Method for manufacturing ventilated steel tube made of hull steel

Abstract

The invention discloses a method for manufacturing a ventilated steel tube made of hull steel, which comprises 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 the occurrence of longitudinal cracks of a welding seam is controlling circular degree of prebending and prefinishing before internal welding.

Description

technical field [0001] The invention relates to a steel manufacturing method, in particular to a manufacturing method of a marine steel ventilation steel pipe. Background technique [0002] With the development of the shipbuilding industry, marine steel (especially KSTPG42 marine steel) is being used on a large scale in shipbuilding. KSTPG42 marine steel is the standard of Japan Classification Society. At present, Japanese KSTPG42 marine steel ventilation steel pipes are mainly made of seamless steel pipes. However, the manufacturing cost of seamless steel pipe is high and the specifications are limited. The KSTPG42 marine steel ventilated steel pipe developed by our company can replace some seamless steel pipes. The yield strength of KSTPG42 marine steel (its chemical composition is shown in Table 1) is ≥215Mpa, The tensile strength is greater than 370Mpa. The strength and hardness are high, forming is difficult and cracks are likely to occur after welding. The difficulty ...

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Problems solved by technology

[0005] In order to solve the problems of high cost and limited specifications of the seamless steel pipe used in the prior art, difficult forming and toughness of the steel pipe after welding, the present invention provides a manufacturing method of the marine steel ventilated steel pipe

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