Ultra-low carbon hot rolling weathering steel with yield strength larger than 550MPa

Abstract

The invention discloses an ultra low carbon hot rolling weathering steel with the yield strength of more than the grade of 550MPa and belongs to the manufacturing field of low alloy steel. The steel consists of the compositions with the following weight percentages: 0.01 to 0.05 percent of C, 0.10 to 0.40 percent of Si, 1.20 to 1.70 percent of Mn, equal to or less than 0.02 percent of P, equal to or less than 0.010 percent of S, 0.15 to 0.80 percent of Cu, 0.40 to 1.25 percent of Cr, 0.10 to 0.50 percent of Ni, equal to or less than 0.40 percent of Mo, 0.03 to 0.06 percent of Nb, equal to or less than 0.050 percent of Ti, 0.0010 to 0.0020 percent of Ca and the residual quantity of Fe and unavoidable impurities. The steel has good mechanical properties, the yield strength of equal to or more than 550MPa and the tensile strength of equal to or more than 650MPa which are both higher than that of traditional weathering steel. Besides, Ti is included in the compositions of the steel.

Description

technical field [0001] The invention belongs to the field of low-carbon and low-alloy steel manufacturing, in particular to an ultra-low-carbon hot-rolled weather-resistant steel with a yield strength greater than 550 MPa. Background technique [0002] Weathering steel is a low-carbon low-alloy steel, which is widely used in the manufacture of railway vehicles, transmission towers, offshore platforms and long-term outdoor engineering components. At the beginning of this century, the development of my country's railway vehicle manufacturing, transmission towers, offshore platforms, and long-term outdoor engineering components has put forward high-strength requirements for weathering steel. High-strength weathering steel with excellent atmospheric corrosion resistance is the main weathering steel in my country. development trend. [0003] The traditional weathering steel at home and abroad is mainly based on the Cu-P-Cr-Ni system, which contains high P and C, the C equivalent ...

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Problems solved by technology

[0003] The traditional weathering steel at home and abroad is mainly based on the Cu-P-Cr-Ni system, which contains high P and C, the C equivalent of the steel is high, and the welding performance is poor; at the same time, the high P content makes the steel cold brittleness resistance Poor, low-temperature toughness, easy to produce hot embrittlement, and the yield strength of traditional weathering steel is mainly 295MPa and 345MPa, and the strength level is low, which limits the use of weathering steel and cannot meet the market development demand of weathering steel

[0004] Chinese Patent No. 200510019116.0 introduces a low-temperature high-toughness atmospheric corrosion-resistant steel with good low-temperature impact toughness. Since the steel is based on Cu-Cr-Ni system, the C content is relatively high, ranging from 0.05 to 0.09 %, the alloy element Mn content reaches 2.10-3.0%, resulting in too high C equivalent, which is not conducive to the welding performance of the steel. The yield strength of the steel is 500MPa

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