The present invention provides a high-strength tin blackplate and a manufacturing method therefor.

The tin blackplate according to an exemplary embodiment of the present invention includes: by wt %, 0.03 to 0.09% of carbon (C); 0.2 to 0.4% of manganese (Mn); 0.01 to 0.06% of aluminum (Al); 0.15 to 0.45% of chromium (Cr); 0.05 to 0.25% of copper (Cu); 0.03 to 0.08% of titanium (Ti); and the balance of iron (Fe) and inevitable impurities, and has a yield strength of 570 to 700 MPa.

The present invention provides a high-strength tin blackplate and a manufacturing method therefor.

The tin blackplate according to an exemplary embodiment of the present invention includes: by wt %, 0.03 to 0.09% of carbon (C); 0.2 to 0.4% of manganese (Mn); 0.01 to 0.06% of aluminum (Al); 0.15 to 0.45% of chromium (Cr); 0.05 to 0.25% of copper (Cu); 0.03 to 0.08% of titanium (Ti); and the balance of iron (Fe) and inevitable impurities, and has a yield strength of 570 to 700 MPa.

A method for producing an austenitic heat resistant steel in which a difference between a content of Nb and an amount of Nb analyzed as extraction residues satisfies [0.170≤Nb−Nb.sub.ER≤0.480], the method including: a forming step of machining and forming a steel having a predetermined chemical composition into a product shape; a solution heat treatment step of performing, after the forming step, heat treatment under conditions including a heat treatment temperature satisfying [−250Nb+1200≤T≤−100Nb+1290] and a soaking time satisfying [405−0.3T≤t≤2475−1.5T]; and a cooling step of performing cooling after the solution heat treatment step.

A method for producing an austenitic heat resistant steel in which a difference between a content of Nb and an amount of Nb analyzed as extraction residues satisfies [0.170≤Nb−Nb.sub.ER≤0.480], the method including: a forming step of machining and forming a steel having a predetermined chemical composition into a product shape; a solution heat treatment step of performing, after the forming step, heat treatment under conditions including a heat treatment temperature satisfying [−250Nb+1200≤T≤−100Nb+1290] and a soaking time satisfying [405−0.3T≤t≤2475−1.5T]; and a cooling step of performing cooling after the solution heat treatment step.

An essentially lead free steel having improved machinability while reducing or eliminating lead (except for trace impurities) and without detriment of the material properties of the steel. The properties of the lead free steel are dependent on both the composition and method of manufacture. The improved lead free steel has, in percent by weight (wt-%): Carbon: 0.39-0.43%; Manganese: 0.75-1.00%; Silicon: 0.15-0.35%; Chromium: 0.80-1.05%; Molybdenum: 0.15-0.25%; at least one of Tellurium: 0.003-0.090 wt-%, Selenium: 0.080-0.2 wt-%, Sulfur: 0.065-0.09% wt-%, and Bismuth: 0.03-0.1 wt-%; and the balance being Fe and normally occurring scrap steel impurities. The hot-rolled lead-free steel product is subjected to a heat treatment at a first temperature for a first duration, at a second temperature for a second duration that is less than the first temperature, at a third temperature for a third time period that is greater than the second temperature, and subsequently cooling the steel product.

An essentially lead free steel having improved machinability while reducing or eliminating lead (except for trace impurities) and without detriment of the material properties of the steel. The properties of the lead free steel are dependent on both the composition and method of manufacture. The improved lead free steel has, in percent by weight (wt-%): Carbon: 0.39-0.43%; Manganese: 0.75-1.00%; Silicon: 0.15-0.35%; Chromium: 0.80-1.05%; Molybdenum: 0.15-0.25%; at least one of Tellurium: 0.003-0.090 wt-%, Selenium: 0.080-0.2 wt-%, Sulfur: 0.065-0.09% wt-%, and Bismuth: 0.03-0.1 wt-%; and the balance being Fe and normally occurring scrap steel impurities. The hot-rolled lead-free steel product is subjected to a heat treatment at a first temperature for a first duration, at a second temperature for a second duration that is less than the first temperature, at a third temperature for a third time period that is greater than the second temperature, and subsequently cooling the steel product.

Provided is a stainless steel sheet having a predetermined chemical composition, in which a total volume fraction of Cr-based carbides with a grain size of 2.0 μm or more is 10% or less.

Provided is a stainless steel sheet having a predetermined chemical composition, in which a total volume fraction of Cr-based carbides with a grain size of 2.0 μm or more is 10% or less.

The duplex stainless steel seamless pipe according to the present disclosure has the chemical composition described in the description and a microstructure consisting of 30 to 55% of ferrite, and austenite. In a square observation field of view region with sides of 250 μm including a center portion of the wall thickness and including a T direction and a C direction, a number of intersections NT which is a number of intersections between the line segment T1 to T4 described in the description and ferrite interfaces is 65 or more. A number of intersections NC which is a number of intersections between the line segments C1 to C4 described in the description and ferrite interfaces is 50 or more.

The duplex stainless steel seamless pipe according to the present disclosure has the chemical composition described in the description and a microstructure consisting of 30 to 55% of ferrite, and austenite. In a square observation field of view region with sides of 250 μm including a center portion of the wall thickness and including a T direction and a C direction, a number of intersections NT which is a number of intersections between the line segment T1 to T4 described in the description and ferrite interfaces is 65 or more. A number of intersections NC which is a number of intersections between the line segments C1 to C4 described in the description and ferrite interfaces is 50 or more.