A kind of high toughness, high weather resistance steel and its manufacturing method

Abstract

The invention discloses high-toughness and high-weather-resistance steel and a manufacturing method thereof. The high-toughness and high-weather-resistance steel comprises the following components in percentage by weight: 0.035-0.075% of C, no more than 0.30% of Si, 0.40-0.80% of Mn, 0.07-0.11% of P, no more than 0.004% of S, 0.20-0.50% of Cu, 0.10-0.40% of Ni, 0.40-0.70% of Cr, 0.008-0.016% of Ti, 0.010-0.030% of Nb, no more than 0.0050% of N, 0.001%-0. 004% of Ca, and the balance of Fe and unavoidable impurities, wherein by taking a C-Mn-P component system with low C, low Mn and high P as a foundation and through the alloying of Cu, Ni and Cr, [%C] / [%P] is controlled to be not smaller than 0.49, [%Mn] / [%C] is controlled to be not smaller than 10, the weather resistance index DNH is controlled to be not smaller than 6.50%, [%C]*([%P]+2.5[%S]) is controlled to be not more than 0.0025, [%Ca] / [%S] is controlled to be equal to 1.0-3.0, ([%Cu]+0.36[%Ni]+0.27[%Cr])*[%P] is controlled to be not smaller than 0.030, [%Ca]*[%S]0.28 is controlled to be not more than 0.002, and a TMCP (ThermoMechanical Control Process) is adopted. Therefore, the high-toughness and high-weather-resistance steel has excellent low-temperature toughness, bending cold machining characteristic and high weather resistance, and is suitable to be used as a compartment body structure of a coating-free high-speed train.

Description

technical field [0001] The invention relates to a high-toughness, high-weather-resistance steel and its manufacturing method, its yield strength ≥ 355MPa, tensile strength ≥ 490MPa, Charpy transverse impact energy (single value) at -40°C ≥ 47J, relative corrosion rate of ordinary structural steel ≤ 20%, mainly used in various high-speed train car shells. 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-...

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Problems solved by technology

[0006] However, these steel plates do not involve cold forming when the entire plate is cold-formed at 90 degrees in the length direction and width direction; secondly, the Cr element greatly reduces the strength of the ferrite + pearlite microstructure controlled-rolled steel plate and reduces the yield strength. The magnitude is greater than that of reducing the tensile strength (see "Xishan Memorial Technical Lectures" 86-87, P11), and there are great difficulties in producing high-processability, high-toughness and high-weathering steel plates by controlled rolling technology; at the same time, a large number of patent documents only illustrate How to realize the low-temperature toughness of the base metal steel plate, how to obtain excellent low-temperature toughness of the heat-affected zone (HAZ) under welding conditions is less explained, especially how to ensure the low-temperature toughness of the heat-affected zone (HAZ) when welding with large input energy very few

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