Martensitic stainless steel, method for the production of a semi-finished product from said steel, and cutting tool produced from the semi-finished product

Abstract

Martensitic stainless steel, characterized in that its composition consists of, in percentages by weight: 0.10%≤C≤0.45%; traces≤Mn≤1.0%; traces≤Si≤1.0%; traces≤S≤0.01%; traces≤P≤0.04%; 15.0%≤Cr≤18.%; traces≤Ni≤0.50%; traces≤Mo≤0.50%; traces≤Cu≤0.50%; traces≤V≤0.50%; traces≤Nb≤0.03%; traces≤Ti≤0.03%; traces≤Zr≤0.03%; traces≤Al≤0.010%; traces≤O≤0.0080%; traces≤Pb≤0.02%; traces≤Bi≤0.02%; traces≤Sn≤0.02%; 0.10%≤N≤0.20%; C+N≥0.25%; Cr+16N−5C≥16.0%; preferably 17Cr+500C+500N≤570%; the rest being iron and impurities resulting from the development. A method for the production of a semi-finished product from this martensitic stainless steel, and cutting tool produced from this semi-finished product.

1 - 9 . (canceled) 
     
     
         10 . A martensitic stainless steel, characterized in that its composition consists of, in weight percentages:
 0.10%≤C≤0.45%;   traces≤Mn≤1.0%;   traces≤Si≤1.0%;   traces≤S≤0.01%;   traces≤P≤0.04%;   15.0%≤Cr≤18.0%;   traces≤Ni≤0.50%;   traces≤Mo≤0.50%;   traces≤Cu≤0.50%;   traces≤V≤0.50%;   traces≤Nb≤0.03%;   traces≤Ti≤0.03%;   traces≤Zr≤0.03%;   traces≤Al≤0.010%;   traces≤O≤0.0080%;   traces≤Pb≤0.02%;   traces≤Bi≤0.02%;   traces≤Sn≤0.02%;   0.10%≤N≤0.20%;   C+N≥0.25%;   Cr+16N−5C≥16.0%;   the rest being iron and impurities resulting from the melting.   
     
     
         11 . The steel according to  claim 10 , wherein its microstructure includes at least 75% martensite. 
     
     
         12 . The steel according to  claim 10 , wherein 0.20%≤C≤0.38%. 
     
     
         13 . The steel according to  claim 12 , wherein 0.20%≤C≤0.35%. 
     
     
         14 . The steel according to  claim 12 , wherein 0.30%≤C≤0.35%. 
     
     
         15 . The steel according to  claim 10 , wherein traces≤Mn≤0.6%. 
     
     
         16 . The steel according to  claim 10 , wherein traces≤S≤0.005%. 
     
     
         17 . The steel according to  claim 10 , wherein 15.0%≤Cr≤17.0%. 
     
     
         18 . The steel according to  claim 17 , wherein 15.2%≤Cr≤17.0%. 
     
     
         19 . The steel according to  claim 18 , wherein 15.5%≤Cr≤16.0% 
     
     
         20 . The steel according to  claim 10 , wherein traces≤Mo≤0.01%. 
     
     
         21 . The steel according to  claim 20 , wherein traces≤Mo≤0.05%. 
     
     
         22 . The steel according to  claim 10 , wherein traces≤Cu≤0.3%. 
     
     
         23 . The steel according to  claim 10 , wherein traces≤V≤0.2%. 
     
     
         24 . The steel according to  claim 10 , wherein 0.15%≤N≤0.20%. 
     
     
         25 . The steel according to  claim 10 , wherein C+N≥0.30%. 
     
     
         26 . The steel according to  claim 25 , wherein C+N≥0.45%. 
     
     
         27 . The steel according to  claim 10 , wherein 17Cr+500C+500N≤570%. 
     
     
         28 . A method for producing a semi-finished product made from martensitic stainless steel, comprising:
 developing and pouring a semi-finished product from a steel having the composition according to  claim 10 ;   heating said semi-finished product to a temperature greater than or equal to 1000° C.;   hot rolling to obtain a sheet, bar or wire rod;   annealing said sheet, bar or wire rod at a temperature comprised between 700 and 900° C.; and   carrying out a shaping operation on said sheet, bar or wire rod.   
     
     
         29 . The method according to  claim 28 , wherein said semi-finished product is a sheet, and said shaping operation is a cold rolling. 
     
     
         30 . The method according to  claim 28 , wherein said semi-finished product is a bar or wire rod, and said shaping operation is a forging. 
     
     
         31 . A method for producing a semi-finished product made from martensitic stainless steel, comprising:
 developing and pouring a semi-finished product from a steel having the composition according to  claim 11 ;   heating said semi-finished product to a temperature greater than or equal to 1000° C.;   hot rolling to obtain a sheet, bar or wire rod;   annealing said sheet, bar or wire rod at a temperature comprised between 700 and 900° C.;   carrying out a shaping operation on said sheet, bar or wire rod;   austenitizing the shaped semi-finished product at a temperature between 950 and 1150° C.;   cooling at a speed of at least 15° C./s to a temperature of less than or equal to 20° C.; and   annealing at a temperature comprised between 100 and 300° C.   
     
     
         32 . The method according to  claim 28  further comprising:
 austenitizing the shaped semi-finished product at a temperature between 950 and 1150° C.; 
 cooling at a speed of at least 15° C./s to a temperature of less than or equal to 20° C.; and 
 undergoing a cryogenic treatment at a temperature from −220 to −50° C.; and 
 annealing at a temperature comprised between 100 and 300° C. 
 
     
     
         33 . A cutting tool comprising the semi-finished product prepared according to the method of  claim 28 . 
     
     
         34 . The cutting tool according to  claim 33 , wherein the cutting tool is a cutlery item including a knife blade, a food processor blade, a scalpel, or a scissor blade.