Steel Shell for a Suction Roll and a Method of Producing a Steel Product

Abstract

A suction roll shell having a plurality of through holes is made of a stainless ferrite-austenite steel having a micro-structure essentially consisting of 35-65% by volume of ferrite and 35-65% by volume of austenite. The steel has a composition containing, among other things, 0.005-0.07 C and 0.15-0.30 N, in % by weight.

1 - 19 . (canceled)  
   
   
       20 . A suction roll shell with a plurality of through holes, wherein the shell is made of a stainless ferrite-austenite steel having a micro-structure essentially consisting of 35-65% by volume of ferrite and 35-65% by volume of austenite, and having a chemical composition containing 0.005-0.07 C, 0.1-2.0 Si, 3-8 Mn, 19-23 Cr, 0.5-1.7 Ni, 0.15-0.30 N, in % by weight.  
   
   
       21 . A suction roll shell according to  claim 20  wherein the steel contains 
 a) optionally Mo and/or W at a total content of no more than 1.0 (Mo+W/2)    b) optionally Cu up to a maximum of 1.0 Cu, balance being iron and impurities, and that for the ferrite and austenite formers in the alloy, i.e. the chromium and nickel equivalents, the following conditions are true:    c) 20<Cr eq <24.5    d) 10<Ni eq , where      e) Cr eq =Cr+1.5 Si+Mo+2 Ti+0.5 Nb  f) Ni eq =Ni+0.5 Mn+30 (C+N)+0.5 (Cu+Co).    
   
   
       22 . A suction roll shell according to  claim 20 , wherein the steel contains 0.02-0.05 C.  
   
   
       23 . A suction roll shell according to  claim 20 , wherein the steel contains 0.18-0.26 N.  
   
   
       24 . A suction roll shell according to  claim 20 , wherein the steel contains 20-23 Cr.  
   
   
       25 . A suction roll shell according to  claim 20 , wherein the steel contains 0.8-1.70 Ni.  
   
   
       26 . A suction roll shell according to  claim 25 , wherein the steel contains 1.35-1.7 Ni.  
   
   
       27 . A suction roll shell according to  claim 20 , wherein the steel contains 0.22 N, 21.5 Cr, 1.5 Ni, 0.3 Mo, 5 Mn, no more than 0.04 C, and preferably 0.3 Cu and preferably 0.7 Si.  
   
   
       28 . A suction roll, comprising a suction roll shell according to  claim 20 .  
   
   
       29 . A method of producing a steel product, comprising: 
 providing a steel workpiece, and    working of the workpiece by cutting operation,    wherein the steel of the workpiece is a stainless ferrite-austenite steel having a micro-structure essentially consisting of 35-65% by volume of ferrite and 35-65% by volume of austenite, and having a chemical composition containing 0.005-0.07 C, 0.1-2.0 Si, 3-8 Mn, 19-23 Cr, 0.5-1.7 Ni, 0.15-0.30 N, in % by weight.    
   
   
       30 . A method according to  claim 29 , wherein the steel contains 
 a) optionally Mo and/or W at a total content of no more than 1.0 (MO+W/2)    b) optionally Cu up to a maximum of 1.0 Cu, balance being iron and impurities, and that for the ferrite and austenite formers in the alloy, i.e. the chromium and nickel equivalents, the following conditions are true:    c) 20<Cr eq <24.5    d) 10<Ni eq , where      e) Cr eq =Cr+1.5 Si+Mo+2 Ti+0.5 Nb  f) Ni eq =Ni+0.5 Mn+30 (C+N)+0.5 (Cu+Co).    
   
   
       31 . A method according to  claim 30 , wherein the steel contains 0.02-0.05 C.  
   
   
       32 . A method according to  claim 30 , wherein the steel contains 0.18-0.26 N.  
   
   
       33 . A method according to  claim 30 , wherein the steel contains 20-23 Cr.  
   
   
       34 . A method according to  claim 30 , wherein the steel contains 0.8-1.70 Ni.  
   
   
       35 . A method according to  claim 30 , wherein the steel contains 0.22 N, 21.5 Cr, 1.5 Ni, 0.3 Me, 5 Mn and no more than 0.04 C.  
   
   
       36 . A method according to  claim 29 , wherein the cutting operation comprises drilling of at least one through hole.  
   
   
       37 . A method according to  claim 29 , wherein the cutting operation comprises turning.  
   
   
       38 . A method according to  claim 36 , wherein drilling of at least one through hole takes place after a preceding turning step.