Submarine X70-grade pipeline steel resistant to hydrogen sulfide corrosion and production method thereof

Abstract

The invention discloses submarine X70-grade pipeline steel resistant to hydrogen sulfide corrosion. The submarine X70-grade pipeline steel resistant to the hydrogen sulfide corrosion comprises the following components of, in percentage by weight, 0.02%-0.03% of C, 0.23%-0.26% of Si, 1.10%-1.20% of Mn, 0.10%-0.15% of Ni, 0.25%-0.30% of Cr, 0.12%-0.16% of Mo, 0.004%-0.006% of Mg, 0.04%-0.07% of Nb,0.03%-0.05% of V, 0.01%-0.02% of Ti, not more than 0.005% of P, not more than 0.002% of S and the balance Fe and inevitable impurities. A production method of the submarine X70-grade pipeline steel resistant to the hydrogen sulfide corrosion comprises the following steps that 1) smelting is carried out in a converter, Mg treatment is carried out in conventional vacuum, and casting and blank forming are carried out; 2) a cast blank is heated, and the heating temperature of the cast blank is controlled to be 1220-1250 DEG C; 3) the starting temperature of rough rolling is 1030-1080 DEG C, the ending temperature of rough rolling is 970-990 DEG C, and the total reduction rate is 65%-75%; (4) the starting temperature of finish rolling is 870-910 DEG C, the ending temperature of finish rolling is 840-870 DEG C, the cumulative reduction rate of finish rolling is not lower than 65%, and a steel plate with the thickness of 12 mm is formed through seven passes of rolling; and (5) laminar coolingis carried out, and the steel plate is cooled to 450-510 DEG C at the cooling speed of 40-60 DEG C / s, and curled for later use. Compared with the prior art, the submarine X70-grade pipeline steel resistant to the hydrogen sulfide corrosion has the advantages of being high in strength, high in toughness and high in hydrogen sulfide corrosion resistance.

Description

technical field [0001] The invention relates to the technical field of pipeline steel, in particular to a hydrogen sulfide corrosion-resistant X70 grade pipeline steel for seabeds and a production method thereof. Background technique [0002] As the country's economic development strategy shifts from land to sea, offshore oil and gas development has risen rapidly. Submarine pipelines are the fastest, most economical and most effective means of transportation for offshore oil and gas, and are a necessary means for my country to develop rich offshore oil and gas field resources. The harsh environmental conditions of the seabed require pipes to have high strength, high toughness, fatigue resistance, corrosion resistance and other properties, and the production technology is difficult. In particular, the transported oil and natural gas often contain acid gases such as hydrogen sulfide, which will cause hydrogen-induced cracking (HIC) and sulfide stress cracking (SSCC) in pipeli...

AI Technical Summary

Problems solved by technology

The Chinese patent document with the Chinese patent application number 201910527675.4 discloses "acid-resistant high-strength pipeline steel for marine ultra-low temperature service and its preparation method", which adopts reasonable composition design and optimized production process to solve the problem of strength and sulfuration resistance of existing pipeline steel products Insufficient hydrogen corrosion performance, low production efficiency, high manufacturing cost and other problems meet the service requirements of high-strength and high-toughness marine corrosion-resistant pipeline steel at a service temperature of -30°C, and overcome the current X70 land-based acid-resistant pipeline steel that cannot meet the seabed anti-corrosion requirements. Technical Defects of Acid Lines

This method also uses Al for deoxidation treatment, and there is more Al in steel 2 o 3 Inclusions, poor resistance to hydrogen sulfide corrosion

[0005] To sum up, in the prior art, in order to reduce the oxygen content in steel in steelmaking, Al is generally used for deoxidation, and Al is generated in molten steel 2 o 3 Inclusions are detrimental to the mechanical properties and hydrogen sulfide corrosion resistance of steel

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