X65 pipeline steel for use in acid condition and its making process

Abstract

The X65 pipeline steel for use in acid condition consists of C 0.02-0.05 wt%, Mn 1.20-1.50 wt%, Si 0.10-0.50 wt%, S not more than 0.0020 wt%, P 0.004-0.012 wt%, Nb 0.05-0.07 wt%, Ti 0.005-0.025 wt%, Mo 0.050-0.195 wt%, Cu not more than 0.35 wt%, Ni not more than 0.35 wt%, N not more than 0.0080 wt%, Ca 0.0015-0.0045 wt% and Ca / S not less than 2.0 except Fe. Its making process includes the following steps: smelting in a converter or an electric furnace; secondary steel making including LF desulfurizing + RH vacuum deairing and Ca treatment; continuous casting; rolling with initial rolling termination temperature of 940-1020 deg.c and finish rolling termination temperature of 780-840 deg.c; and winding at 500-580 deg.c. The X65 pipeline steel has low manufacture cost, high HIC resistance, high dynamic tear resistance and high impact toughness.

Description

technical field [0001] The invention relates to the field of metal materials and plastic processing, in particular to pipeline steel hot-rolled coils and a manufacturing method thereof. Background technique [0002] At present, steel pipes for oil and natural gas transportation in most countries follow the API 5L specification of the American Petroleum Institute, and based on this, supplementary requirements are put forward according to specific pipeline engineering needs. The hot-rolled coil steel or steel plate used to manufacture such welded pipes is commonly referred to as pipeline steel. Pipeline steel is an important material used in long-distance natural gas pipeline engineering. With the adjustment of energy structure and the increase of demand for natural gas, the development of high-pressure gas transmission pipelines has been greatly promoted. The biggest difference between steel for pipelines for transporting natural gas and steel for pipelines for transporting...

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