A low yield ratio anti-sulfide stress corrosion 345mpa low temperature pressure vessel steel plate and its preparation method

Abstract

The invention discloses a low-yield-ratio sulfide-stress-corrosion-resistant 345-MPa-grade steel plate for a low-temperature pressure vessel. The steel plate comprises the following chemical components in percentage by mass: no more than 0.20% of C, 0.01-0.10% of Si, 1.00-2.00% of Mn, no more than 0.008% of P, no more than 0.003% of S, no more than 0.01% of Nb, no more than 0.035% of Alt, no morethan 0.01% of V, no more than 0.02% of RE, 0.10-0.50% of Ni, and the balance Fe and inevitable impurities. The steel plate disclosed by the invention has the beneficial effects that by adoption of thecomposition design of low carbon, low silicon and micro-alloying elements as well as through a combination with the TMCP rolling process, the yield ratio of the steel plate is lower than or equal to0.65, the elongation reaches 35% or above, and the low-temperature impact toughness at negative 40 DEG C reaches 150 J; furthermore, the sulfide stress corrosion resistance, the weldability and the low welding crack sensitivity are higher; and the involved preparation process is simple, no heat treatment process is needed, and the steel plate is suitable for popularization and application.

Description

technical field [0001] The invention belongs to the field of pressure vessel steel manufacturing, in particular to a low-yield-ratio anti-sulfide stress corrosion 345MPa low-temperature pressure vessel steel plate and a preparation method thereof. Background technique [0002] Yield strength ratio is the ratio of yield strength to tensile strength of steel, which reflects the ability of steel to resist stress concentration during plastic deformation. The lower the yield ratio, the higher the uniform elongation of the steel, the more the steel can evenly distribute the plastic deformation to a wider range, and the safer it is as a structural component. At present, the steel types that require higher yield strength ratio are mainly bridge, construction and pipeline steel, and the service conditions are mostly at room temperature. More stringent requirements are put forward for the yield-to-strength ratio. [0003] Pressure vessel steel has been widely used in all aspects of ...

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Problems solved by technology

[0004] Chinese patent 201611152263.X discloses a steel plate for pressure vessels with a yield strength of 345MPa. ≤0.002%, Al0.020~0.040%, Nb0.020~0.035%, O≤0.003%; this patent mainly achieves low yield ratio and high plasticity by adding a small amount of Nb element and combining heat treatment process, but it can only meet- Performance requirements at 10°C operating environment (conventional 345MPa pressure vessels are usually operating at -40~60°C)

Chinese patent 200810200100.3 discloses a high-strength low-yield ratio steel plate, the main components of which include: C0.15-0.20%, Si1.0-2.0%, Mn1.8-2.0%, Al≤0.036%, V0.05~ 0.10%, P≤0.01%, S≤0.005%, Cr0.8~1.0%; this patent adopts low alloying treatment and obtains a hot-rolled steel plate with high strength and low yield ratio through traditional TMCP rolling process; However, its strength is high, and its low-temperature impact toughness is poor, which cannot meet the use environment of low temperature.

Chinese patent 201110320517.5 discloses a method for manufacturing a high-toughness steel plate with a yield strength of 345-390 MPa. The high-toughness steel plate with excellent mechanical properties is prepared through composition design and process improvement; ≥0.70, poor elongation

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