Provided are a duplex stainless steel sheet having high surface quality and high corrosion resistance manufactured through a twin roll strip casting process, and a method for manufacturing the duplex stainless steel sheet.

A steel product having, by weight, less than 0.25% carbon, between 0.20 and 2.0% manganese, between 0.05 and 0.50% silicon, aluminum 0.008% or less by weight, and at least one element selected from the group consisting of titanium between about 0.01% and about 0.20%, niobium between about 0.01% and about 0.20%, molybdenum between about 0.05% and about 0.50%, and vanadium between about 0.01% and about 0.20%, and having a microstructure comprised of a majority bainite, and fine oxide particles of silicon and iron distributed through the steel microstructure of average precipitate size less than 50 nanometers. The yield strength of the steel product may be at least 55 ksi (380 MPa) or the tensile strength of at least 500 MPa, or both. The steel product may have total elongation of at least 6% or 10%, and thickness less than 3.0 mm.

A method for manufacturing thin strip continuously cast 700 Mpa grade high strength weather-resistant steel, the method comprising the following steps: 1) casting a 1-5 mm thick cast strip in a double roller continuous casting machine, the cast strip comprising the following chemical compositions by weight percent: C 0.03-0.1%, Si0.4%, Mn 0.75-2.0%, P 0.07-0.22%, S0.01%, N0.012%, and Cu 0.25-0.8%, further comprising more than one of Nb, V, Ti and Mo: Nb 0.01-0.1%, V 0.01-0.1%, Ti 0.01-0.1%, and Mo 0.1-0.5%, and the balance being Fe and unavoidable impurities; 2) cooling the cast strip at a rate greater than 20 C./s; 3) hot rolling the cast strip under a temperature of 1050-1250 C. at a reduction rate of 20-50% and a deformation rate greater than 20 s1; then conducting austenite online recrystallization, the thickness of the hot rolled strip being 0.5-3.0 mm; 4) cooling at a rate of 10-80 C./s; and 5) rolling up under a temperature of 500-650 C. The obtained steel strip microstructure mainly consists of uniformly distributed bainites and needle-shaped ferrites.

There is provided a method of manufacturing a high nitrogen duplex stainless steel sheet through a twin roll strip casting process without the occurrence of surface swelling on the high nitrogen duplex stainless steel sheet.

A containment system for laterally containing a liquid metal material or liquid metal alloy at an open side end of a passage defined between two casting members, the system including a pneumatic device ending with a hollow end element adapted to be arranged close to the open side end of the passage, wherein the hollow end element defines a chamber therein, wherein the pneumatic device is adapted to feed a compressed aeriform substance into the chamber, and wherein the hollow end element is provided with at least one blowing face for blowing the compressed aeriform substance from the chamber towards a side containment zone for the liquid metal.

A method for producing ultra-thin hot-rolled strip steel, the method comprising the following process steps: A. a smelting process: feeding scrap steel into an induction electric furnace (1) for smelting so that the scrap steel melts into molten steel; B. a refining process: using a ladle refining furnace (2) and a ladle vacuum degassing furnace (3) to refine the molten steel; C. a continuous casting process: casting the refined molten steel into a cast strip blank that has a thickness of 1.6-2.5 mm by means of a dual-roller thin strip continuous casting system (4); D. a hot rolling process: directly feeding the cast strip blank that was cast in the continuous casting process to a single-stand hot rolling mill (9) for rolling to produce hot-rolled strip steel, the thickness of the hot-rolled strip steel being 0.8-1.5 mm; E. a cooling coiling process: performing atomizing cooling on the hot-rolled strip steel, and coiling after the strip steel temperature is controlled to be 400-750 C. The present method achieves an extremely compact, environmentally-friendly and economical ultra-thin hot-rolled strip steel production process flow, and achieves the environmentally-friendly and economical continuous production of metal plates and strips.

A thin metal strip continuous casting method using momentum flow distribution, comprising the steps of: adjusting the position of a flow distribution device (2), and starting a double-roller thin strip continuous casting apparatus; molten metal (3) forming a uniform sheet-shaped molten metal flow (4) having an initial momentum after the molten metal (3) passes through the flow distribution device; the sheet-shaped molten metal flow entering a molten pool (5) at a superheat degree of 50-100 C. and an initial velocity of 0.5-2 m/s, wherein the flow distribution device is spaced apart from the molten pool; under the action of the initial velocity of the molten metal and in the molten pool, forming a whirlpool, which is adjacent to surfaces of two cooling rollers and has a momentum stirring action; and completing the solidification of the molten metal under the momentum stirring action of the whirlpool along with the rotation of the two cooling rollers. In the method, a whirlpool, which is adjacent to surfaces of cooling rollers and has a momentum stirring action, is formed in a molten pool by means of the kinetic energy of molten metal, such that equiaxed crystals can be prepared when a superheat degree is as high as 50-100 C., and the proportion of equiaxed crystals can be increased to 100%, thereby refining crystal grains and alleviating segregation.

In one embodiment, a lead strip caster for battery grids includes a ladle, a nozzle, and a pair of rollers. The lead strip caster produces a continuous lead strip for use as battery positive plate grids. The ladle has an inlet to receive molten lead and has an outlet. The nozzle has at least one passage that communicates with the outlet of the ladle in order to receive molten lead from the ladle. The first roller is situated at a first exterior side of the nozzle. The first roller rotates via a first driver. The second roller is situated at a second exterior side of the nozzle. The second roller rotates via a second driver.

A method for continuous thin strip casting comprises: introducing molten steel through a long nozzle into a tundish from a ladle, the tundish is one strand tundish, and the molten steel flows below a weir, then passes a first dam and enters a channel with an induction heating device, and the heated molten steel then flows out from an outlet at the other side of the tundish to a nozzle also with an induction heating device for casting. The distances between the weirs of the tundish and the channel have optimal distance ranges. The present invention can improve the casting stability and the quality of the casting strip.

There is provided a method for manufacturing a duplex stainless steel sheet having reduced inclusions through argon oxygen decarburization (AOD), ladle treatment (LT), and twin roll strip casting. The method includes deoxidizing molten steel using silicon (Si) during the AOD, wherein the molten steel has a silicon (Si) content of 0.55 wt % to 0.75 wt % at the end of the AOD.