Method for manufacturing low alloy steel tube of low-temperature pressure vessel

Abstract

The invention discloses a method for manufacturing a low alloy steel tube of a low-temperature pressure vessel, which is realized by the following steps: cutting into strips, i.e. vertically cutting a steel plate; milling edges, i.e. milling the two side edges of the steel plate at a time; prebending, i.e. removing straight flanges of the end of the plate; bending, i.e. primarily bending the steel plate into a cylinder shape; molding, i.e. molding the cylinder-shaped steel plate into the steel tube; closing a joint and prewelding, i.e. carrying out joint close on the connecting end of the steel tube; internal welding, i.e. welding the inner part of the connecting end of the steel tube; external welding, i.e. welding the external part of the connecting end of the steel tube; machining a tube end, i.e. machining a flat end of the tube end of the steel tube; straightening, wherein straightness accuracy being up to standard can be reached only through straightening; finishing, i.e. forcibly finishing through an O-shaped mould; trimming an end, i.e. enabling the end of the steel tube to be smooth; final detecting, i.e. detecting the steel tube; and warehousing, i.e. warehousing after the steel tube is detected to be qualified. A measure for preventing unqualified lower temperature impact toughness is controlling welding parameters. Controlling voltage endurance of the steel tube refers to carrying out bulk heat treatment on the steel tube after welding.

Description

technical field [0001] The invention relates to a method for manufacturing steel, in particular to a method for manufacturing low-alloy steel pipes for low-temperature pressure vessels Background technique [0002] With the development of the low-temperature pressure vessel industry, low-alloy steel for low-temperature pressure vessels (especially low-alloy steel for 16MnDR type low-temperature pressure vessels) is being used on a large scale in the manufacture of bridges. Traditional low-alloy steels are no longer suitable for the main parts of the project. 16MnDR low-temperature pressure vessel low-alloy steel is actively used in the bridge manufacturing industry, but due to the difficulty of manufacturing and welding its steel pipes, major design institutes and manufacturers dare not use it easily. In addition, the yield strength of 16MnDR type low-temperature pressure vessel low-alloy steel (its chemical composition is shown in Table 1) is ≥315Mpa, and the tensile streng...

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Problems solved by technology

[0005] In order to solve the technical problems of high strength and hardness of low-alloy steel for low-temperature pressure vessels in the prior art, difficulty in forming, and high possibility of cracks after welding, the invention provides a method for manufacturing low-alloy steel pipes for low-temperature pressure vessels

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