Disclosed is a follow-up process-omitting type high-strength hot-rolled steel sheet having an excellent yield ratio and a method for manufacturing the same. The hot-rolled steel sheet includes, in percent by weight (wt %), 0.12% or more and less than 0.3% of C, 0.5% or less of Si (excluding 0), 0.1 to 2.5% of Mn, 0.0005 to 0.005% of B, 0.02% or less of P, 0.01% or less of S, and the balance of Fe and inevitable impurities, has a microstructure including at least 95 vol % of martensite, has a yield ratio (yield strength/tensile strength) of 0.75 or more, is manufactured by continuous hot rolling, and is manufactured without performing a follow-up process such as cold rolling and heat treatment.

Provided are a non-heat treated wire rod having high drawability and impact toughness, and a method for manufacturing the non-heat treated wire rod. The non-heat treated wire rod includes, by wt%, C: 0.02% to 0.30%, Si: 0.05% to 0.8%, Mn: 0.5% to 2.0%, Cr: 1.0% or less, P: 0.03% or less, S: 0.03% or less, sol.Al: 0.01% to 0.07%, N: from greater than 0.01% to 0.02%, Nb: 0.1% or less, V: 0.5% or less, and Ti: 0.1% or less, and a balance of Fe and inevitable impurities, wherein the non-heat treated wire rod has a microstructure including ferrite and pearlite.

A cold rolled and annealed steel sheet includes by weight: 0.6≤C≤1.3%, 15.0≤Mn≤35%, 5≤Al≤15%, Si≤2.40%, S≤0.03%, P≤0.1%, N≤0.1%, possibly one or more optional elements chosen among Ni, Cr and Cu in an respective amount of up to 4.0%, up to 3.0% and up to 3.0% and possibly one or more elements chosen among B, Ta, Zr, Nb, V, Ti, Mo, and W in a cumulated amount of up to 2.0%, the remainder of the composition making up of iron and inevitable impurities resulting from the elaboration, the microstructure of the sheet including optionally up to 3% of kappa carbides, optionally up to 10.0% of granular ferrite, the remainder being made of austenite, the average grain size and average aspect ratio of the austenite being respectively below 6 μm and comprised between 1.5 and 6 and the average grain size and average aspect ratio of the ferrite, when present, being respectively below 5 μm and below 3.0.

This application provides Fe—Mn—Al—C lightweight steel, including: Fe, wherein a weight percentage of the Fe is greater than or equal to 50.4 wt %; Mn, wherein a weight percentage of the Mn is 25-35 wt %; Al, wherein a weight percentage of the Al is 6-12 wt %; C, wherein a weight percentage of the C is 0.8-2.0 wt %; and O, wherein a weight percentage of the O is 0.005-0.6 wt %. This application further provides a terminal to which the Fe—Mn—Al—C lightweight steel is applied, a production method for the Fe—Mn—Al—C lightweight steel, a steel mechanical part, and an electronic device. The lightweight steel in this application has low density, high strength, and high elongation.

Provided is a steel component with excellent surface fatigue strength. The steel component has a nitride compound layer with a thickness of 5.0 μm to 30.0 μm and a hardened layer in an order from a component surface to a component inside, where a thickness of a porous layer on an outermost surface of the nitride compound layer is 3.0 μm or less and 40.0% or less of a thickness of the nitride compound layer, and the hardened layer has a hardness of HV600 or more at a position of 50 μm inward from the component surface, a hardness of HV400 or more at a position from the component surface to the component inside of 400 μm, and a hardness of HV250 or more at a position from the component surface to the component inside of 600 μm.

