Hot-rolled flat plate of large-wall thickness deep-sea pipe steel and manufacturing method thereof

Abstract

The invention discloses a hot-rolled flat plate of large-wall thickness deep-sea pipe steel and a manufacturing method thereof, and belongs to the technical field of low-carbon microalloyed steel. The hot-rolled flat plate comprises, by weight, 0.025-0.045% of C, 0.10-0.35% of Si, 1.10-1.40% of Mn, less than or equal to 0.015% of P, less than or equal to 0.003% of S, 0.04-0.07% of Nb, less than or equal to 0.06% of V, 0.010-0.020% of Ti, 0.15-0.40% of Ni, less than or equal to 0.20% of Cr, less than or equal to 0.08% of Mo, 0.010-0.040% of Al and the balance Fe and unavoidable impurities, wherein a ratio of Al / N is greater than or equal to 2. The manufacturing method comprises the following steps of blast furnace molten iron collection, pre-desulphurization of blast furnace molten iron, smelting by a converter, LF+RH refining, plate blank continuous casting, plate blank heating, rolling by 4300 rolling mill, ACC fast-cooling, stack cooling, sampling and examination, and warehousing and transportation. The hot-rolled flat plate has stable mechanical property indexes, good plasticity-toughness matching and excellent corrosion resistance. The hot-rolled flat plate subjected to UOE molding pipe-preparation has performances reaching to an X70 level.

Description

technical field [0001] The invention belongs to the technical field of low-carbon micro-alloy steel, and in particular relates to a hot-rolled flat plate for deep-sea pipeline steel with large wall thickness and a manufacturing method thereof, which are suitable for deep-sea oil and gas transmission pipelines. Background technique [0002] With the rapid development of the world economy and the depletion of terrestrial energy resources, offshore oil and gas exploration has become an upsurge, and pipeline construction extends to areas with harsh environments such as oceans, seismic zones, and polar frozen land. At present, more than 100 countries in the world are conducting offshore oil and gas exploration, more than half of which are in the deep sea. Restricted by exploration, laying, testing, pipeline raw material technology and equipment conditions, the development of oil and gas resources in deep sea areas in my country is in its infancy. Only the pipelines of the Liwan p...

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Problems solved by technology

[0004] Retrieve the relevant documents and patented technologies published before the patent of the present invention, such as the Chinese patent CN102409224 authorized announcement "Hot-rolled steel plate for thick gauge submarine pipeline steel with excellent low temperature toughness and production method", the specification of the continuous casting slab used has not been published, and the thickness of the steel plate is only To 36.3mm, the special sea area still cannot meet the needs of users, and the alloy composition is relatively high, and the price is expensive; another example is the Chinese patent CN102676925 authorized announcement "a large wall thickness submarine pipeline steel plate and its production method", the alloy formula adopts C:0.06 ~0.07%, M0: 0.15%, in order to facilitate rolling and completely penetrate into the core of the steel plate, the heating temperature is as high as 1235°C, higher heating temperature is not good for low temperature toughness, and the Charpy impact energy at -20°C is low, only 300J, In addition, the continuous casting slab with a thickness of 300mm is used to produce thicker submarine pipes, and the compression ratio is limited

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