Modern pipeline steel belongs to low carbon or ultra-low carbon micro-alloyed steel, is a high technology content and high value-added products, pipeline steel production almost applied to the metallurgical field in the past 20 years all the new achievements in process technology. The current development trend of pipeline engineering is a large diameter, high-pressure gas-rich transport, high cold and corrosive service environment, submarine pipelines, thick-walled, so the current performance requirements for pipeline steel are mainly in the following areas:
(1) high strength. Pipeline steel strength indicators are mainly tensile strength and yield strength. In the requirements of high strength at the same time, the yield strength ratio of pipeline steel (yield strength and tensile strength ratio) also put forward requirements, generally required in the range of 0.85 ~ 0.93.
(2) high impact toughness. Pipeline steel requires that the material should have sufficiently high impact toughness (starting crack, stop crack toughness). For the parent material, when the toughness value of the material to meet the requirements of the stop-cracking, its toughness can also generally meet the requirements to prevent crack initiation.
(3) low toughness and brittle transition temperature. Harsh geographical and climatic conditions require pipeline steel should have a sufficiently low tough-brittle transition temperature. the shear area of state D has become the main control index to prevent brittle damage to pipelines. General specifications require that at the lowest operating temperature F specimen fracture shear area of not less than 85%.
(4) Excellent resistance to hydrogen-induced cracking (HIC) and resistance to sulfide stress corrosion cracking (SSCC) performance.
(5) Good weldability. Good weldability of steel is essential to ensure the integrity of the pipeline and the quality of field welding. One of the most notable features of the recent development of pipeline steel is to continuously reduce the carbon content of steel, with the reduction of carbon content, the weldability of steel has been significantly improved. The addition of trace amounts of titanium suppresses the decline in toughness in the weld-affected zone and achieves the goal of improving weldability. The difficulty and focus of this is high toughness. With the continuous development of oil and natural gas transportation, the requirements for the performance of oil pipeline steel continue to improve, especially the toughness requirements. The improvement of these properties requires the steel impurity elements C, S, P, O, N, H content down to a very low level. High strength, high toughness is obtained through controlled cooling technology bainitic ferrite organization to ensure that, at the same time, should reduce the carbon content in steel and as far as possible to remove non-metallic inclusions in steel, improve the purity of steel. Which requires the carbon content is not higher than 0.09%, sulfur content is less than 0.005%, phosphorus content is less than 0.01%, oxygen content is not higher than 0.002%; conveying acidic media pipeline steel should be resistant to hydrogen embrittlement, the hydrogen content is required to be less than 0.0002%; for the inclusions in the steel, the maximum diameter should be less than 100 μm, and the requirement to control the shape of oxides, to eliminate the effect of bar sulfide inclusions.
Just like you, 70% customers choose long-term cooperation with BBN steel not only for our good product and service quality, good reputation in the international market, but also for our experienced one-stop raw material supply and further steel processing!
