Low-alloy high-strength large-diameter thick-walled seamless steel pipe and manufacturing method thereof

Abstract

The invention relates to the technical field of metallurgy, and provides a low-alloy high-strength large-diameter thick-walled seamless steel pipe and a manufacturing method thereof. The method comprises the steps of steelmaking, wherein smelting and refining are performed to obtain target molten steel, and ingot casting is performed on the target molten steel to obtain static ingots; pipe billet forging, wherein forging and annealing are performed on the static ingots to obtain pipe billets; pipe rolling, wherein the pipe billets are heated inside an annular furnace at the temperature of 1230-1270 DEG C, holes are formed after heating is performed, and rolling forming is performed through a pipe mill; normalizing heat treatment, wherein normalizing heat treatment is performed on rolled and formed steel pipes, the normalizing furnace discharge pipe temperature is 920-940 DEG C in the normalizing heat treatment process, and the cooling mode is the air-cooling or air-cooling and mist spraying mode. The steel pipe produced through the manufacturing method is uniform in texture, good in performance and capable of achieving high-strength and excellent subzero 20 DEG C low-temperature toughness, in addition, by adopting the simplified production technology, the production efficiency can be improved, the production cost can be lowered, and meanwhile the steel pipe has the good using safety due to the low yield ratio.

Description

technical field [0001] The invention belongs to the technical field of metallurgy, in particular to a low-alloy, high-strength, large-diameter thick-wall seamless steel pipe and a manufacturing method thereof. Background technique [0002] At present, low-alloy high-strength seamless steel pipes are widely used in construction machinery, grid structures and other industries, especially in the fields of marine engineering equipment and port machinery and equipment, the demand for large-diameter thick-walled seamless steel pipes is increasing. [0003] For low-alloy high-strength seamless steel pipe products, the manufacturing methods are also very different according to different strength level requirements and specifications. For large-diameter thick-walled seamless steel pipes, the general manufacturing method is to select a certain composition, after thermal processing, and then through the quenching and tempering heat treatment process to achieve the required strength lev...

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Problems solved by technology

[0005] The purpose of the present invention is to provide a low-alloy high-strength large-diameter thick-walled seamless steel pipe and its manufacturing method, so as to solve the complicated heat treatment process and the scrap rate of the current low-alloy high-strength large-diameter thick-walled seamless steel pipe during manufacture. higher question

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