X65 pipeline steel and manufacturing method thereof

Abstract

The invention discloses X65 pipeline steel and a manufacturing method thereof, and belongs to the field of ferrous metallurgy. The method comprises the following steps of molten iron KR pre-desulphurization, converter smelting, LF refining, RH vacuum treatment, wire feeding, flexible stirring, plate blank continuous casting, plate blank reheating, rough rolling, intermediate blank temperature holding cooling, precision rolling, steel plate cooling, steel plate straightening and offline stack cooling, wherein in the plate blank reheating stage, the temperature is controlled to 1150-1220 DEG C,and the in-furnace time is not shorter than 1.1 min / mm; the rough rolling temperature is controlled to 1050-1130 DEG C, after rough rolling, the thickness of an intermediate blank is larger than 4 times the thickness of a steel plate, and the thickness of the steel plate is smaller than or equal to 15 mm; the precision rolling temperature is controlled to 980 DEG C or below, the finish rolling temperature is 880-900 DEG C, and the total compression ratio in the precision rolling stage is larger than or equal to 80%. The pipeline steel manufactured through the method comprises the following chemical components of, by mass percent, 0.05-0.09% of C, 0.10-0.30% of Si, 1.30-1.60% of Mn, 0.020-0.060% of Al, 0-0.030% of Nb, 0-0.020% of Ti, 0-0.25% of Cr, 0-0.015% of P, 0-0.005% of S, 0-0.0080% ofN, 0-0.0005% of B, and the balance Fe and inevitable impurity elements; and Ceq is equal to [C+Mn / 6+(Cr+Mo+V) / 5+(Cu+Ni) / 15] and smaller than or equal to 0.4%, and CEpcm is equal to [C+Si / 30+(Mn+Cu+Cr) / 20+Ni / 60+Mo / 15+V / 10+5B] and smaller than or equal to 0.20%.

Description

technical field [0001] The invention belongs to the field of iron and steel metallurgy, and in particular relates to an X65 grade pipeline steel and a manufacturing method thereof. Background technique [0002] As the first choice of clean energy, natural gas is used in an increasing scale in my country. With the continuous development of my country's pipeline construction, the construction and completion of main line projects such as the West-East Gas Pipeline Series, the Fourth Shaanxi-Beijing Line, and the China-Russia East Line, along the pipeline The upgrading of the pipeline network in major cities in China is also gradually carried out. Unlike the main line projects that use high-grade, large-wall-thick X70 / X80 pipeline steel, most of the urban pipeline network uses small pipes of 610 / 813 / 914mm diameter, the steel grade is basically X65 steel grade, and the wall thickness is basically below 15mm. [0003] The production control of thin gauge (thickness ≤ 15mm) X65 pipe...

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Problems solved by technology

[0005] Technical problem to be solved: the purpose of the present invention is to solve the problem of low rolling production efficiency in the existing manufacturing method of X65 grade pipeline steel, and develop a kind of X65 grade pipeline steel and its manufacturing method, which can reduce the production cost. Cost, improve rolling production efficiency, improve pass rate and control performance uniformity

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