Austenitic stainless steel continuous tube with low carbon and high strength and preparation method thereof

Abstract

The invention discloses an austenitic stainless steel continuous tube with low carbon and high strength and a preparation method thereof. The austenitic stainless steel continuous tube comprises the components in percentage by mass: at most 0.03% of C, at most 1.00% of Si, 4.00-8.00% of Mn, at most 0.050% of P, at most 0.005% of S, 18-20% of Cr, 3-5.0% of Ni, 1.2-3.5% of Cu, 0.20-0.30% of N, at most 0.3% of Mo and the rest Fe and unavoidable impurities. The preparation method comprises the steps of (1) manufacturing a coil plate; (2) longitudinally shearing the coil plate and lengthening a steel band; and (3) forming the steel band, using laser welding, conducting rapid cooling after welding, and thus obtaining the stainless steel continuous tube. The produced continuous tube has high strength, low cost and good corrosion resistance by optimizing the alloy content and improving the manufacturing process.

Description

Technical field: [0001] The invention belongs to the technical field of petroleum and natural gas pipes, and relates to a low-carbon high-strength austenitic stainless steel continuous pipe with high strength, low cost and good corrosion resistance and a preparation method thereof. Background technique: [0002] Coiled tubing (CT, Coiled tubing) is different from conventional threaded oil pipes. It is a new type of oil pipe with a single length of several kilometers and no threaded connections. It is wound on a reel for transportation and use. With cooperation, it can carry out dozens of operations in the fields of oil and gas field workover, well logging, drilling, well completion, oil and gas transportation, etc., and plays an important role in oil and gas field exploration, development, operation, and production increase. It is called "universal pipe" and is The research and application hotspots in the field of oil and gas operations in the world. [0003] At present, th...

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Problems solved by technology

However, this method has the following problems: (1) When the weld is heated, the base metal on both sides of the weld will form a heat-affected zone, and the heat of the weld will extend the heat shadow zone to continuously expand, causing part of the heat shadow zone base metal to be in austenite Within the range of stainless steel sensitization temperature (400-850°C), the base metal is easy to form M 23 C 6 Intermetallic compounds, such as intermetallic compounds, reduce the plasticity of the pipe string and easily form cracks, and greatly reduce the corrosion resistance of the pipe string

(2) When the welding seam is heated by medium-frequency induction, the strength of the austenitic stainless steel weld seam and the heat-affected zone will decrease significantly, and the compressive performance of the pipe string will be greatly reduced, directly affecting the performance of the pipe string

(3) When the welding seam is heated by medium frequency induction, nitrogen with a purity ≥ 99.7% is used for continuous gas protection, which is easy to form a nitriding layer on the surface of the weld seam, resulting in an increase in the hardness of the weld seam and a decrease in plasticity