Provided are lean duplex stainless steel having a dual-phase structure of an austenite phase and a ferrite phase, and a method for producing the lean duplex stainless steel. The lean duplex stainless steel, as a ferrite-austenite stainless steel, has the preferred stacking fault energy (SFE) value of the austenite phase, expressed by the formula 2 below, of 19-37 and critical strain value range, within which the strain-induced martensite phases occurs, of 0.1−0.25. Formula 2: SFE=25.7+1.59×Ni/[K(Ni)−K(Ni)×V(γ)+V(γ)]+0.795×Cu/[K(Cu)−K(Cu)×V(γ)+V(γ)]−0.85×Cr/[K(Cr)−K(Cr)×V(γ)+V(γ)]+0.001×(Cr/[K(Cr)−K(Cr)×V(γ)+V(γ)]).sup.2+38.2×(N/[K(N)−K(N)×V(γ)+V(γ)]).sup.0.5−2.8×Si/[K(Si)−K(Si)×V(γ)+V(γ)]−1.34×Mn/[K(Mn)−K(Mn)×V(γ)+V(γ)]+0.06×(Mn/[K(Mn)−K(Mn)×V(γ)+V(γ)]).sup.2. Ni, Cu, Cr, N, Si and Mn indicate the overall content (wt. %) of the respective constituent element, and K(x) is the distribution index of respective constituent element (x) and is expressed by the formula 3 below, and V(γ) is the component ratio of austenite (in the 0.45-0.75 range). Formula 3: K(x)=[amount of element x in ferrite phase]/[amount of element x in austenite phase]

To achieve a substantially uniform microstructure across a continuously cast thin metal strip, it is beneficial to cool a width of the strip to a substantially constant temperature before further cooling the strip to reach any desired phase transformation temperature. Accordingly, methods of continuously casting a thin metal strip may include moving the thin strip to a cooling section, the cooling section having a plurality of coolant discharge ports configured to discharge a flow of coolant along the thin strip; initially sensing the temperature of the thin strip to determine a temperature distribution across the width of the thin strip, and producing a sensor signal corresponding to a sensed temperature at each of the first plurality of locations; and individually controlling the cooling across a width of the thin strip by way of the plurality coolant discharge ports in each zone of a first row using the determined temperature distribution.

Disclosed is a continuous rapid solidification apparatus, which comprises a cooling roll configured to cool a molten metal supplied to an outer circumference surface thereof; a crucible configured to supply the cooling roll with the molten metal; a molten metal supply configured to melt a raw material metal and supply the crucible with the molten metal; a first chamber configured to form a sealed space where the molten metal supplied from the crucible is cooled by the cooling roll; and a second chamber configured to be formed of a space separated from the first chamber and to form a sealed space where the molten metal is supplied to the crucible by the molten metal supply.

Disclosed is a continuous rapid solidification apparatus, which comprises a cooling roll configured to cool a molten metal supplied to an outer circumference surface thereof; a crucible configured to supply the cooling roll with the molten metal; a molten metal supply configured to melt a raw material metal and supply the crucible with the molten metal; a first chamber configured to form a sealed space where the molten metal supplied from the crucible is cooled by the cooling roll; and a second chamber configured to be formed of a space separated from the first chamber and to form a sealed space where the molten metal is supplied to the crucible by the molten metal supply.

A method of casting a metal ingot with a microstructure that facilitates further working, such as hot and cold rolling. The metal is cast in a direct chill casting mold, or the equivalent, that directs a spray of coolant liquid onto the outer surface of the ingot to achieve rapid cooling. The coolant is removed from the surface at a location where the emerging embryonic ingot is still not completely solid, such that the latent heat of solidification and the sensible heat of the molten core raises the temperature of the adjacent solid shell to a convergence temperature that is above a transition temperature for in-situ homogenization of the metal. A further conventional homogenization step is then not required. The invention also relates to the heat-treatment of such ingots prior to hot working.

A method of casting a metal ingot with a microstructure that facilitates further working, such as hot and cold rolling. The metal is cast in a direct chill casting mold, or the equivalent, that directs a spray of coolant liquid onto the outer surface of the ingot to achieve rapid cooling. The coolant is removed from the surface at a location where the emerging embryonic ingot is still not completely solid, such that the latent heat of solidification and the sensible heat of the molten core raises the temperature of the adjacent solid shell to a convergence temperature that is above a transition temperature for in-situ homogenization of the metal. A further conventional homogenization step is then not required. The invention also relates to the heat-treatment of such ingots prior to hot working.

A side dam for a continuous metal casting apparatus includes an insulator and a belt system having an endless belt. The endless belt includes a belt surface, and the endless belt is movable relative to the insulator such that a portion of the belt surface is configured to face a casting cavity of the continuous metal casting apparatus as the endless belt is moved. In some examples, the endless belt is movable in a plane of motion that is perpendicular to the belt surface.

The present disclosure shows a superplastic-forming aluminum alloy plate that has excellent properties for superplastic-forming, such as blow forming, and that has excellent surface properties after forming. Shown is a superplastic-forming aluminum alloy plate and a production method therefor, the superplastic-forming aluminum alloy plate being characterized by comprising an aluminum alloy which contains 2.0 to 6.0 mass % Mg, 0.5 to 1.8 mass % Mn and 0.40 mass % or less Cr and in which the balance consists of Al and unavoidable impurities, wherein the unavoidable impurities are restricted to have 0.20 mass % or less Fe and 0.20 mass % or less Si, the 0.2% proof stress is 340 MPa or more, and the density of intermetallic compounds having an equivalent circular diameter of 5 to 15 μm at the RD-TD plane which extends along the center of the plate cross-section is 50 to 400 pieces/mm.sup.2.

Methods of forming a high-strength metal alloy precursor by tailor-casting strips having a tailored thickness across a width of a strip material are provided. The tailor-cast strips have varying thickness throughout the width, which can then be further tailor rolled to a final required thickness profile/tailored thickness. Such tailor-casting method can be conducted by contacting a patterned surface of a casting roller or a casting block with a liquid high-strength metal alloy in a continuous casting process. The present disclosure provides methods of continuously casting a strip having varying thickness across the width allows for improved product in subsequent processing, like tailor rolling. Methods of making a high-strength metal alloy structural automotive component from a tailor-cast blank having a tailored thickness are also provided.

Methods of forming a high-strength metal alloy precursor by tailor-casting strips having a tailored thickness across a width of a strip material are provided. The tailor-cast strips have varying thickness throughout the width, which can then be further tailor rolled to a final required thickness profile/tailored thickness. Such tailor-casting method can be conducted by contacting a patterned surface of a casting roller or a casting block with a liquid high-strength metal alloy in a continuous casting process. The present disclosure provides methods of continuously casting a strip having varying thickness across the width allows for improved product in subsequent processing, like tailor rolling. Methods of making a high-strength metal alloy structural automotive component from a tailor-cast blank having a tailored thickness are also provided.