Method for producing thin-wall X70 pipeline steel coiled plate with low cost

Abstract

The invention provides a method for producing a thin-wall X70 pipeline steel coiled plate with low cost. A continuous casting and rolling production process of a medium-thin plate blank is adopted in the method, the thickness of the plate blank is 130 to 170 millimeters, the charging temperature is more than or equal to 800 DEG C, and the heating temperature is 1,100 to 1,150 DEG C. The method comprises the following steps of: after 3 to 5 times of rough rolling, holding the temperature; when the surface temperature of the middle blank is below 950 DEG C, performing rolling in a precision rolling machine, and controlling the temperature of a precision rolling outlet to be between 820 and 790 DEG C; and performing laminar cooling in a cooling mode of quick cooling and then slow cooling, and then performing coiling and air cooling. The steel grade component design is reasonable, does not add V and has low cost; the production process is simple; and by adopting hot charging, low-temperature heating, rolling control and sectional cooling after rolling, the energy consumption is saved, the production period is shortened, the production efficiency is improved, the purpose of reducing the production cost can be fulfilled, and a polyphase structure using fine acicular ferrite as a main component can be obtained so that the mechanical property of thick specification is ensured.

Description

technical field [0001] The invention belongs to the technical field of micro-alloy high-strength pipeline steel and medium-thin slab continuous casting and rolling short-process production technology, and in particular relates to a 13-20mm thick-walled X70 pipeline steel coil and a production method thereof. Background technique [0002] To reduce the cost of oil and gas pipeline transportation, the pressure and pipe diameter of long-distance pipeline transportation continue to increase. In order to ensure the stability and safety of pipeline transportation, long-distance, high-pressure transmission pipelines usually use thick-walled pipes. For example, the "West-East Gas Transmission" pipeline project in my country in 2001 used 14.6mm thick X70 hot-rolled coils, and the "Sichuan-East Gas Transmission" pipeline project in 2007 used 17.5mm thick X70 hot-rolled coils. At present, X70 is the leading pipeline steel grade for gas transmission pipelines in the world, and the thic...

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Problems solved by technology

The patent has the following features: ①Using thin slabs with a thickness of 70-90mm that can only produce X70 coils with a thickness of less than 12mm; The strength ratio is easy to be too high or even impossible to guarantee; ③ The steel does not add Ti, and the coarsening of austenite grains cannot be effectively suppressed during the reheating process and welding process at a temperature as high as 1230 °C

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