Steel material for CT80 level coiled tubing and manufacturing method thereof

A manufacturing method and oil pipe technology, applied in the field of oil pipe steel manufacturing, can solve the problems of increasing heat treatment process, increasing cost, etc., and achieve the effect of grain refinement, increase of fineness, and inhibition of grain growth

Active Publication Date: 2013-01-30
LAIWU IRON & STEEL GRP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] At present, the microalloying elements of domestic CT80 steel for coiled tubing all contain Nb, V, and Ti, and the f

Method used

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  • Steel material for CT80 level coiled tubing and manufacturing method thereof

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0024] The specific gravity is 0.11% carbon, 0.30% silicon, 0.70% manganese, 0.50% chromium, 0.25% nickel, 0.13% molybdenum, 0.30% copper and 0.02% niobium for steelmaking. Converter melting, casting into 80mm thick billet. In the smelting process, solid metal calcium cored wire is used for final deoxidation, and controlled rolling and controlled cold rolling are carried out after forming ingots. After 9 passes of controlled rolling and controlled cooling, the starting temperature of the first three passes of rough rolling is 1050 ° C, and the subsequent The six-pass finish rolling start temperature is 900°C, the final rolling temperature is 830°C, the cooling rate is 16°C / s, the final cooling temperature is 550°C, and the steel strip with a thickness of 80mm is finally rolled to a steel strip of 4.5mm. Among the impurities in the steel strip, nitrogen≤0.004%, phosphorus≤0.015%, sulfur≤0.005%, the yield strength is 565MPa, the tensile strength is 685MPa, and the elongation is ...

Embodiment 2

[0026] The specific gravity is 0.12% carbon, 0.35% silicon, 0.80% manganese, 0.55% chromium, 0.18% nickel, 0.14% molybdenum, 0.35% copper and 0.025% niobium for steelmaking. Converter melting, casting into 80mm thick billet. In the smelting process, solid metal calcium cored wire is used for final deoxidation, and controlled rolling and controlled cold rolling are carried out after forming ingots. After 9 passes of controlled rolling and controlled cooling, the starting temperature of the first three passes of rough rolling is 1100 °C, and the subsequent The six-pass finish rolling temperature is 950°C, the final rolling temperature is 850°C, the cooling rate is 17°C / s, the final cooling temperature is 570°C, and the steel strip with a thickness of 80mm is finally rolled to a steel strip of 4.5mm. Among the impurities in the steel strip, nitrogen≤0.004%, phosphorus≤0.015%, sulfur≤0.005%, the yield strength is 565MPa, the tensile strength is 685MPa, and the elongation is 32%. ...

Embodiment 3

[0028] The specific gravity is 0.13% carbon, 0.40% silicon, 0.90% manganese, 0.60% chromium, 0.10% nickel, 0.15% molybdenum, 0.40% copper and 0.04% niobium for steelmaking. Converter melting, casting into 80mm thick billet. In the smelting process, solid metal calcium cored wire is used for final deoxidation, and controlled rolling and controlled cold rolling are carried out after forming ingots. After 9 passes of controlled rolling and controlled cooling, the initial rolling temperature of the first three passes is 1150 ° C, and the subsequent The six-pass finish rolling temperature is 920°C, the final rolling temperature is 880°C, the cooling rate is 18°C / s, and the final cooling temperature is 600°C, and the steel strip with a thickness of 80mm is finally rolled to a steel strip of 4.5mm. Among the impurities in the steel strip, nitrogen≤0.004%, phosphorus≤0.015%, sulfur≤0.005%, the yield strength is 565MPa, the tensile strength is 685MPa, and the elongation is 32%.

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Abstract

The invention belongs to the technical field of tubing steel manufacturing, and particularly relates to a steel material for a CT80 level coiled tubing and a manufacturing method thereof. The steel material comprises the following chemical components in percentage by mass: carbon: 0.11 to 0.13%, silicon: 0.30 to 0.40%, manganese: 0.70 to 0.90%, chromium: 0.50 to 0.60%, nickel: less than or equal to 0.25%, Mo: 0.13 to 0.15%, copper: 0.30 to 0.40 %, niobium: 0.02 to 0.04%, and the balance being iron and inevitable impurities, wherein nitrogen is less than or equal to 0.004%, phosphorus is less than or equal to 0.015% and sulfur is less than or equal to 0.005% in the purities. The manufacturing method comprises the following steps: the alloy is smelted, a solid core metal calcium cored wire is used for final deoxidation in the smelting process, and then the controlled rolling and controlled cooling rolling is carried out after an ingot is formed, and the finished product is a 4.5mm strip. The steel material provided by the invention has the advantages of complete deoxidation, fine grain and uniform microstructure, and better yield strength, elongation and hardness value.

Description

[0001] technical field [0002] The invention belongs to the technical field of oil pipe steel manufacturing, and in particular relates to a CT80 steel material for coiled oil pipe and a manufacturing method thereof. Background technique [0003] Coiled tubing (Coiled Tubing, referred to as CT) is also called flexible tubing, coiled tubing or serpentine tubing. Compared with conventional tubing that is threaded to go downhole, it consists of several sections of flexible tubing with a length of more than 100 meters. The continuous pipe without joints welded by butt welding or skew welding process can reach hundreds of meters or thousands of meters in total length. In recent years, major domestic oilfields have introduced coiled tubing to carry out related oilfield operations, and the dependence on CT technology has gradually increased. [0004] The steel used for coiled tubing was originally mainly carbon steel. Because the strength of CT material at that time was not high, ...

Claims

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Application Information

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IPC IPC(8): C22C38/48C22C38/26B21B37/74
Inventor 李四军张振栋潘文东王惊雷董杰刘相华周海涛
Owner LAIWU IRON & STEEL GRP
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