Stainless steel for cutlery and method of manufacturing the same

Abstract

The present invention has the ultimate purpose of obtaining cutlery having marked characteristics such as high hardness and high toughness, and provides an intermediate material, an annealed material, and a cold-rolled steel strip for stainless steel for cutlery, and a method for manufacturing them to achieve the purpose. Provided is an intermediate material for stainless steel for cutlery, the intermediate material being a material after hot rolling but before annealing, having a composition, in terms of % by mass, of from 0.46 to 0.72% C, from 0.15 to 0.55% Si, from 0.45 to 1.00% Mn, from 12.5 to 13.9% Cr, from 0 to 1.5% Mo, from 0 to 0.012% B, and the balance being Fe and impurities; and wherein a ratio of a diffraction peak area from an fcc phase (a sum total of diffraction peak areas from (200) plane, (220) plane, and (311) plane) to a diffraction peak area from a bcc phase (a sum total of diffraction peak areas from (200) plane and (211) plane) (the diffraction peak area from the fcc phase/the diffraction peak area from the bcc phase) is 30 or less in an X-ray diffraction of a vertical section.

1 . An intermediate material for stainless steel for cutlery, the intermediate material being a material after hot rolling but before annealing, having a composition, in terms of % by mass, of from 0.46 to 0.72% C, from 0.15 to 0.55% Si, from 0.45 to 1.00% Mn, from 12.5 to 13.9% Cr, from 0 to 1.5% Mo, from 0 to 0.012% B, and the balance being Fe and impurities; and wherein a ratio of a diffraction peak area from an fcc phase (a sum total of diffraction peak areas from (200) plane, (220) plane, and (311) plane) to a diffraction peak area from a bcc phase (a sum total of diffraction peak areas from (200) plane and (211) plane) (the diffraction peak area from the fcc phase/the diffraction peak area from the bee phase) is 30 or less in an X-ray diffraction of a vertical section. 
     
     
         2 . The intermediate material for stainless steel for cutlery according to  claim 1 , wherein the content of B is from 0.0005 to 0.0050%. 
     
     
         3 . A method of manufacturing an intermediate material for stainless steel for cutlery, the intermediate material being a material after hot rolling but before annealing, the method comprising: heating a material, having a composition, in terms of % by mass, of from 0.46 to 0.72% C, from 0.15 to 0.55% Si, from 0.45 to 1.00% Mn, from 12.5 to 13.9% Cr, from 0 to 1.5% Mo, from 0 to 0.012% B, and the balance being Fe and impurities, to from 1100 to 1250° C., and hot rolling the material at a hot rolling end temperature of from 700 to 1000° C.; thereby manufacturing the intermediate material, wherein a ratio of a diffraction peak area from an fcc phase (a sum total of diffraction peak areas from (200) plane, (220) plane, and (311) plane) to a diffraction peak area from a bcc phase (a sum total of diffraction peak areas from (200) plane and (211) plane) (the diffraction peak area from the fcc phase/the diffraction peak area from the bcc phase) is 30 or less in an X-ray diffraction of a vertical section. 
     
     
         4 . The method of manufacturing an intermediate material for stainless steel for cutlery according to  claim 3 , wherein the content of is from 0.0005 to 0.0050%. 
     
     
         5 . A method of manufacturing an annealed material for stainless steel for cutlery, the method comprising subjecting the intermediate material for stainless steel for cutlery manufactured by the method according to  claim 3  to annealing at from 800 to 860° C. for from 1 to 100 hours. 
     
     
         6 . A method of manufacturing a cold-rolled steel strip for stainless steel for cutlery, the method comprising subjecting the annealed material for stainless steel for cutlery manufactured by the method according to  claim 5  to cold rolling and annealing, thereby manufacturing a cold-rolled steel strip with a thickness of less than 1.0 mm. 
     
     
         7 . A method of manufacturing an annealed material for stainless steel for cutlery, the method comprising subjecting the intermediate material for stainless steel for cutlery manufactured by the method according to  claim 4  to annealing at from 800 to 860° C. for from 1 to 100 hours. 
     
     
         8 . A method of manufacturing a cold-rolled steel strip for stainless steel for cutlery, the method comprising subjecting the annealed material for stainless steel for cutlery manufactured by the method according to  claim 7  to cold rolling and annealing, thereby manufacturing a cold-rolled steel strip with a thickness of less than 1.0 mm.