A cold rolled and annealed steel sheet includes by weight: 0.6<C<1.3%,15.0<Mn<35%, 6.0<Al<15%, Si<2.40%, S<0.015%, P<0.1%, N<0.1%, iron and inevitable impurities, optionally one or more of Ni, Cr and Cu in an individual amount of up to 3% and optionally one or more of B, Ta, Zr, Nb, V, Ti, Mo, and W in a cumulated amount of up to 2.0%, a microstructure of the sheet comprising at least 0.1% of intragranular kappa carbides, at least 80% of the kappa carbides have an average size below 30 nm, the remainder being made of austenite, an average grain size of the austenite being below 6 μm, an average aspect ratio of the austenite being between 1.5 and 6, an average grain size of the ferrite, when present being below 5 μm, and an average aspect ratio of the ferrite, when present, being below 3.0.

A method of forming a shaped steel object, includes cutting a blank from an alloy composition. The alloy composition includes 0.1-1 wt. % carbon, 0.1-3 wt. % manganese, 0.1-3 wt. % silicon, 1-10 wt. % aluminum, and a balance being iron. The method also includes heating the blank to a temperature above a temperature at which austenite begins to form to generate a heated blank, transferring the heated blank to a die, forming the heated blank into a predetermined shape defined by the die to generate a shaped steel object, and decreasing the temperature of the shaped steel object to ambient temperature. The heating is performed under an atmosphere comprising at least one of an inert gas, a carbon (C)-based gas, and nitrogen (N.sub.2) gas.

A method of forming a shaped steel object is provided. The method includes cutting a blank from an alloy composition including 0.05-0.5 wt. % carbon, 4-12 wt. % manganese, 1-8 wt. % aluminum, 0-0.4 wt. % vanadium, and a remainder balance of iron. The method also includes heating the blank until the blank is austenitized to form a heated blank, transferring the heated blank to a press, forming the heating blank into a predetermined shape to form a stamped object, and decreasing the temperature of the stamped object to a temperature between a martensite start (Ms) temperature of the alloy composition and a martensite final (Mf) temperature of the alloy composition to form a shaped steel object comprising martensite and retained austenite.

The invention relates to a method for producing a steel material, particularly a corrosion-resistant steel material for pumps and similar, in which a steel corresponding to the following analysis (in wt. %) is smelted: C<0.050; Si<0.70; Mn<1.00; P<0.030; S<0.010; Cr=14-15.50; Mo=0.30-0.60; Ni=4.50-5.50; V<0.20; W<0.20; Cu=2.50-4.00; Co<0.30; Ti<0.05; Al<0.05; Nb<0.05; Ta<0.05; N<0.05.

What is provided is a high-strength steel sheet having a large bake hardening amount and a uniform bake hardenability is provided according to the present invention, the high-strength steel sheet comprising, by mass %: C: 0.13% to 0.40%; Si: 0.500% to 3.000%; Mn: 2.50% to 5.00%; P: 0.100% or less; S: 0.010% or less; Al: 0.001% to 2.000%; N: 0.010% or less; and a remainder consisting of Fe and impurities, wherein martensite is 95% or more in an area ratio, and residual structure is 5% or less in an area ratio, a ratio C1/C2 of an upper limit C1 (mass %) of Si concentrations to a lower limit C2 (mass %) of the Si concentrations in a cross section in a thickness direction is 1.25 or less, precipitates having a major axis of 0.05 μm or more and 1.00 μm or less and an aspect ratio of 1:3 or more are included in a number density of 30/μm.sup.2 or more, and a tensile strength is 1300 MPa or more.

An iron-based alloy composition including: boron (B): 1.6-2.4 wt. %; carbon (C): 2.2-3.0 wt. %; chromium (Cr): 3.5-5.0 wt. %; manganese (Mn): below 0.8 wt. %; molybdenum (Mo): 16.0-19.5 wt. %; nickel (Ni): 1.0-2.0 wt. %; silicon (Si): 0.2-2.0 wt. %; vanadium (V): 10.8-13.2 wt. %; and balanced with iron (Fe). Further, an item including a substrate portion and a hardfacing coating bonded to the substrate portion, wherein the hardfacing coating is made by an overlay welding process using the iron-based alloy composition.

A shock absorbing member which can increase impact absorption energy and also enables thinning of a steel sheet that is a starting material, a method for producing the shock absorbing member, and a method for producing a steel sheet for cold plastic working are provided. The shock absorbing member includes a ridge portion formed in a curved shape as viewed from a longitudinal direction, and a wall portion extending from the ridge portion. In the wall portion, a ratio σ.sub.5/τ.sub.5 between a tensile stress σ.sub.5 when an elongation in a tensile test is 5% and a shear stress τ.sub.5 when a shear strain in a shear test is 5√3% is 1.70 or less, or a ratio σ.sub.10/τ.sub.10 between a tensile stress σ.sub.10 when an elongation in a tensile test is 10% and a shear stress τ.sub.10 when a shear strain in a shear test is 10√3% is 1.70 or less.

Provided is a high-strength steel sheet including: 0.12% to less than 0.17% of carbon (C), 0.3% to 0.8% of silicon (Si), 2.5% to 3.0% of manganese (Mn), 0.4% to 1.1% of chromium (Cr), 0.01% to 0.3% of aluminum (Al), 0.01% to 0.03% of niobium (Nb), 0.01% to 0.03% of titanium (Ti), 0.001% to 0.003% of boron (B), 0.04% or less of phosphorus (P), 0.01% or less of sulfur (S): 0.01% or less of nitrogen (N), and a balance of iron (Fe) and inevitable impurities. The contents of C, Si, and Al satisfy: [C]+[Si]+[Al])/5≤0.35 wt. A microstructure includes more than 1% to 4% or less of retained austenite, more than 10% to 20% or less of fresh martensite, 5% or less (excluding 0%) of ferrite, more than 50% to 70% or less of tempered martensite, and a balance of bainite.

The present invention provides a high-strength steel sheet, which can be used in various applications including automobile parts and exhibits excellent collision safety and excellent moldability, and a method for manufacturing the high-strength steel sheet. The high-strength steel sheet according to an aspect of the present invention satisfies a predetermined chemical composition and has a metallographic microstructure having ferrite fraction: 0% to 10%, MA fraction: 0% to 30%, hard phase other than ferrite and MA: 70% to 100% in terms of area proportion and retained austenite fraction: 5% to 30% in terms of volume proportion, and in the high-strength steel sheet, the skewness of IQ as analyzed by the EBRD method is −1.2 to −0.3 when the skewness is expressed by a predetermined relational expression in a case where crystal grains having a bcc structure and a bct structure are regarded as an aggregation of regions having an area of 0.05 μm.sup.2.

A stainless steel seamless pipe having high strength and excellent corrosion resistance, and a method for producing the same. The stainless steel seamless pipe has a specified composition and satisfies a predetermined formula. The stainless steel seamless pipe has a microstructure containing at least 30% martensitic phase, at most 60% ferrite phase, and at most 40% retained austenite phase by volume, the stainless steel seamless pipe having a yield strength of 758 MPa or more.