Control method of nano-precipitates in thick steel plate for high heat input welding

Abstract

The invention discloses a control method for a nano-scaled precipitate in a thick steel plate for high heat input welding. Deoxidizers are added during smelting and casting of molten steel, wherein the types and the adding sequence for the deoxidizers are that: (Mn+Si), Al, Ti and (Ca+Mg); Mg content is 0.0005-0.007 percent; oxygen level in the molten steel is required to be adjusted during Mg deoxidization; accurate control is performed by adding Fe2O3 powder into a cast ingot casting mould; the amount of added Fe2O3 powder is 0.001-0.008 percent of oxygen content in the molten steel; the volume density of the precipitates of less than 500nm in steel is more than 9.0*107 per cubic millimeter; the average particle size is less than 80.0nm; and the proportion of the precipitates of less than 100nm is more than 75 percent. A large number of nano-scaled precipitates with small sizes are formed by the method and are finely dispersed and distributed in the steel; suppression of austenite grain growth of a welding heat affected zone is facilitated; and the high heat input welding performance of the thick plate is improved.

Description

technical field [0001] The invention relates to the smelting technology of a thick steel plate for high-energy-input welding, in particular to a method for controlling nano-precipitates in a thick steel plate for high-energy-input welding. Background technique [0002] In many fields such as shipbuilding, construction, pressure vessels, oil and gas pipelines, and offshore platforms, improving the toughness of the heat-affected zone of thick steel plate welding has become an increasingly urgent requirement. However, in the welding process of traditional thick steel plates, the strength and toughness of the heat-affected zone of welding decrease significantly with the increase of welding input energy, so improving the high input energy welding performance of thick plates has become a subject of concern. Improving the large heat input welding performance of thick steel plates can not only improve the operating efficiency of shipbuilding, construction, pipeline and other industr...

AI Technical Summary

Problems solved by technology

Fe 3 Although carbide particles such as C, VC, TiC, and NbC, and nitride particles such as AlN and TiN can be finely dispersed in steel, solid solution or growth, cannot well inhibit the growth of austenite grains

al 2 o 3 、Ti 2 o 3 Oxide particles such as oxides, although they can exist stably under the high temperature of the welding thermal cycle without solid solution, but the particle size of these particles is relatively large, and the growth of austenite grains cannot be well inhibited.

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