The present invention relates to an additive manufacturing wire, containing, in terms of % by mass, 0%<Si≤2.0%, 0%<Mn≤6.0%, 3.0%≤Ni≤15.0%, 20.0%≤Cr≤30.0%, 1.0%≤Mo≤5.0%, 0%<N≤0.50%, with a balance being Fe and unavoidable impurities, in which C≤0.10% is satisfied, and 27<A<67 is satisfied, when Cr.sub.eq is defined as Cr+Mo+1.5Si+0.5(Nb+W)+2(Ti+Al), Ni.sub.eq is defined as Ni+30C+20N+0.5(Mn+Cu+Co), and A is defined as −16.2+6.3Cr.sub.eq−9.3Ni.sub.eq, here, in the definition of Cr.sub.eq and Ni.sub.eq, each element symbol indicates a content of the each element in units of % by mass.

An embodiment of the present invention provides a steel material, for a pressure vessel, comprising, in weight %, 0.06-0.25% of carbon (C), 0.05-0.50% of silicon (Si), 1.0-2.0% of manganese (Mn), 0.005-0.40% of aluminum (Al), 0.010% or less of phosphorus (P), 0.0010% 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), 0.05-0.15% of molybdenum (Mo), 0.01-0.50% of copper (Cu), 0.05-0.50% of nickel (Ni), 0.0005-0.0050% of magnesium (Mg), 0.0005-0.0050% of calcium (Ca), 0.0020% or less of oxygen (O), and the remainder being Fe and other unavoidable impurities. A microstructure comprises in terms of area fraction 30% or less of pearlite and the remainder being ferrite. A non-metallic inclusion contains Mg—Al—Ca—O composite oxide.

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.

An anti-collapse oil casing with high strength and a manufacturing method therefor, comprising the following chemical elements in percentage by mass: C:0.08%-0.18%; Si:0.1%-0.4%; Mn:0.1%-0.28%; Cr:0.2%-0.8%; Mo:0.2%-0.6%; Nb:0.02%-0.08% b; V:0.01%-0.15%; Ti:0.02%-0.05%; B:0.0015%-0.005%; and Al:0.01%-0.05%. The manufacturing method for the anti-collapse oil casing with high strength comprises the steps of: (1) smelting and continuous casting; (2) perforating, rolling, and sizing; (3) controlled cooling: the initial cooling temperature being Ar3+50° C. and the final cooling temperature being ≤80° C.; the cooling step being performed only to the outer surface of the casing without performing to the inner wall of the casing; and the rate of the controlled cooling being 30-70° C./s; (4) tempering; and (5) thermal straightening. The anti-collapse oil casing with high strength according to the present invention has reasonable chemical composition and process design, which not only has excellent economic efficiency, but also has high strength, high toughness and high anti-collapse performance.

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.

A cold rolled and heat treated steel sheet having a composition including the following elements, expressed in % by weight: 0.1%≤carbon≤0.6% 4%≤manganese≤20% 5%≤aluminum≤15% 0≤silicon≤2% aluminium+silicon+nickel≥6.5% and can possibly contain one or more of the following optional elements: 0.01%≤niobium≤0.3%, 0.01%≤titanium≤0.2% 0.01%≤vanadium≤0.6% 0.01%≤copper≤2.0% 0.01%≤nickel≤2.0% cerium≤0.1% boron≤0.01% magnesium≤0.05% zirconium≤0.05% molybdenum≤2.0% tantalum≤2.0% tungsten≤2.0% the remainder being composed of iron and unavoidable impurities caused by processing, wherein the microstructure of said steel sheet includes in area fraction, 10 to 50% of austenite, the austenite phase optionally including intragranular kappa carbides, the remainder being regular ferrite and ordered ferrite of D03 structure (Fe,Mn,X).sub.3Al, optionally including up to 2% of intragranular kappa carbides (Fe,Mn).sub.3AlC.sub.x said steel sheet presenting a ultimate tensile strength higher than or equal to 900 MPa. It also deals with a manufacturing method and with use of such grade for making vehicle parts.

A method is for manufacturing a high-strength steel sheet having a tensile strength of more than 1100 MPa and a yield strength of more than 700 MPa, a uniform elongation UE of at least 8.0% and a total elongation of at least 10%, made of a steel containing in percent by weight: 0.1%≤C≤0.25%, 4.5%≤Mn≤10%, 1%≤Si≤3%, 0.03%≤Al≤2.5%, the remainder being Fe and impurities resulting from the smelting, the composition being such that CMnIndex=C×(1+Mn/3.5)≤0.6. The method includes annealing a rolled sheet made of said steel by soaking it at an annealing temperature TA higher than the Ac.sub.1 transformation point of the steel but less than 1000° C., cooling the annealed sheet to a quenching temperature QT between 190° C. and 80° C. at a cooling speed sufficient to obtain a structure just after cooling containing martensite and retained austenite, maintaining the steel sheet at an overaging temperature PT between 350° C. and 500° C. for an overaging time Pt of more than 5 s cooling the sheet down to the ambient temperature.

A duplex ferritic austenitic stainless steel having high formability utilizing the TRIP effect and high corrosion resistance with the balanced pitting resistance equivalent is formed with less than 0.04 weight % carbon, 0.2-0.8 weight % silicon, less than 2.0 weight % manganese, 16.5-19.5 weight % chromium, 3.0-4.7 weight % nickel, 1.5-4.0 weight % molybdenum, less than 3.5 weight % tungsten, less than 1 weight % copper, 0.13-0.26 weight % nitrogen, the rest being iron and inevitable impurities occurring in stainless steels.

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%).