High strength and toughness low carbon nanostructured bainitic steel and preparation method thereof

Abstract

A nanostructured bainitic steel of low carbon comprising of the following components in percentage by mass: Carbon—(0.24-0.28%), Manganese—(1.8-2%), Silicon—(2-2.5%), Nickel—(1.5-1.8%), Molybdenum—(0.2-0.25%), Chromium—(0.2-0.25%), Aluminium—(0.2-0.25%), and Cobalt—(0.45-0.5%) and the balance being Iron and unavoidable impurities and a method for preparation thereof.

What is claimed is: 
     
         1 . A nanostructured bainitic steel of low carbon comprising of the following components in percentage by mass: Carbon—(0.24-0.28%), Manganese—(1.8-2%), Silicon—(2-2.5%), Nickel—(1.5-1.8%), Molybdenum—(0.2-0.25%), Chromium—(0.2-0.25%), Aluminium—(0.2-0.25%), and Cobalt—(0.45-0.5%) and the balance being Iron and unavoidable impurities. 
     
     
         2 . The nanostructured bainitic steel of low carbon comprising of the following components in percentage by mass: Carbon—0.26% Manganese—1.9% Silicon—2.49% Nickel—1.6% Molybdenum—0.21% Chromium—0.21% Aluminium—0.2% Cobalt 0.49% and the balance being Iron and unavoidable impurities. 
     
     
         3 . A method for the preparation of the nanostructured bainite steel of low carbon as claimed in preceeding claims comprises the following steps:
 austenitization of steel at 945-955° C. for 15-20 minutes;   a first stage of isothermal transformation of austenitized steel comprising the elements as claimed in  claim 1 , at 350-360° C. for 20-25 minutes; and   a second stage of isothermal transformation at temperature of 250-255° C. for at least 6 hours.