A low temperature resistant seamless steel pipe for freezing construction and its manufacturing method

Abstract

The invention provides a low-temperature resistant seamless steel tube for freezing construction and a manufacturing method thereof. The low-temperature resistant seamless steel tube comprises the following components: 0.08%-0.16% of C, 0.2%-0.4% of Si, 1.0%-1.6% of Mn, 0.01%-0.04% of Ti, 0.02%-0.10% of V, less than or equal to 0.015% of P, less than or equal to 0.010% of S, the balance of Fe and inevitable impurities and less than or equal to 0.38% of CEV. The manufacturing method comprises the following steps of: smelting in a converter, carrying out external refining, continuous casting and continuous rolling to obtain a tube blank, heating the tube blank in a circular furnace to 1250 DEG C to 1280 DEG C, perforating by using a perforating machine, rolling the tube at the temperature of 1100 DEG C to 1250 DEG C, flattening, sizing and air-cooling to prepare the finished product steel tube, wherein the sizing temperature is controlled at 780 DEG C to 810 DEG C; or carrying out continuous rolling by adopting an MPM (Massive Parallel Machine), wherein the outlet velocity is 2700mm / s, the retained speed is 750mm / s, the temperature for taking off the tube is 1010 DEG C to 1030 DEG C, and the sizing temperature is controlled at 820-850 DEG C. The low-temperature resistant seamless steel tube has uniform and fine grain structure and good low-temperature impact toughness and welding property; the yield strength of the low-temperature resistant seamless steel tube can reach 245 MPa; the impact toughness of the low-temperature resistant seamless steel tube can reach 80J at -45 DEG C; and the low-temperature resistant seamless steel tube is suitable for freezing pipes in coal mine deep shafts.

Description

technical field [0001] The invention belongs to the technical field of steel pipe production, and relates to a low-temperature-resistant seamless steel pipe for freezing construction and a manufacturing method thereof, in particular to a freezing pipe requiring relatively high low-temperature impact performance in coal mine construction with a depth of more than 800 meters. Background technique [0002] Most of the used freezing pipes in the existing freezing construction technology adopt 20# steel pipes, especially in shallow coal mines. However, as the mine depth continues to increase, the ordinary 20# steel pipe has undergone ductile-brittle transition at -10°C, and its impact toughness has dropped below 10J when the temperature drops to -45°C, which cannot meet the demand. Since the freezing temperature decreases correspondingly during the freezing construction of deeper mines, and the stress situation is more complicated, if ordinary 20# steel pipes are still used as fr...

AI Technical Summary

Problems solved by technology

The Chinese patent with the application number 201010550609.8 discloses "a steel for X80 low-temperature pipe fittings and its preparation and application". Through the heat treatment method of quenching and tempering, its low-temperature toughness is improved, which increases the heat treatment process and correspondingly increases the production cost.

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