Micro Alloying Techniques for Reinforcement Steel Bars

Seismic steel bar with enhanced seismic performance through optimized composition and processing. The steel bar composition includes carbon, silicon, manganese, vanadium, magnesium, niobium, molybdenum, rare earth oxides, and iron. The steel bar achieves improved seismic performance by incorporating specific rare earth oxide concentrations and processing conditions. The composition and processing conditions enable the steel bar to maintain its yield strength while achieving the required yield strength-to-strength ratio and maximum elongation.

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Microalloyed high-strength, toughness, and low-density steel with improved mechanical properties compared to conventional austenitic steels. The steel combines the benefits of reduced density with enhanced strength and toughness through the addition of specific alloying elements, particularly V, Nb, Ti, and Mo, which precipitate as carbides in the austenitic microstructure. The alloying elements are precisely controlled to achieve optimal precipitation and refinement effects. The resulting steel exhibits superior mechanical properties, including high tensile strength, yield strength, and impact toughness, while maintaining a density reduction of approximately 10-20% compared to conventional austenitic steels.

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Ultra-high strength reinforcing bar for seismic-resistant structures that achieves exceptional seismic performance through controlled alloying. The bar combines a high carbon content (0.10-0.45 wt%), with specific alloy composition including manganese (0.40-1.80 wt%), chromium (0.10-1.0 wt%), vanadium (0.01-0.2 wt%), and copper (0.015-0.4 wt%), while maintaining optimal silicon (0.5-1.0 wt%) levels. The bar's composition enables precise control over microstructural evolution during processing, particularly through the formation of a bainite core that enhances seismic resistance.

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Rare earth microalloying in steel production through systematic control of RE addition. The method involves optimizing RE content and processing conditions to achieve controlled diffusion of carbon atoms in the steel microstructure. The control involves precise RE addition rates and cooling rates during the VIM and LF melting processes, with specific attention to the phase transformation kinetics and microstructural evolution. This approach enables the creation of high-performance steel alloys with tailored microstructural properties, particularly in applications requiring enhanced mechanical properties and corrosion resistance.

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Nitrogen-enriched vanadium-magnesium microalloyed ultrafine-grain corrosion-resistant HRB400E wire rod seismic reinforcement for seismic engineering applications. The reinforcement contains 0.0080-0.0100 wt% nitrogen, with the rest being iron and impurities. The microalloying process involves nitrogen enrichment through controlled nitrogen addition during alloying. The resulting ultrafine-grained microstructure exhibits enhanced corrosion resistance while maintaining high strength and ductility.

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High-strength reinforcing bar with enhanced fatigue resistance achieved through a novel alloy composition that balances strength and toughness. The composition comprises manganese (0.5-2.0 wt%), silicon (0.05-0.5 wt%), chromium (0.5-0.5 wt.), copper (0.5-4.5 wt.), boron (0.003-0.003 wt.), vanadium (0.25 wt.), nitrogen (0.012 wt%), phosphorus (0.03 wt.), and sulfur (0.03 wt.). This composition enables the formation of a microstructure that exhibits both high yield strength (750 MPa) and improved fatigue resistance (1.25-1.40 TS/YS ratio) through precipitation hardening and solid solution strengthening mechanisms. The microstructure features a ferrite-bainite-pearlite-precipitates structure with a bainite fraction of 90% and retained austenite fraction of 5%.

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Reinforcing bar for cryogenic applications exhibiting superior mechanical properties at room temperature while maintaining cryogenic toughness, ductility, and strength. The bar comprises a steel alloy containing chromium (Cr) more than 0.25% by weight, with nitrogen content between 0 and 0.01% by weight. The composition includes manganese (Mn), silicon (Si), phosphorus (P), sulfur (S), nitrogen (N), and copper (Cu) in addition to iron and other unavoidable impurities. The steel undergoes specific processing steps including reheating to 1000-1100°C, hot rolling to 920-1000°C, and a rapid cooling process. This combination enables the production of high-strength, cryogenic-resistant rebar with exceptional toughness and ductility, particularly at temperatures below -170°C.

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High-strength, seismic-resistant steel bar produced through a novel microalloying process for concrete structures. The steel bar combines niobium-titanium (Nb-Ti) microalloying with controlled rolling conditions to achieve exceptional seismic performance while maintaining weldability. The alloying process incorporates Ti to enhance solid N precipitation, grain refinement, and low-temperature toughness. This results in a high-strength, seismic-resistant steel bar with superior ductility and weldability compared to conventional 355MPa and 500MPa grades.

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Method for producing ultra-high-strength seismic steel bars with enhanced mechanical properties and reduced brittleness. The method involves preparing steel bars with specific microstructural features, including a non-pearlite structure with bainite content between 1-5%, and a pearlite structure with average ferrite-cementite distance of 50-100 nm.

