A nitrided packaging steel in the form of a flat steel product and method for producing a nitrided packaging steel with a carbon content of 10-1000 ppm and uncombined nitrogen, dissolved in the steel, of more than 100 ppm. The nitriding is performed in two stages: a first stage, in which a molten steel is nitrided to a nitrogen content of at most 160 ppm by introducing a nitrogen-containing gas and/or a nitrogen-containing solid into the molten steel, and a second stage, in which a flat steel product produced from the nitrided molten steel by cold rolling is treated with a nitrogen-containing gas in order to increase further the amount of uncombined nitrogen in the flat steel product. The second stage is performed in an annealing furnace, in which the flat steel product is at the same time annealed in a recrystallizing manner. The packaging steels produced are distinguished by great strength, in excess of 600 MPa, and good elongation to fracture, regularly in excess of 5%, as well as by good forming properties.

A steel for high-strength aluminum clad substrate, comprising the following chemical elements by mass percent: C: 0.008-0.02%, 0<Si≤0.005%, Mn: 0.25-0.5%, P: 0.018-0.03%, Al≤0.005%, N: 0.0040-0.010%, Ti: 0.02-0.04%, O: 0.02-0.050%, and the balance being Fe and other inevitable impurities. The manufacturing method therefor comprises the steps of: (1) smelting and casting; (2) reheating: reheating a casting blank to 1180° C.-1250° C.; (3) rough rolling; (4) finish rolling; (5) coiling; and (6) cooling to room temperature. The steel for high-strength aluminum clad substrate has good strength and good plasticity.

The steel sheet has a steel microstructure containing ferrite: 6% to 90% by area, a microstructure composed of one or more of upper bainite, fresh martensite, tempered martensite, lower bainite, and retained γ: 10% to 94% by area in total, and retained γ: 3% to 20% by volume, a ratio (S.sub.UB/S.sub.2nd)×100(%) of an area ratio S.sub.UB of an upper bainite with a width in the range of 0.8 to 7 μm, a length in the range of 2 to 15 μm, and an aspect ratio of 2.2 or more in contact with retained γ.sub.UB with a grain width in the range of 0.17 to 0.80 μm and an aspect ratio in the range of 4 to 25 to an area ratio S.sub.2nd of the microstructure composed of one or more of upper bainite, fresh martensite, tempered martensite, lower bainite, and retained γ ranges from 2.0% to 15%.

A non-oriented electrical steel sheet includes C: 0 to 0.0050 mass %, Si: 0.50 to 2.70 mass %, Mn: 0.10 to 3.00 mass %, Al: 1.00 to 2.70 mass %, and P: 0.050 to 0.100 mass %. In the non-oriented electrical steel sheet, Al/(Si+Al+0.5×Mn) is 0.50 to 0.83, Si+Al/2+Mn/4+5×P is 1.28 to 3.90, Si+Al+0.5×Mn is 4.0 to 7.0, the ratio of the intensity of {100} plane I{100} to the intensity of {111} plane I{111} is 0.50 to 1.40, the specific resistance is 60.0×10.sup.−8 Ω.Math.m or higher at room temperature, and the thickness is 0.05 mm to 0.40 mm.

Steel for coiled tubing with a low yield ratio and ultra-high strength and a preparation method thereof, wherein the chemical composition of the steel in mass percentage is: C: 0.05-0.16%, Si: 0.1-0.9%, Mn: 1.25-2.5%, P≤0.015%, S≤0.005%, Cr: 0.51-1.30%, Nb: 0.005-0.019%, V: 0.010-0.079%, Ti: 0.01-0.03%, Mo: 0.10-0.55%, Cu: 0.31-0.60%, Ni: 0.31-0.60%, Ca: 0.0010-0.0040%, Al: 0.01-0.05%, N≤0.008%, and the rest being Fe and inevitable impurity elements. The chemical composition combines the technologies of low temperature finishing rolling and low temperature coiling to obtain an MA constituent+bainite+ferrite multiphase structure. The steel has a low yield ratio and ultra-high strength with the following specific properties: yield strength≥620 MPa, tensile strength≥750 MPa, elongation≥11%, and yield ratio≤0.83, and is suitable for manufacturing coiled tubing with ultra-high strength having a grade of 110 ksi or higher.

