High-performance weather-proof building structural steel and manufacturing method thereof

Abstract

The invention relates to high-performance weather-proof building structural steel and a manufacturing method thereof. The composition system of low C-medium Mn-low N-micro Nb alloying-ultramicro Ti processing low content alloy weather-proof steel is taken as foundation, the acid solution Als content in the steel is increased properly, and the range of the acid solution Als content is controlled; the zero dimension Ni equivalent weight is controlled to be more than or equal to 0.35, the Ceq is less than or equal to 0.425%, and the Mn / C is more than or equal to 10; the weather-proof property index DNH is more than or equal to 6.0%; and the Ca is processed, the Ca / S is controlled within the range of 1.0-3.0, and Ca*S 0.28 is less than or equal to 1.0*10<-3>. By adopting a TMCP technique, a weather-proof steel plate with good toughness, strong plasticity matching, low yield ratio, atmosphere corrosion resistance, excellent weldability and anti-fatigue performance can be obtained, is especially suitable for non-coating high-rise building structure and bridge structure, and can realize stable batch industrialized production with low cost.

Description

technical field [0001] The invention relates to a high-performance weather-resistant building structure steel and a manufacturing method thereof, which are mainly used for high-rise building structures and non-painted large-scale bridge structure manufacturing materials. Background technique [0002] As we all know, low-carbon (high-strength) low-alloy steel is one of the most important engineering structural materials, widely used in oil and gas pipelines, offshore platforms, shipbuilding, bridge structures, boiler pressure vessels, building structures, automobile industry, railway transportation and machinery under manufacture. The properties of low-carbon (high-strength) low-alloy steel depend on its chemical composition and the process system of the manufacturing process, among which strength, toughness and weldability are the most important properties of low-carbon (high-strength) low-alloy steel, which are ultimately determined by the finished steel state of the micro...

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Problems solved by technology

[0005] When manufacturing thick steel plates for atmospheric corrosion resistant welded structures, it is generally necessary to add a certain amount of weather-resistant alloying elements such as P, Ni, Cu, and Cr to the steel to form a dense amorphous protective film on the surface of the steel plate. Prevent air from entering the interior of the steel plate to achieve atmospheric corrosion resistance (see "Xishan Memorial Technical Lectures" 159-160, P84-P85); resulting in poor toughness and weldability of the base metal steel plate, especially the fusion line of the welded joint. The impact toughness of the heat-affected zone is very poor

For this reason, Japan adopts a low C content composition design, adds microalloying elements Ti and Nb, and combines the controlled rolling process to greatly improve the weldability and low temperature toughness of the steel plate ("Iron Manufacturing Research", 1982, Vol.309, P98; "R&D Kobe Steel Technical Report", 1988, Vol.38, P97); in order to develop weather-resistant steel used in cold regions, Japan adopts low C-high Al-low N-micro-Ti treatment composition design technology, combined with controlled rolling process Successfully produced weather-resistant steel plates that meet the low temperature toughness of -40°C ("Iron and Steel", 1985, Vol.71, S593), but the strength level of these steel plates is 490MPa, and the thickness generally does not exceed 50mm; Reduce the strength of the steel plate with ferrite / pearlite microstructure and reduce the yield strength more than the tensile strength ("Xishan Memorial Technical Lecture" 86-87, P11), so it is produced by controlled rolling or normalizing process Yield strength ≥ 420MPa, tensile strength ≥ 550MPa, yield strength ratio ≤ 0.80, Charpy transverse impact energy (single value) ≥ 47J at -40°C, large heat input can weld thick steel plates (thickness ≥ 40mm) for weather-resistant structures, The carbon equivalent Ceq[C+Mn / 6+(Cr+Mo+V) / 5+(Cu+Ni) / 15] of the steel plate generally needs to be controlled above 0.46%, which will seriously deteriorate the low-temperature toughness and weldability of the base metal of the steel plate ;

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