A kind of cold-rolled steel plate for double-layer welded pipe with tensile strength of 400mpa

Abstract

The invention discloses a cold-rolled steel plate for a double-layer welded pipe with a tensile strength of 400 MPa, and mainly solves the problem that the existing cold-rolled steel plate cannot meetthe technical problem that the explosion pressure value cannot be larger than 110 MPa when the thickness of the manufacturing wall is 0.5-0.6 mm and the outer diameter of the double-layer welded pipeis phi 4.75mm. The cold-rolled steel plate for the double-layer welded pipe with the tensile strength of 400 MPa comprises the following chemical components in percentage by weight of 0.12-0.18% of C, less than or equal to 0.05% of Si, 0.2-0.6% of Mn, less than or equal to 0.025% of P, less than or equal to 0.020% of S, 0.01%-0.06% of Alt, less than or equal to 0.004% of n and the balance of Fe and inevitable impurity elements. The hardness value of the cold-rolled steel plate with the thickness of 0.2 mm-0.30 mm is 55-65 HR30Tm, the surface roughness Ra is 0.6-1.5 microns. The welded pipe manufactured by the cold-rolled steel plate is used for an automobile oil pipe.

Description

technical field [0001] The invention relates to a cold-rolled steel plate for a welded pipe, in particular to a cold-rolled steel plate for a double-layer welded pipe with a tensile strength of 400MPa and a manufacturing method thereof, belonging to the technical field of iron-based alloys. Background technique [0002] Double-layer welded pipe, that is, double-layer rolled welded pipe, also known as Bondi pipe, generally uses a precision steel strip coated with copper on both sides to surround a central mandrel and is crimped at 720°. The high-temperature welding of the wall, and finally cooling, passivation and other processes become a double-layer steel pipe with excellent fatigue resistance and good leak-proof performance. [0003] At present, the manufacturing process of double-layer welded pipe is divided into two types, one is the continuous brazing process of 1-2s short-time brazing directly by resistance heating after pipe making, and then the casing is cooled; the ...

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Problems solved by technology

[0007] The purpose of the present invention is to provide a cold-rolled steel plate for a tensile strength 400MPa double-layer welded pipe and its manufacturing method, which mainly solves the problem of the existing cold-rolled steel plate in the production of double-walled steel pipes with a wall thickness of 0.5-0.6mm and an outer diameter of Φ4.75mm. The technical problem that the burst pressure value cannot meet the requirement of greater than 110MPa in the layer welded pipe

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