Method for producing stainless steel

Abstract

A method of suppressing embrittlement of stainless steel in a stainless steel production process comprising the steps of ⋅manufacturing stainless steel in a conventional stainless steel manufacturing process ⋅annealing the stainless steel in an annealing step ⋅cooling the steel in a cooling step or quenching the steel in a quenching step and ⋅applying a magnetic field to the stainless steel during the cooling or quenching step

1 . A method of suppressing embrittlement of stainless steel in a stainless steel production process comprising the steps of:
 manufacturing stainless steel in a conventional stainless steel manufacturing process;   annealing the stainless steel in an annealing step;   cooling the steel in a cooling step or quenching the steel in a quenching step; and   applying a magnetic field to the stainless steel   
       wherein the magnetic field is applied to the stainless steel during the cooling or quenching step. 
     
     
         2 . The method according to  claim 1 , wherein the stainless steel production process comprises
 melting a raw/scrap material for stainless steel production;   casting stainless steel into ingots, slabs, blooms or atomized metallic powder;   further processing the stainless steel by rolling, pressing or forming into billets, plates, sheets, strips, coils, bars, rods, wires, profiles and shapes, seamless and welded tubes and/or pipes, formed shapes, near net shape powder metallurgy and profiles.   
     
     
         3 . The method according to  claim 1 , wherein the raw material is melted in an electric arc furnace with or without vacuum oxygen decarburization. 
     
     
         4 . The method according to  claim 1 , wherein the stainless steel is tapped into a mould. 
     
     
         5 . The method according to  claim 1 , wherein the stainless steel is tapped into a copper mould. 
     
     
         6 . The method according to  claim 1 , wherein the stainless steel is continuously cast into slabs. 
     
     
         7 . The method according to  claim 1 , wherein the annealing step comprises raising the temperature of the steel to a temperature in excess of 900° C. for homogenization, softening, and dissolving secondary phases. 
     
     
         8 . The method according to  claim 1 , wherein the cooling or quenching step reduces the temperature to maintain the material properties of the steel. 
     
     
         9 . The method according to  claim 1  wherein the annealing step is carried out in batch furnaces for batch annealing or in-line annealing. 
     
     
         10 . The method according to  claim 1  wherein the cooling or quenching step reduces the temperature of the steel from the annealing temperature to a temperature below 350° C., particularly below 200° C., preferably 150° C. or below, suitably to room temperature either by a quenching step (batch quenching in water tanks or in-line spraying) or cooling step (as air cooling either by forced air or natural cooling). 
     
     
         11 . The method according to  claim 1 , wherein the magnetic field applied during quenching has a field strength in the range of >0.2 T, preferably >1.0 T, suitably 1.5 T to 3.0 T. 
     
     
         12 . The method according to  claim 1 , wherein the stainless steel is ferrite containing stainless steel or martensite containing stainless steel.