The invention is intended to provide a duplex stainless steel and a method for manufacturing same. A duplex stainless steel pipe is also provided. A duplex stainless steel of the present invention has a specific composition, and has a microstructure containing an austenitic phase and a ferrite phase. The duplex stainless steel satisfies the following contents for C, Si, Mn, Cr, Mo, Ni, N, Cu, and W in the formula (1) below, and has a yield strength YS of 655 MPa or more, and an absorption energy vE.sub.−10 of 40 J or more as measured by a Charpy impact test at a test temperature of −10° C.

0.55[% C]−0.056[% Si]+0.018[% Mn]−0.020[% Cr]−0.087[% Mo]+0.16[% Ni]+0.28[% N]−0.506[% Cu]−0.035[% W]+[% Cu*F]≤0.94  (1)

A non-oriented electrical steel sheet is produced by subjecting a steel slab containing, in mass %, C: not more than 0.0050%, Si: 1.0 to 6.5%, Mn: 0.05 to 2.0%, S: not more than 0.0050%, Al: not more than 0.01%, N: not more than 0.0050%, Ti: not more than 0.0030%, Nb: not more than 0.0030% and O: not more than 0.0050% to a hot rolling, a cold rolling and a finish annealing, the finish annealing conducted under conditions that a soaking temperature T (° C.) satisfies the following equation (1):

[00001]$\begin{array}{cc}\frac{\left(8000+400\times \mathrm{Si}\left(\mathrm{mass}\%\right)\right)}{\{\left(-\log \left(\mathrm{Al}\left(\mathrm{mass}\%\right)\times N\left(\mathrm{mass}\%\right)\right)+1.7+0.2\times \mathrm{Si}\left(\mathrm{mass}\%\right)\right\}}-273.15\le T\le 1200,& \left(1\right)\end{array}$

and an atmosphere in the finish annealing is a mixed gas composed of one or more selected from nitrogen, hydrogen and noble gas with a nitrogen content of not more than 50 vol % and a dew point of not higher than −20° C., whereby a non-oriented electrical steel sheet achieving a high magnetic flux density and a low iron loss is produced.

The present invention relates to tool, die, piece or mould, which, in use, is able to transfer heat out, in and/or through it, and where high mechanical and/or tribological loads have to be withstand at least in one area of the component. The invention also relates to several steel compositions with high fracture toughness and/or high resistance to decarburization comprised in the tool, die, piece or mould of the invention.

A double oriented electrical steel sheet according to an embodiment of the present invention includes: in wt %, Si at 2.0 to 4.0 wt %, Al at 0.01 to 0.04 wt %, S at 0.0004 to 0.002 at %, Mn at 0.05 to 0.3 wt %, N at 0.008 wt % or less (excluding 0 wt %), C at 0.005 wt % or less (excluding 0 wt %), P at 0.005 to 0.15 wt %, Ca at 0.0001 to 0.005 wt %, Mg at 0.0001 to 0.005 wt %, and the balance including Fe and other impurities unavoidably added thereto.

A non-oriented electrical steel sheet with an average magnetostriction λ.sub.p-p at 400 Hz and 1.0 T of not more than 4.5×10.sup.−6, and area ratio of recrystallized grains at a section in rolling direction of steel sheet of 40 to 95% and an average grain size of 10 to 40 μm is obtained by subjecting a steel slab containing, in mass %, C: not more than 0.005%, Si: 2.8 to 6.5%, Mn: 0.05 to 2.0%, Al: not more than 3.0%, P: not more than 0.20%, S: not more than 0.005%, N: not more than 0.005%, Ti: not more than 0.003%, V: not more than 0.005% and Nb: not more than 0.005% and satisfying Si-2Al-Mn≥0 to hot rolling, hot-band annealing, cold rolling and finish annealing under adequate cold rolling and finish annealing conditions, and a motor core is manufactured by such a steel sheet.