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Micro-alloy steel composition for automotive parts that achieves high strength through controlled forging, featuring improved mechanical properties compared to conventional micro-alloy steels. The composition comprises carbon (0.15-0.2%), nitrogen (0.007%), silicon (0.25%), manganese (1.1%), chromium (0.6%), molybdenum (0.1%), nickel (0.1%), vanadium (0.15%), aluminum (0.05-0.15%), phosphorus (0.03%), and copper (0.25%) with a yield strength of 475-550 MPa and tensile strength of 680-720 MPa. The composition achieves these values through a novel microstructure that combines grain refinement effects from aluminum and vanadium with the strengthening mechanisms of nitride, carbide, and carbonitride phases.

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Niobium-ming microalloying for producing 32-40mm HRB400E fine-grained high-strength and tough seismic steel bars through a novel preparation method. The method involves niobium-ming microalloying to enhance grain refinement and microstructural control in HRB400E steel, resulting in high-strength and seismic performance.

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High-strength reinforcing bar with enhanced fatigue resistance achieved through a novel alloy composition. The bar comprises a steel alloy with specific carbon, manganese, silicon, chromium, copper, boron, vanadium, nitrogen, phosphorus, sulfur, nickel, niobium, and titanium content. The alloy composition enables precipitation and solid solution strengthening through controlled austenite grain refinement during hot rolling, resulting in a microstructure with ferrite, bainite, pearlite, retained austenite, and copper precipitates. The optimized composition balances strength, toughness, and ductility, enabling the production of high-strength reinforcing bars with improved fatigue resistance.

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Fine-grained high-strength seismic and corrosion-resistant steel bars for hydropower dams and other critical infrastructure through optimized production processes. The steel is produced through a controlled cooling process after hot rolling, where the steel is cooled to a precise temperature to prevent microstructural variations. This process enables the formation of high-strength, ductile, and corrosion-resistant microstructures while maintaining optimal mechanical properties. The steel is then refined in a LF furnace and further processed through continuous casting and rolling to produce the desired bar dimensions.

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Niobium-vanadium composite microalloyed high-strength seismic HRB500E steel bar with improved weldability and corrosion resistance. The steel composition is optimized to achieve enhanced microalloyed properties while maintaining sufficient strength and weldability. The composition includes niobium and vanadium in specific mass fractions, along with controlled amounts of other elements, and a balanced composition of base metals. The steel is produced through a billet preparation process followed by controlled rolling to achieve the desired microstructure and properties.

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High-strength and high-toughness steel wire strand with improved mechanical properties through controlled microstructure engineering. The strand comprises multiple steel wires twisted together to form a continuous strand, with a specialized stranding process that introduces controlled microstructural features. The strand is then stabilized through continuous prestressing, achieving superior mechanical performance compared to conventional prestressed strands.

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High-strength, weldable steel bar with improved manufacturing process for achieving both enhanced mechanical properties and enhanced weldability. The manufacturing process involves controlled rolling and microalloying of high-carbon steel to achieve both high strength and improved weldability. The microalloying process incorporates beneficial elements such as Cr, Mo, V, Ni, and Cu to enhance mechanical properties while maintaining weldability. The manufacturing process combines controlled rolling and microalloying to produce high-strength steel bars with improved weldability, meeting the requirements of the new national standard GB/T 1499.2-2018.

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Manufacturing method for high-strength niobium-containing steel bars that enhances precipitation strengthening through controlled rolling and cooling. The method involves controlling rolling temperatures during hot rolling to refine grain structure while maintaining niobium in a solid solution state. This approach enables the precipitation strengthening effect of niobium to be maximized without compromising the steel's microstructure. The method specifically addresses the limitations of traditional high-temperature rolling and solid solution refining techniques that can lead to continuous yield of steel bars.

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A high-strength, high-seismic reinforcing bar for concrete structures that combines enhanced mechanical properties with improved toughness. The bar contains 0.10-0.40% carbon, 0.05-0.50% silicon, 0.50-2.0% manganese, and phosphorus (P) in a controlled composition. The bar's surface layer is tempered to a martensitic structure, while the central portion exhibits a composite ferrite-pearlite microstructure with a tissue fraction of 35% or higher. This dual-phase structure provides both high strength and improved toughness, particularly at elevated temperatures. The composition and microstructure are optimized to balance strength, ductility, and seismic performance.

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Nitrogen-rich niobium microalloyed 400MPa ultra-fine grain seismic steel bar for reinforced concrete structures, prepared through a novel process involving controlled nitrogen addition during steel production. The bar achieves superior mechanical properties through precise control of nitrogen content and alloying elements, resulting in a microalloyed steel with enhanced toughness and overall performance.

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Thermostrength construction steel with improved seismic performance through optimized microalloying. The steel contains controlled amounts of niobium (Nb) and titanium (Ti) within a specific ratio, combined with precise control over alloying elements like aluminum (Al), to achieve high-temperature properties. The steel formulation enables enhanced strength and seismic performance while maintaining cost competitiveness.

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