Straight welded oil casing pipe and manufacturing method thereof

Abstract

The invention provides a straight welded oil casing pipe comprising the following chemical components in percentage by weight: 0.24-0.28% of C, 0.15-0.30% of Si, 1.25-1.45% of Mn, not more than 0.020% of P, not more than 0.008% of S, 0.010-0.030% of Ti, 0.02-0.05% of Als and not more than 0.008% of N. The continuous casting slab heating temperature is 1180-1250 DEG C; the start rolling temperature is 1050-1150 DEG C; the finish rolling temperature is 800-880 DEG C; the cooling speed is 9-15 DEG C/s; and the coiling temperature is 580-640 DEG C. A manufacturing method of the casing pipe comprises the steps of manufacturing a steel belt into a steel pipe through straight electric resistance welding, heating to 880-920 DEG C, holding the temperature for 30-50 minutes, carrying out water quenching, heating the whole pipe to 550-640 DEG C, holding the temperature for 60-80 minutes, carrying out water-cooling tempering and rapidly cooling after the tempering. The casing pipe provided by the invention has the advantages that material cost can be reduced; the precious alloy resource is saved; the high-temperature temper brittleness is avoided; the molding is easy in the follow-up pipe-manufacturing process; the yield strength is 695-860MPa; the tensile strength is 790-855MPa, the transverse charpy impact energy Akv is greater than 24J at the temperature of 0 DEG C; the pipe body and the weld joint are uniform in performances.

Description

technical field [0001] The invention belongs to the field of high-strength low-alloy steel metallurgy, and in particular relates to an N80Q grade straight seam resistance welded petroleum casing and a manufacturing method thereof. Background technique [0002] Oil casing is one of the most commonly used oil-specific pipes in oil fields. Its consumption is large, reaching 2.5 million tons in 2010 alone. It is an indispensable construction material in oil and gas field drilling operations. Compared with seamless pipes, ERW casings have significant advantages such as uniform wall thickness, high dimensional accuracy, good perforation performance, strong collapse resistance, and low cost. More than half of oil casings in foreign developed countries have been replaced by ERW casings. However, only low-grade ERW casings in China can replace traditional seamless steel pipes. With the emergence of the economic crisis, the price of seamless pipes has dropped, and the development of...

AI Technical Summary

Problems solved by technology

The content of Mn in the casing is slightly low, and the strength tends to fall below the lower limit; without the addition of Ti element, the heated grains are easy to grow; at the same time, no other elements are added to inhibit high-temperature tempering brittleness and rapid cooling after tempering is not mentioned, so the high temperature cannot be effectively controlled Formation of temper brittleness

[0011] In the patents or documents disclosed above, in order to improve hardenability and suppress the generation of high temperature temper brittleness, without exception, more precious alloys Mo, Nb, V are added, and some also add Ni, Cu, so that there are alloys costly defects

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