Fluorite-magnesium grain cored wire, application of fluorite-magnesium grain cored wire and production process for high heat input welding steel

Abstract

The invention discloses a fluorite-magnesium grain cored wire, application of the fluorite-magnesium grain cored wire and a production process for high heat input welding steel. The cored wire comprises an outer layer and a clad core. Low-carbon steel serves as the outer layer, and the thickness ranges from 0.5 mm to 1.0mm; sustained-release passivated magnesium grains serve as the clad core, and the clad core comprises a sustained-release agent and passivated magnesium grain bodies; and fluorite serves as the sustained-release agent, the sustained-release agent accounts for 5%-90% of the clad core, and the passivated magnesium grain bodies account for 10%-95% of the clad core. The application refers to application of the cored wire in manufacturing of the high heat input welding steel. According to the production process, the sustained-release passivated magnesium grain cored wire with the fluorite serving as the sustained-release agent is fed into molten steel, the absorption rate of Mg is stable, the effect and the utilization rate of Mg are high, slag inclusions are dispersed and abundant, and the slag inclusions containing Mg reach over 80%. By the adoption of the fluorite-magnesium grain cored wire, application and the production process, control is easy, production cost is low, and industrialized mass production of the high heat input welding steel can be achieved.

Description

technical field [0001] The invention belongs to the technical field of low-alloy steel manufacturing, and in particular relates to a fluorite-magnesium grain cored wire and its application and a production process of steel for high-energy-input welding. Background technique [0002] Steel plates are widely used in infrastructure and large structures such as buildings, bridges, pressure vessels, storage tanks, pipelines and ships. The development trend of large-scale and high-rise building components requires that the thickness of the steel plate be increased, and at the same time have higher comprehensive properties, including higher mechanical properties, efficient processing properties, and excellent corrosion resistance and fatigue damage resistance. [0003] However, as the strength of the steel plate increases, its impact toughness and weldability decrease significantly, and the susceptibility to weld cracks increases. In order to improve the welding efficiency of engi...

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Problems solved by technology

[0005] Magnesium metal is a relatively active element with a boiling point of 1107°C. Due to the high temperature of molten steel in the steelmaking process, its vapor pressure is as high as 2.0×10 6 Pa, so the addition of magnesium in molten steel is prone to evaporation loss and oxidation loss. Improper addition will cause strong oxidation reaction and strong splash in molten steel, which is easy to cause safety problems, and it is also difficult to accurately control Mg in steel

European patent EP1052303A2 "Low-alloy high-strength steel with excellent low-temperature toughness when welded with large input energy" introduced the method of using Ti-Mg composite to obtain fine oxide particles in the test steel, but this test method is only suitable for laboratory vacuum smelting furnace smelting

Chinese patent CN 103938065 A "A Method for Compositely Adding Magnesium and Titanium to Steel for Large Energy Input Welding" adopts the method of feeding Mg-Y-Ni alloy wire in the tundish to increase the Mg concentration in the molten steel, and it is inevitable to add Mg at the same time The introduction of other elements, it is difficult to achieve separate adjustment of Mg content

Chinese patent CN 101724774 A "method of adding magnesium in the process of welding thick steel plate with large input energy", and Chinese patent CN 102191356 A "inclusion control method of thick steel plate for large input The Ni-Mg alloy method obtains a stable Mg yield in steel, but this method is suitable for smelting in a small-scale vacuum smelting furnace, and cannot realize the large-scale industrial production of converter-continuous casting, and it will inevitably bring other element, it is difficult to adjust the Mg content and the timing of adding Mg

Chinese patent CN 203048979 U "a solid metal magnesium alloy cored wire for steelmaking desulfurization", although its method is used for steelmaking desulfurization, not for microalloying of steel for high heat input welding, its solid metal magnesium The core of the alloy cored wire is a magnesium alloy, and other metal elements will also be brought in when the molten steel is fed, and the independent control of Mg cannot be fully realized

And it contains Mg93.6%, when this cored wire is fed to molten steel, it cannot achieve flame retardancy

When the cored wire is fed into the molten steel, the cored wire is melted by the molten steel, and the red hot cored end will continue to oxidize strongly, burning the entire cored wire all the time, and cannot be used for actual production

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