Production method of X70 hot-rolled medium plate for submerged pipeline

Abstract

The invention provides a production method of an X70 hot-rolled medium plate for a submerged pipeline. The medium plate comprises the following components in percentage by weight: 0.035 to 0.07 percent of C, 0.10 to 0.35 percent of Si, 1.40 to 1.85 percent of Mn, less than or equal to 0.010 percent of P, less than or equal to 0.0035 percent of S, 0.01 to 0.06 percent of Alt, 0.035 to 0.07 percent of Nb, 0.008 to 0.020 percent of Ti, 0.10 to 0.30 percent of Mo, 0.10 to 0.25 percent of Ni, 0.10 to 0.25 percent of Cr, 0.10 to 0.25 percent of Cu and the balance of Fe and inevitable impurity elements. In the steel plate manufacturing process, the effects of the alloy elements and the potential of an excavation thermo-mechanical control process are fully exerted through an optimized blank type design, a strict heating schedule and a reinforced thermo-mechanical control process in coordination with an appropriate amount of Ni, Cr and Cu alloy elements, so that an organization form based on a uniform fine acicular ferrite is obtained on a steel plate with the whole wall thickness, and the medium plate has relatively high horizontal and longitudinal tensile strength and high low-temperature toughness, and completely meets the requirements of high performance of steel for a deepwater submerged pipeline.

Description

technical field [0001] The invention belongs to the technical field of low-carbon micro-alloy steel production, and in particular relates to a production method of X70 hot-rolled medium-thick plate for submarine pipelines, which is suitable for 25 for submarine pipeline projects with high requirements for transverse and longitudinal tensile strength and low-temperature toughness. ~35mmX70 hot-rolled plate production. Background technique [0002] With the rapid development of the global economy, the demand for oil and natural gas has been in short supply, which has greatly promoted the development of marginal and offshore oil and gas resources and the construction of submarine pipelines. The importance of steel for submarine pipelines has become increasingly prominent. [0003] Submarine pipelines serve in the deep sea and the harsh marine environment, and the pipelines are subjected to deep sea high pressure and severe marine corrosion; and due to the complexity of the subm...

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Problems solved by technology

Patent 200710052601.7 discloses "a steel plate for making submarine pipelines and its rolling method", and proposes a production method of X65 hot-rolled coils for submarine pipelines, which is similar to the production method of X70 hot-rolled medium-thick plates with large wall thickness in this patent In addition, the relevant literature "Development and Application of Steel for Submarine Pipeline" (Welded Pipe. 2006, 29(5): 36-39) only introduced the physical and chemical properties of Baosteel's X65 grade steel plate for submarine pipeline, but did not discuss the properties of the steel plate. Full disclosure of chemical composition and production methods

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