Pressure container steel plate resistant to hydrogen induced cracking and manufacturing method thereof

Abstract

The invention relates to a pressure container steel plate resistant to hydrogen induced cracking. The steel plate comprises, by weight, 0.16%-0.20% of C, 0.15%-0.40% of Si, 1.05%-1.20% of Mn, less than or equal to 0.008% of P, less than or equal to 0.002% of S, less than or equal to 0.01% of Nb, less than or equal to 0.01% of V, less than or equal to 0.01% of Ti, less than or equal to 0.0005% of B, and the balance Fe and inevitable impurity elements. The carbon equivalent Ceq is less than or equal to 0.42%, and a calculation formula for the carbon equivalent Ceq is Ceq=C+Mn / 6+(Cr+Mo+V) / 5+(Ni+Cu) / 15. The steel plate is high in strength and low-temperature impact toughness, low in hardness and good in HIC resistance. The steel plate has fine grains and low nonmetal inclusion content, and obvious banded structures do not exist. After long-time simulation of postweld heat treatment at a high temperature, the strength and the low-temperature impact toughness of the steel plate are not obviously weakened.

Description

technical field [0001] The invention belongs to the field of steel plate manufacturing, in particular to a 50mm thick SA516Gr70 (HIC) hydrogen-induced cracking resistance pressure vessel steel plate and a manufacturing method thereof. Background technique [0002] SA516Gr70(HIC) steel plate is mainly used for wet H 2 Petrochemical plants used in corrosive environments. Hydrogen-induced cracking is a common failure form of steel in wet hydrogen sulfide environment, H 2 S reacts with the surface of the steel to generate hydrogen atoms, which diffuse into the steel and accumulate at the metallurgical defects to generate hydrogen molecules, which generate a large internal stress inside the steel, resulting in interface cracking and the formation of hydrogen bubbling. When the pressure of hydrogen As it continues to increase, the small hydrogen bubbles tend to connect with each other, forming hydrogen-induced cracking with step-like features. [0003] in wet H 2 Once the pres...

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Problems solved by technology

The above three heat treatment processes have certain limitations. Although the normalizing + air cooling process is beneficial to the uniform steel plate structure, it is difficult to meet the requirements of the strength of the sample after high temperature and long-term simulation of post-weld heat treatment; To a certain extent, the banded structure of the steel plate is improved, but the effect on improving the strength of the steel plate is not obvious. Since there is no tempering treatment, the surface of the steel plate may produce martensite or bainite structure due to excessive cooling, resulting in low strength and surface hardness of the steel plate. high, which will eventually lead to cracking at the edge of the steel plate during the container manufacturing process; the quenching + tempering process can significantly increase the strength of the steel plate, but due to the high quenching temperature and excessive cooling speed, if the tempering is not sufficient, the structure of the steel plate will be uneven and increase hydrogen induced cracking susceptibility

[0006] Based on the above reasons, this application proposes a hydrogen-induced cracking-resistant pressure vessel steel and its manufacturing method, which is suitable for use in a wet hydrogen sulfide environment. The composition design and production process are simple, and it is suitable for mass production. No correlation with this process was found after searching. patent

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