A steel sheet for cans has a chemical composition containing, by mass %, C: 0.015% or more and 0.150% or less, Si: 0.04% or less, Mn: 1.0% or more and 2.0% or less, P: 0.025% or less, S: 0.015% or less, Al: 0.01% or more and 0.10% or less, N: 0.0005% or more and less than 0.0050%, Ti: 0.003% or more and 0.015% or less, B: 0.0010% or more and 0.0040% or less, and the balance being Fe and inevitable impurities. The steel sheet has a microstructure including a ferrite phase as a main phase and at least one of a martensite phase and a retained austenite phase as a second phase, the total area fraction of the second phase being 1.0% or more, and the sheet has a tensile strength of 480 MPa or more, a total elongation of 12% or more, and a yield elongation of 2.0% or less.

A metal plate for laser processing (such as a stainless steel plate or a titanium plate) and preferably an austenitic stainless steel plate suitable for use as a metal mask or the like which undergoes fine processing with a laser has an average grain diameter d (μm) and a plate thickness t (μm) which satisfy the equation d≦0.0448.Math.t−1.28.

A method for producing a silicon steel normalizing substrate comprises steelmaking, hot rolling and normalizing steps. A normalizing furnace is used in the normalizing step, and along a moving direction of strip steel, the normalizing furnace sequentially comprises: a preheating section, a nonoxidizing heating section, a furnace throat, furnace sections for subsequent normalizing processing, and a delivery seal chamber. Furnace pressures of the normalizing furnace are distributed as follows: the furnace pressure of a downstream furnace section adjacent to the furnace throat along the moving direction of the strip steel is the highest, the furnace pressure decreases gradually from the furnace section with the highest furnace pressure to a furnace section in an inlet direction of the normalizing furnace, and the furnace pressure decreases gradually from the furnace section with the highest furnace pressure to a furnace section in an outlet direction of the normalizing furnace.

A method for producing a silicon steel normalizing substrate comprises steelmaking, hot rolling and normalizing steps. A normalizing furnace is used in the normalizing step, and along a moving direction of strip steel, the normalizing furnace sequentially comprises: a preheating section, a nonoxidizing heating section, a furnace throat, furnace sections for subsequent normalizing processing, and a delivery seal chamber. Furnace pressures of the normalizing furnace are distributed as follows: the furnace pressure of a downstream furnace section adjacent to the furnace throat along the moving direction of the strip steel is the highest, the furnace pressure decreases gradually from the furnace section with the highest furnace pressure to a furnace section in an inlet direction of the normalizing furnace, and the furnace pressure decreases gradually from the furnace section with the highest furnace pressure to a furnace section in an outlet direction of the normalizing furnace.

The present invention relates to a high-strength high-toughness steel plate and a method of manufacturing the steel plate. The steel plate contains the following chemical compositions, by weight, C: 0.03-0.06%, Si≦0.30%, Mn: 1.0-1.5%, P≦0.020%, S≦0.010%, Al: 0.02-0.05%, Ti: 0.005-0.025%, N≦0.006%, Ca≦0.005%, and more than one of Cr≦0.75%, Ni≦0.40%, Mo≦0.30%, other compositions being Ferrum and unavoidable impurities. The finished steel plate, with a thickness of 6-25 mm, has a yield strength of ≧700 MPa, an elongation A50 of ≧18%, Akv at −60° C. of ≧150 J and good cool bending property.

The present invention relates to a high-strength high-toughness steel plate and a method of manufacturing the steel plate. The steel plate contains the following chemical compositions, by weight, C: 0.03-0.06%, Si≦0.30%, Mn: 1.0-1.5%, P≦0.020%, S≦0.010%, Al: 0.02-0.05%, Ti: 0.005-0.025%, N≦0.006%, Ca≦0.005%, and more than one of Cr≦0.75%, Ni≦0.40%, Mo≦0.30%, other compositions being Ferrum and unavoidable impurities. The finished steel plate, with a thickness of 6-25 mm, has a yield strength of ≧700 MPa, an elongation A50 of ≧18%, Akv at −60° C. of ≧150 J and good cool bending property.

