is non-magnetic with complete face-centered cubic structure. The steel has outstanding performance at cryogenic temperatures, and its cryogenic impact energy exceeds all currently known metallic materials.

1 . A super-tough steel, characterized by comprising the following elements in percentage by weight: 0.10% to 0.15% of C, and 29.5% to 31.5% of Mn, with the balance being Fe and inevitable impurities. 
     
     
         2 . The steel according to  claim 1 , characterized in that the steel comprises, in percentage by weight, 0.11% of C, and 30% of Mn, with the balance being Fe and inevitable impurities. 
     
     
         3 . The steel according to  claim 1 , characterized in that the steel has an average grain size of less than 30 microns in microstructure. 
     
     
         4 . The steel according to  claim 3 , characterized in that the steel has an average grain size of 5.6 microns in microstructure. 
     
     
         5 . The steel according to  claim 1 , characterized in that the steel has an average impact energy of greater than 420 J at cryogenic temperature (liquid nitrogen temperature). 
     
     
         6 . A production method for the super-tough steel, comprising the following steps:
 A1, smelting, in percentage by weight, 0.10% to 0.15% of C, and 29.5% to 31.5% of Mn, with the balance being Fe and inevitable impurities in the presence of argon, and subjecting the obtained system to electroslag remelting;   A2, hot rolling or hot forging: heating ingots to a temperature of 1150° C. to 1250° C., and hot rolling or hot forging the ingots with an initial rolling temperature or initial forging temperature of ≥800° C. and a final rolling temperature or final forging temperature of ≥600° C., followed by air cooling, to obtain a hot rolled plate or hot forged plate of 20 to 40 mm;   A3, annealing the hot rolled plate or hot forged plate at a temperature of 900° C. to 1100° C. for 1 hour, and quenching the plate; and   A4, cold rolling the quenched steel plate with a cold rolling reduction of 50%-75% to obtain a cold rolled plate with a thickness of about 10 mm; and annealing the cold-rolled plate under a temperature of 700° C. to 1200° C. for 1 hour, and quenching the annealed plate.