Martensitic Stainless Steel and Production Method Therefor

Abstract

A martensitic stainless steel for use in tableware, knives, scissors and the like, containing in % by weight, 0.10 to 0.50% carbon and 11 to 16% chromium, and a production method therefore. A production method for mid-carbon martensitic stainless steel in a strip-casting device comprising a pair of rolls rotating in opposite directions, edge dams respectively provided to both sides of the rolls so as to form a molten steel pool, and a meniscus shield for supplying inert nitrogen gas to the upper surface of the molten steel pool, wherein a stainless-steel thin sheet is produced by supplying a molten stainless steel of the above composition to the molten steel pool via a nozzle from a tundish, and a hot-rolled annealed strip is produced to a rolling reduction of 5 to 40% using in-line rollers, and relates to martensitic stainless steel produced by the production method

1 . A production method for a martensitic stainless steel, wherein, in a strip-casting device comprising a pair of rolls rotating in opposite directions, edge dams respectively provided to both sides of the rolls so as to form a molten steel pool, and a meniscus shield for supplying inert nitrogen gas to the upper surface of the molten steel pool, a stainless-steel thin sheet is produced by supplying a molten stainless steel containing, as percentages by weight, 1.10 to 0.50% carbon and 11 to 16% chromium, to the molten steel pool via a nozzle from a tundish, and a hot-rolled annealed strip is produced to a rolling reduction of 5 to 40% using in-line rollers. 
     
     
         2 . The production method of  claim 1 , wherein the martensitic stainless steel contains, as percentages by weight, 0.1 to 1.0% silicon (Si), 0.1 to 1.0% manganese (Mn), over 0 to 0.1% nickel (Ni), over 0 to 0.04 sulfur (S), and over 0 to 0.05 phosphorus (P), and Fe and other unavoidable impurities as remnants. 
     
     
         3 . The production method of  claim 1 , wherein a hot-rolled annealed sheet is produced by performing batch annealing on the hot-rolled annealed strip at a temperature of 700 to 950° C. under a reducing gas atmosphere. 
     
     
         4 . The production method of  claim 3 , wherein the hot-rolled annealed strip has a hardness difference of 90 Hv or less between a carbide segregation portion and a non-segregation portion at a sectional portion in the thickness direction thereof when measuring their Vickers hardness values with a load of 100 g. 
     
     
         5 . The production method of  claim 3 , wherein the thickness of the carbide segregation portion is 20 μm or less at the sectional portion in the thickness direction of the hot-rolled annealed strip. 
     
     
         6 . A martensitic stainless steel produced by means of a production method, wherein, in a strip-casting device comprising a pair of rolls rotating in opposite directions, edge dams respectively provided to both sides of the rolls so as to form a molten steel pool, and a meniscus shield for supplying inert nitrogen gas to the upper surface of the molten steel pool, a stainless-steel thin sheet is produced by supplying a molten stainless steel containing, as percentages by weight, 1.10 to 0.50% carbon and 11 to 16% chromium, to the molten steel pool via a nozzle from a tundish, and a hot-rolled annealed strip is produced to a rolling reduction of 5 to 40% using in-line rollers. 
     
     
         7 . The martensitic stainless steel of  claim 6 , wherein the martensitic stainless steel contains, as percentages by weight, 0.1 to 1.0% silicon (Si), 0.1 to 1.0% manganese (Mn), over 0 to 0.1% nickel (Ni), over 0 to 0.04 sulfur (S), and over 0 to 0.05 phosphorus (P), and Fe and other unavoidable impurities as remnants. 
     
     
         8 . The martensitic stainless steel of  claim 6 , wherein a hot-rolled annealed sheet is produced by performing batch annealing on the hot-rolled annealed strip at a temperature of 700 to 950° C. under a reducing gas atmosphere. 
     
     
         9 . The martensitic stainless steel of  claim 8 , wherein the hot-rolled annealed strip has a hardness difference of 90 Hv or less between a carbide segregation portion and a non-segregation portion at a sectional portion in the thickness direction thereof when measuring their Vickers hardness values with a load of 100 g. 
     
     
         10 . The martensitic stainless steel of  claim 8 , wherein the thickness of the carbide segregation portion is 20 μm or less at the sectional portion in the thickness direction of the hot-rolled annealed strip. 
     
     
         11 . The martensitic stainless steel of  claim 6 , wherein the stainless steel is a thin sheet of which thickness is 1 to 5 mm. 
     
     
         12 . The martensitic stainless steel of  claim 7 , wherein the stainless steel is a thin sheet of which thickness is 1 to 5 mm. 
     
     
         13 . The martensitic stainless steel of  claim 8 , wherein the stainless steel is a thin sheet of which thickness is 1 to 5 mm. 
     
     
         14 . The martensitic stainless steel of  claim 9 , wherein the stainless steel is a thin sheet of which thickness is 1 to 5 mm. 
     
     
         15 . The martensitic stainless steel of  claim 10 , wherein the stainless steel is a thin sheet of which thickness is 1 to 5 mm.