A high-strength cold-rolled steel sheet having a specified chemical composition and a microstructure including ferrite having an average crystal grain diameter of 2 μm or less in an amount of 10% to 25% in terms of volume fraction, retained austenite in an amount of 5% to 20% in terms of volume fraction, martensite having an average crystal grain diameter of 2 μm or less in an amount of 5% to 15% in terms of volume fraction, and the balance being a multi-phase structure including bainite and tempered martensite having an average crystal grain diameter of 5 μm or less, in which a relational expression, 0.35≦V2/V1≦0.75 (1), is satisfied, where V1 is a volume fraction of phases which are different from ferrite and V2 is a volume fraction of tempered martensite.

The present invention relates to pressure vessel steel having excellent hydrogen-induced cracking resistance, and a manufacturing method therefor. One embodiment of the present invention provides a pressure vessel steel having excellent hydrogen-induced cracking resistance, and a manufacturing method therefor, the steel comprising, by wt %, 0.2-0.3% of carbon (C), 0.05-0.50% of silicon (Si), 0.03% or less of manganese (Mn), 0.005-0.1% of aluminum (Al), 0.010% or less of phosphorus (P), 0.0015% or less of sulfur (S), 0.001-0.03% of niobium (Nb), 0.001-0.03% of vanadium (V), 0.001-0.03% of titanium (Ti), 0.01-0.20% of chromium (Cr), 0.01-0.15% of molybdenum (Mo), 0.01-0.50% of copper (Cu), 0.05-0.50% of nickel (Ni), 0.0005-0.0040% of calcium (Ca), and the balance of Fe and other inevitable impurities, wherein the average grain size of ferrite is 5-15 μm.

The present invention relates to pressure vessel steel having excellent hydrogen-induced cracking resistance, and a manufacturing method therefor. One embodiment of the present invention provides a pressure vessel steel having excellent hydrogen-induced cracking resistance, and a manufacturing method therefor, the steel comprising, by wt %, 0.2-0.3% of carbon (C), 0.05-0.50% of silicon (Si), 0.03% or less of manganese (Mn), 0.005-0.1% of aluminum (Al), 0.010% or less of phosphorus (P), 0.0015% or less of sulfur (S), 0.001-0.03% of niobium (Nb), 0.001-0.03% of vanadium (V), 0.001-0.03% of titanium (Ti), 0.01-0.20% of chromium (Cr), 0.01-0.15% of molybdenum (Mo), 0.01-0.50% of copper (Cu), 0.05-0.50% of nickel (Ni), 0.0005-0.0040% of calcium (Ca), and the balance of Fe and other inevitable impurities, wherein the average grain size of ferrite is 5-15 μm.

A gradient steel material with a high plastic surface layer and a high strength inner layer, and a manufacturing method are provided. Weight percentages of the components of the gradient steel material are: C≤0.15%, Si≤1%, Mn≤1.5%, and the balance of Fe and inevitable impurities, the surface layer of the steel material being ferrite, and the inner layer being ferrite+bainite. The manufacturing method therefor comprises: smelting, casting, rolling, and a heat treatment, wherein in the heat treatment step, a steel material is heated to an austenite temperature Ac3 or more and kept at said temperature for more than 3 min; thereafter, the material is cooled to a temperature range between Ar3 and Ar1 in a two-phase zone at a cooling rate of less than 0.5° C./s, and is then cooled to room temperature at a cooling rate of greater than 5° C./s. The present steel material does not need to be obtained by means of the compound preparation of different materials as only a single material is processed. At the same time, the composition of the steel material is simple. Although the internal and external microstructures are different, the difference is a gradual process, and the strength at the interface is good.