A high permeability grain oriented electrical steel having a chemistry comprising, all in weight percent, 2.5% to 4.5% silicon, 0.02% to 0.08% carbon, 0.01 to 0.05% aluminum, 0.005% to 0.050% sulfur or selenium, 0.02 to 0.20% manganese, 0.05 to 0.20% tin, 0.05 to 1% copper, 0.5% to 2.0% chromium, up to 0.10% phosphorus and up to 0.20% antimony with the balance being essentially iron and residual elements. The steel contains chromium and phosphorus in such amounts that a Cr:(P+0.25Sb) ratio is below 80:1 or, below 50:1, or below 30:1 which provides highly stable magnetic properties in the finished steel sheet. A hot processed band comprised of such steel is annealed and rapidly cooled after such annealing at a rate of at least 50° C. per second from 875-950° C. to a temperature below 400° C. prior to cold rolling to final thickness. Such steel forming a hot processed band having a thickness of from 1.5 to 4.0 mm and having a volume resistivity of at least 50 μΩ-cm, an austenite volume fraction (γ1150° C.) of at least 20%, and an isomorphic layer thickness of at least 2% of the total thickness on at least one surface of the hot processed band.

Provided is an alloy steel manufacturing method, the method including: preparing a manganese-containing first molten ferroalloy; preparing a chromium-containing second molten alloy; preparing molten steel; mixing the first molten ferroalloy and the second molten ferroalloy to manufacture third molten ferroalloy; and mix pouring the third molten ferroalloy and the molten steel to manufacture an alloy steel, wherein the phosphorous concentration in the molten steel may efficiently be controlled by reducing the converter end point temperature of the molten steel to improve a phosphorous control capacity during converter refining.

The present invention describes a method of dynamical adjustment for manufacturing a thermally treated steel sheet. The method includes: A. a control step, wherein at least one sensor detects a deviation happening during the thermal treatment, B. a calculation step performed when the deviation is detected during the thermal treatment such that a new thermal path TP.sub.target is determined to reach m.sub.target taking the deviation into account, such calculation step including: 1) a calculation substep, wherein at least two thermal path, TP.sub.x corresponding to one microstructure m.sub.x obtained at the end of TP.sub.x, are calculated based on TT and the microstructure m.sub.i of the steel sheet to reach m.sub.target, 2) a selection substep wherein one new thermal path TP.sub.target to reach m.sub.target is selected, TP.sub.target being chosen from said TP.sub.x and being selected such that m.sub.x is the closest to m.sub.target, C. a new thermal treatment step, wherein TP.sub.target is performed online on the steel sheet.

The present invention describes a method of dynamical adjustment for manufacturing a thermally treated steel sheet. The method includes: A. a control step, wherein at least one sensor detects a deviation happening during the thermal treatment, B. a calculation step performed when the deviation is detected during the thermal treatment such that a new thermal path TP.sub.target is determined to reach m.sub.target taking the deviation into account, such calculation step including: 1) a calculation substep, wherein at least two thermal path, TP.sub.x corresponding to one microstructure m.sub.x obtained at the end of TP.sub.x, are calculated based on TT and the microstructure m.sub.i of the steel sheet to reach m.sub.target, 2) a selection substep wherein one new thermal path TP.sub.target to reach m.sub.target is selected, TP.sub.target being chosen from said TP.sub.x and being selected such that m.sub.x is the closest to m.sub.target, C. a new thermal treatment step, wherein TP.sub.target is performed online on the steel sheet.

Disclosed are a pressure vessel steel sheet and a method for manufacturing the same, the steel sheet comprising: by wt %, 0.10-0.20% of C, 0.15-0.40% of Si, 1.15-1.50% of Mn, 0.45-0.60% of Mo, 0.03-0.30% of Cu, 0.025% or less of P, 0.025% or less of S and 0.005-0.06% of sol. Al; two or more selected from the group consisting of 0.03-0.30% of Cr, 0.002-0.025% of Nb and 0.002-0.025% of Zr, and the balance of Fe and inevitable impurities, wherein the structure comprises a mixture structure of ferrite, perlite and tempered bainite after post weld heat treatment (PWHT) for 60 hours at 600-660° C., and the area fraction of the tempered bainite is at least 10% (excluding 100%).