Manufacturing method of steel in which an element of treatment gas is dissolved and diffused

Abstract

A manufacturing method of steel in which an element of the treatment gas is dissolved and diffused includes heating the steel, making a treatment gas contact a surface of the steel such that an element of the treatment gas dissolves and diffuses from the surface of the steel into a surface layer thereof, and reducing a concentration of the treatment gas near a non-treatment surface that is a portion of the surface of the steel.

What is claimed is: 
     
         1 . A manufacturing method of steel in which an element of a treatment gas is dissolved and diffused, comprising:
 heating the steel;   making the treatment gas contact a surface of the steel such that the element of the treatment gas dissolves and diffuses from the surface of the steel into a surface layer thereof; and   reducing a concentration of the treatment gas near a non-treatment surface that is a portion of the surface of the steel.   
     
     
         2 . The manufacturing method according to  claim 1 , wherein
 the concentration of the treatment gas near the non-treatment surface is reduced by pyrolyzing the treatment gas.   
     
     
         3 . The manufacturing method according to  claim 2 , wherein
 the steel is arranged inside a heating furnace, the steel is heated, and the pyrolyzing of the treatment gas is performed by a pyrolysis heater,   the manufacturing method further comprising:   arranging the pyrolysis heater facing the non-treatment surface of the steel inside the heating furnace.   
     
     
         4 . The manufacturing method according to  claim 2 , wherein
 the steel is arranged inside a heating furnace, the steel is heated, and the pyrolyzing of the treatment gas is performed by a pyrolysis heater,   the manufacturing method further comprising:   dividing a space inside of the heating furnace into a treatment space and a non-treatment space by the pyrolysis heater;   arranging the non-treatment surface of the steel in the non-treatment space;   flowing the treatment gas into the treatment space; and   pyrolyzing treatment gas that heads from the treatment space toward the non-treatment space by the pyrolysis heater.   
     
     
         5 . The manufacturing method according to  claim 3 , further comprising:
 supplying the treatment gas into the heating furnace; and   interrupting the supply of the treatment gas into the heating furnace and discharging the treatment gas from the heating furnace, wherein   supplying the treatment gas into the heating furnace and interrupting the supply of the treatment gas into the heating furnace and discharging the treatment gas from the heating furnace are repeated.   
     
     
         6 . The manufacturing method according to  claim 4 , wherein
 supplying the treatment gas into the heating furnace; and   interrupting the supply of the treatment gas into the heating furnace and discharging the treatment gas from the heating furnace, wherein   supplying the treatment gas into the heating furnace and interrupting the supply of the treatment gas into the heating furnace and discharging the treatment gas from the heating furnace are repeated.   
     
     
         7 . The manufacturing method according to  claim 5 , wherein
 in interrupting the supply of the treatment gas into the heating furnace and discharging the treatment gas from the heating furnace, heating of the pyrolysis heater is interrupted.   
     
     
         8 . The manufacturing method according to  claim 6 , wherein
 in interrupting the supply of the treatment gas into the heating furnace and discharging the treatment gas from the heating furnace, heating of the pyrolysis heater is interrupted.