Thick-wall high-strength high-toughness oil casing pipe and manufacturing method thereof

Abstract

The invention discloses a thick-wall high-strength high-toughness oil casing pipe which comprises the chemical elements in percentage by mass: 0.22 to 0.30 percent of C, 0.1 to 0.4 percent of Si, 0.5to 1.2 percent of Mn, 0.8 to 1.3 percent of Cr, 0.6 to 1.2 percent of Mo, 0.02 to 0.06 percent of Nb, 0.2 to 0.3 percent of V, 0.02 to 0.06 percent of Ti, 0.0015 to 0.005 percent of B, 0.01 to 0.05 percent of Al, 0.0005 to 0.005 percent of Ca, and the balance Fe and inevitable impurities. The invention further discloses a manufacturing method of the thick-wall high-strength high-toughness oil casing pipe. The manufacturing method of the thick-wall high-strength high-toughness oil casing pipe comprises the steps of (1) smelting and continuous casting; (2) perforating and continuous rolling; and(3) adopting heat treatment processes for two times, wherein during heat treatment for the first time, a two-phase region quenching process is adopted, so that austenite formed by dispersed distribution of a two-phase region is quenched so as to form martensite, and other tissues keep as bainite; and during heat treatment for the second time, a process of water quenching and tempering after complete austenitizing is adopted. The thick-wall high-strength high-toughness oil casing pipe provided by the invention is low in cost, has high strength and high toughness at the same time, and can meetthe demand of an oil field on high-performance oil well pipes.

Description

technical field [0001] The invention relates to an oil casing and a manufacturing method thereof, in particular to a high-strength and high-toughness oil casing and a manufacturing method thereof. Background technique [0002] In recent years, more and more wells have been developed in the field of petroleum exploration and development, including deep wells and ultra-deep wells. In order to ensure the safety of high-temperature and high-pressure production and development, high requirements are placed on the strength of pipe string materials. [0003] As the strength of steel increases, the toughness generally decreases. Insufficient toughness can easily cause early cracks and fractures. Therefore, high-strength casing steel must match higher toughness to ensure the safety of the pipe string. However, thick-walled pipes (with a wall thickness of 20mm or more) have higher requirements on the hardenability of materials, and more martensitic structures need to be obtained after...

AI Technical Summary

Problems solved by technology

[0004] According to the guidance standards of the British Department of Energy, the impact toughness of pressure vessel steel pipes should reach 10% of its yield strength value, the toughness required for 155 steel grade casing materials should reach 107J or more, and the strength of casings that can be used in industrial applications can reach above 155ksi , but the impact toughness is only 50-80J, it is extremely difficult to develop steel with high toughness and high strength

[0005] The patent number is CN101586450A, and the publication date is November 25, 2009. The Chinese patent document titled "High-strength and high-toughness oil casing and its manufacturing method" discloses a high-strength and high-toughness oil casing. Its manufacturing method adopts different heat treatment processes to obtain high-strength steel of about 1100MPa, but its transverse impact toughness is only 90J

Images