[Problem] To provide a grain-oriented electrical steel sheet which is further improved in terms of iron loss before magnetic domain control, while achieving a sufficient iron loss improvement effect even in the control of a heat-resistant magnetic domain where a sufficient iron loss improvement effect has not been achieved. [Solution] A grain-oriented electrical steel sheet according to one aspect of the present invention comprises abase steel sheet and a glass coating that is formed on the surface of the base steel sheet, and is characterized in that: the base steel sheet contains as chemical components, in mass %, 0.010% or less of C, from 2.00% to 4.00% of Si, from 0.05% to 1.00% of Mn, from 0.010% to 0.065% of Al, 0.004% or less of N and 0.010% or less of S, with the balance being made up of Fe and impurities; the oxygen concentration in the glass coating and the base steel sheet is 2,500 ppm or less; and if I.sub.Al_1 is the first peak intensity of Al and I.sub.Al_2 is the second peak intensity of Al in the concentration profile of Al, the relationship of mathematical formula (1) is satisfied.

I.sub.Al_1<I.sub.Al_2   Formula (1):

A grain-oriented electrical steel sheet of an embodiment of the present invention comprises Si: 1.0% to 7.0% and Y: 0.005% to 0.5% by wt %, and the remainder comprising Fe and other inevitable impurities, and 10 pieces or less of inclusions comprising Y and having a diameter of 30 nm to 5 μm per area of 1 mm.sup.2.

The present application relates to the technical field of die steel, and particularly discloses a hot working die steel with high thermal strength and high toughness and a manufacturing process thereof. The hot working die steel with high thermal strength and high toughness includes the following components in percentage by mass: 0.20-0.40% of carbon, 0.05-0.20% of silicon, 0.30-0.60% of manganese, 1.00-4.00% of chromium, 0.50-1.50% of molybdenum, 0.20-0.60% of vanadium, 0.60-1.00% of cobalt, 0.06-0.16% of titanium, 0.03-0.08% of yttrium, 0.03-0.08% of niobium, 0.005-0.012% of phosphorus, 0.003-0.008% of sulfur, and a balance of iron and inevitable impurities.

This high strength austenitic stainless steel having excellent resistance to hydrogen embrittlement includes, in terms of mass %, C: 0.2% or less, Si: 0.2% to 1.5%, Mn: 0.5% to 2.5%, P: 0.06% or less, S: 0.008% or less, Ni: 10.0% to 20.0%, Cr: 16.0% to 25.0%, Mo: 3.5% or less, Cu: 3.5% or less, N: 0.01% to 0.50%; and O: 0.015% or less, with the balance being Fe and unavoidable impurities, in which an average size of precipitates is 100 nm or less and an amount of the precipitates is 0.001% to 1.0% in terms of mass %.

A raw blank for vacuum carburization is provided. The raw blank for vacuum carburization has a chemical composition containing, by mass, C: 0.13 to 0.28%, Si: 0.01 to 1.20%, Mn: 0.10 to 1.50%, P: 0.030% or less, S: 0.050% or less, Cr: 0.30 to 2.20%, Al: 0.027 to 0.090%, N: 0.0060 to less than 0.0140%, and, as an optional element, Mo: 0.60% or less, the remainder being Fe and unavoidable impurities, and satisfying the following formula (1). AlN precipitates having an equivalent circle diameter of 100 nm or more exist at 1.5 pieces/100 μm.sup.2 or less in a cross section of the raw blank.

Al×N≤0.00090  (1)

It is noted that element symbols in the formula (1) denote a value of content (% by mass) of each element.

To provide a steel and a manufacturing method thereof that can contribute to achieving both high strength and hydrogen embrittlement resistance. The steel has a chemical composition represented by: C: 0.15% to 0.35%; Si: 0.8% to 2.5%; Mn: 0.8% to 2.5%; Al: 0.03% to 2.0%; N: 0.002% to 0.010%; P: 0.01% or less; S: 0.01% or less; O: 0.01% or less; B: 0.0001% to 0.005%; Nb: 0.0% to 0.05%; Ti: 0.0% to 0.2%; V 0.0% to 0.05%; Mo: 0.0% to 1.0%; Cr: 0.0% to 1.0%; Ni: 0.01% to 1.0%; Cu: 0.05% to 1.0%; at least one of Ca, Mg and REM: 0.0005% to 0.01%; and the balance: Fe and impurities, and has a martensite phase or/and a bainite phase in which ε-carbide is dispersedly precipitated.

Extrados structural element made from an aluminum, copper and lithium alloy and method for manufacturing same. An alloy with composition (in wt %) 4.2-5.2 Cu, 0.9-1.2 Li, 0.1-0.3 Ag, 0.1-0.25 Mg, 0.08-0.18 Zr, 0.01-0.15 Ti, an Fe and Si content level less than or equal to 0.1% each, and other element with content level less than or equal to 0.05% each and 0.15% in total, is poured, homogenized, deformed hot, placed in a solution at a temperature of at least 515° C., pulled from 0.5 to 5% and annealed. The combination of magnesium, copper and manganese content with the temperature in solution can reach an advantageous elasticity under compression limit. Products having a thickness of at least 12 mm have, in the longitudinal direction, an elasticity under compression limit of at least 645 MPa and an elongation of at least 7%.

Extrados structural element made from an aluminum, copper and lithium alloy and method for manufacturing same. An alloy with composition (in wt %) 4.2-5.2 Cu, 0.9-1.2 Li, 0.1-0.3 Ag, 0.1-0.25 Mg, 0.08-0.18 Zr, 0.01-0.15 Ti, an Fe and Si content level less than or equal to 0.1% each, and other element with content level less than or equal to 0.05% each and 0.15% in total, is poured, homogenized, deformed hot, placed in a solution at a temperature of at least 515° C., pulled from 0.5 to 5% and annealed. The combination of magnesium, copper and manganese content with the temperature in solution can reach an advantageous elasticity under compression limit. Products having a thickness of at least 12 mm have, in the longitudinal direction, an elasticity under compression limit of at least 645 MPa and an elongation of at least 7%.

A quench and temper steel alloy is disclosed having the following composition in weight percent. TABLE-US-00001 C 0.1-0.4 Mn 0.1-1.0 Si 0.1-1.2 Cr 9.0-12.5 Ni 3.0-4.3 Mo   1-2 Cu 0.1-1.0 Co   1-4 W  0.2 max. V 0.1-0.6 Ti  0.1 max. Nb up to 0.01 Ta up to 0.01 Al   0-0.25 N 0.1-0.35 Ce 0.006 max. La 0.006 max.
The balance of the alloy is iron and the usual impurities found in similar grades of quench and temper steels intended for similar use or service, including not more than about 0.01% phosphorus and not more than about 0.010% sulfur. A quenched and tempered steel article made from this alloy is also disclosed. Further disclosed is a method of making the alloy.

A method of preparing an engine valve is provided. The method includes hot forging a heat resistant steel at 1,150 to 1,250° C. to mold a valve, aging the molded valve and hollowed-out processing the aging valve. Additionally, the method includes nitride-heating the hollow valve and grinding a surface of a neck of the nitride-heated valve to remove a nitride layer.