What is CT90 ？

CT90 means coiled tubing with a minimum yield strength of 80,000 psi in American strength units (80,000 psi is equivalent to 555 MPa). Molten steel and inclusions control purity

The material has high resistance to fatigue cracking, so the purity of the molten steel is required to be high, and the inclusion levels of A, B, C, and D are all required to be no more than 0.5.

Chemical composition of CT90

Grade

 

CT90
Chemical compositionC%Si%Mn%Nb%Ti%Cu%Ni%Cr%Mo%
0.040.241.380.110.0120.240.150.580.33

Mechanical properties of CT90

High Strength Coiled Tubing

Grade

Yield Strength, MPa

Tensile Strength, MPa

Elongation, %

Hardness, HRC

CT90

≥620

≥669

≥22

≤22

Advantages of CT90 technology

(1) Optimized design of chemical composition;

(2) Purity steel production and inclusion control technology that meet the quality requirements;

(3) Key technologies for microstructure design and control that meet high-strength, low-yield ratio performance;

(4) Controlled rolling, controlled cooling and non-quenching and tempering production process parameters optimization; mainly including: heating temperature, final rolling temperature, post-rolling cooling speed, deformation amount and deformation rate, etc.;

Summary of Steel Used for CT90 Coiled Tubing and Pipe Making at Shanxi Iron and Steel Co., Ltd.

(1) Coil mechanical performance test: Due to the wrong sampling position, the 1-10 meters of the outer ring of the pickling coil supplied is the uncooled section of the first 10 meters of the hot-rolled strip head, and the measured performance cannot be used as the actual coil performance. It is recommended to remove 10 meters after the pickling plate roll in the next supply;

(2) The 180° bending test of the coil is qualified, and the microhardness, band structure, inclusions, and grain size all meet the requirements of the agreement;

(3) The results of the flaring test and the low cycle fatigue test are all qualified;

(4) The test results of the mechanical properties of the test tube meet the requirements; the hardness value of the base material of the test tube meets the index requirements; the hardness value meets the index requirements.

Development trend of coiled tubing and its steel

At present, the coiled tubing at home and abroad mostly adopts CT80 grade. The US QT Company and Tenaris have developed CT110 steel grade coiled tubing, and CT90 has been applied in batches

The application of CT90 and above coiled tubing will be the focus of the development of coiled tubing technology in the near future. For coiled tubing steel, its follow-up development target should be CT90 and above.