A kind of quenched and tempered coiled tubing steel, hot-rolled steel strip, steel pipe and manufacturing method thereof

Abstract

The invention discloses a quenched and tempered steel for coiled tubing, which contains the following chemical elements in the following mass percentages: C: 0.15-0.35%, Si: 0.08-0.30%, Mn: 0.50-1.80%, P≤0.015% , S≤0.005%, Cr: 0.40‑0.80%, Nb: 0.01‑0.05%, Ti: 0.01‑0.03%, Mo: 0.05‑0.38%, B: 0.0003‑0.0015%, Ca: 0.001‑0.004%, Al: 0.01‑0.05%, 0<N≤0.006%. In addition, the invention also discloses a hot-rolled steel strip made of the above-mentioned quenched and tempered steel for coiled tubing, and discloses a manufacturing method of the oil casing. In addition, the present invention also discloses a steel pipe made from the above-mentioned hot-rolled steel strip. The quenched and tempered coiled tubing steel according to the present invention effectively controls the alloy cost, and the hot-rolled steel strip produced by the steel has low strength. Has good shape, toughness and processing properties. The steel pipe prepared from the low-strength hot-rolled steel strip in the present invention has ultra-high strength, uniform structure and properties, and good fatigue life and corrosion resistance.

Description

technical field [0001] The invention relates to a metal material and a manufacturing method thereof, in particular to a steel grade, a steel strip, a steel pipe and a manufacturing method thereof. Background technique [0002] Quenched and tempered coiled tubing (CT) is relative to conventional threaded tubing, which is a jointless coiled tubing formed by mitering several sections of steel strips, rolled, formed and welded. Known as coiled tubing, coiled tubing, coiled tubing, or coiled tubing. The advantages of coiled tubing in oilfield operations are very prominent. It has developed rapidly in the past ten years and is widely used in oil and gas field workover, drilling, completion, logging and other operations. It is known as the "universal operating machine". [0003] With the development of oil and gas operations and the advancement of drilling and completion technologies, deep wells, high-pressure wells, and horizontal wells have gradually increased. At present, there...

AI Technical Summary

Problems solved by technology

The effect of conventional alloying and controlled rolling and controlled cooling processes is also quite limited. If more alloys are added, the cost will increase significantly, and the low-temperature coiling process will cause severe performance fluctuations in the steel strip.

In addition, even if the ultra-high-strength hot-rolled steel strip is obtained, it will have a greater test on the capabilities of the pipe-making equipment, and there will be certain risks

Therefore, the development of ultra-high strength coiled tubing is still relatively difficult

In addition, the current conventional coiled tubing generally only undergoes simple stress relief annealing after the pipe is made. There is a big difference between the structure of the weld and the pipe body, and the welded part has a large residual stress and is more susceptible to corrosion. Failures often occur here

With the improvement of the strength grade of coiled tubing, the fatigue life of the weld seam tends to decrease relative to the pipe body, which has also become a bottleneck for the further improvement of the strength of conventional coiled tubing

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