Oil bushing steel and manufacturing process thereof

Abstract

The invention relates to an oil bushing steel and the manufacturing process thereof, wherein, the chemical composition of the steel is as follows: 0.28wt percent to 0.35wt percent of C, 0.1wt percent to 0.4wt percent of Si, 0.8wt percent to 1.6wt percent of Mn, 0.4wt percent to 0.6wt percent of Mo, 0.8wt percent to 1.2wt percent of Cr, 0.05wt percent to 0.10wt percent of V, less than or equal to 0.005wt percent of S, 0.01wt percent to 0.04wt percent of Al and the rest, Fe and other inevitable impurities; the manufacturing process of the steel is as follows: the tube blank made by continuous casting or continuous rolling is perforated by a perforator after heating in a heating furnace and is under tube rolling under 950 DEG C to 1,050 DEG C; the tube blank is fed into a reheating furnace after releasing from a rod and then is fed into a tension-reducing mill or a stretcher after holding under 800 DEG C to 1,000 DEG C for air cooling after rolling; finally, after holding under 860 DEG C to 1,000 DEG C and quenching, the tube blank is under tempering under 600 DEG C to 660 DEG C holding to be made into production tube. The steel has excellent hardenability and higher structural stability and can ensure that an oil well oil bushing not only can obtain 1,000MPa to 1,200MPa yield strength, but also can meet the requirements of more than 70J transverse ballistic work and more than 90J ballistic work.

Description

technical field [0001] The invention relates to a steel for oil and casing, that is, a high-strength and high-toughness oil and casing steel, in particular to a steel with a yield strength of more than 1000Mpa and a transverse impact energy greater than 75J under the condition that the well depth exceeds 5000 meters or the anti-collapse performance is high. , The chemical composition and manufacturing process of steel for oil casing with impact energy greater than 90J. Background technique [0002] As far as the steel types commonly used for oil casing are concerned, the highest strength of API standard is Q125 steel grade, and the longitudinal impact energy is greater than 60J. With the change of oil field production conditions, the deep wells for oil and gas exploitation are getting deeper and deeper, and the ordinary oil casing of Q125 steel grade can no longer meet the needs, and the oil casing with higher strength and better toughness is needed. As the strength of oil ...

AI Technical Summary

Problems solved by technology

Some manufacturers use low-alloy steel materials to produce high-strength oil casings, but finally give up production due to low impact toughness or low strength of materials

[0006] Using high-Cr and Ni alloys for quenching and tempering heat treatment ensures that the various properties of the material can achieve high strength and toughness, but compared with low-alloy steel pipes for the production of oil casings, the production cost is greatly increased and the market competitiveness of the products will be reduced.