A kind of manufacturing method of economical pipeline steel

Abstract

The invention relates to a method for manufacturing economical pipeline steel. The element combination of the pipeline steel involved is measured by wt% as C 0.075-0.090, Si 0.3-0.4, Mn 1.75-1.90, Al 0.02-0.04, Nb 0.01-0.025, Ti 0.02‑0.03, [N]0.004‑0.007, S≤0.003, P≤0.015, the balance is Fe and unavoidable impurity elements. The manufacturing method includes BOF converter smelting—RH / VD vacuum degassing—150mm continuous casting slab—continuous casting slab inspection, cleaning, heating furnace—casting slab heating (guaranteed waiting time)—high pressure water descaling—rolling—ACC cooling, etc. . The invention can obtain acicular ferrite + polygonal ferrite mixed structure, yield strength ≥ 485MPa, tensile strength ≥ 570MPa, elongation ≥ 30%, and impact energy ≥ 200J at -40°C.

Description

technical field [0001] The invention belongs to the technical field of iron-based alloy steel, and in particular relates to a method for manufacturing pipeline steel. Background technique [0002] Pipeline steel plates are mainly used in the production of steel pipes for oil, gas and water transportation in long-distance pipeline projects or urban pipeline network projects. Depending on the materials required for different projects, good low-temperature toughness, high strength and weldability are usually required . At present, the mainstream design of pipeline steel plates is low-carbon plus microalloying elements such as Nb, V, Ti, Cr, Ni, Mo, etc., and high-purity molten steel is obtained through BOF+LF+RH refining. In order to ensure the compression ratio, the thickness of the continuous casting slab Usually between 200-300mm; the continuous casting slab is generally treated with slow cooling and hydrogen expansion, and then the cold slab is heated in the furnace. The h...

AI Technical Summary

Problems solved by technology

In the traditional method, the specific engineering requirements are not distinguished, and the quality surplus is considered too much, resulting in high production costs, excessive quality surplus, and poor economy

[0003] Patent announcement number CN105132833B proposes an economical high-strength submarine pipeline steel and its production method, which reduces the production cost by removing a small amount of Mo, but adopts a higher Nb content, reaching 0.05-0.07%, and the cost is still high; while reducing When the Mn content is increased, the comprehensive alloy cost is still high

At the same time, the smelting process adopts BOF+LF+RH, and the hot delivery is not specified in the rolling, and the heating time is too long

[0004] The patent application number is CN201410092713.5, which discloses "an economical X70 oil and gas pipeline steel and its production method", which uses medium and low C, high Mn, and adds alloy elements such as Cr, Nb, V, Ti, etc. Composition design, combined with the manufacturing method of medium and heavy plate TMCP process to produce high-strength X70 pipeline steel, the content of microalloying elements is still high, while the range of Mn elements is low, and the comprehensive alloy cost is high

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