An economical x70 pipeline steel plate used in extra-thick specification ultra-low temperature environment and its manufacturing method

Abstract

The invention relates to an extra-thick specification economical X70 pipeline steel plate used in an ultra-low temperature environment. The steel plate comprises the following chemical components in percentages by mass: 0.02-0.08% of C, 0.2-0.4% of Si, 0.9-1.7% of Mn, 0.02-0.04% of Al, 0.02-0.08% of Nb, less than or equal to 0.05% of V, less than or equal to 0.2% of Cr, less than or equal to 0.2% of Ni, less than or equal to 0.1% of Mo, less than or equal to 0.2% of Cu, 0.01-0.02% of Ti, less than or equal to 0.0005% of B, less than or equal to 0.006% of P, less than or equal to 0.001% of Si, less than or equal to 0.002% of N, less than or equal to 0.0012% of O, less than or equal to 0.0001% of H, less than or equal to 100 ppm of P+S+[N]+[O]+[H], less than or equal to 0.19% of Pcm and the balance Fe and inevitable impurities. By means of a great compression ratio rolling technology, the effect of refined grains is intensified, strength and toughness loss caused by reduction of alloy elements are remedied, and the steel plate has a better economical benefit.

Description

technical field [0001] The invention belongs to the technical field of metallurgy, and relates to a pipeline steel plate with an extra-thick specification and used in an ultra-low temperature environment and a manufacturing method thereof. Background technique [0002] The economical X70 pipeline steel plate used in ultra-thick ultra-low temperature environments is mainly used in special environments with complex working conditions such as submarine pipelines, tundra, and ultra-low temperature. With the continuous exploitation of petroleum and petrochemical energy, easy-to-recovery energy has been exploited on a large scale , or even dry up. In order to meet the growing demand for energy, the development and transmission of energy in complex environments has been increasing in recent years, and the design requirements and market demand for submarine pipelines and pipelines in alpine regions have continued to increase. Due to the harsh environment of use, more stringent requ...

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Problems solved by technology

The invention patent with the patent announcement number of CN 104357766 A proposes a high-strength and high-toughness pipeline steel for ultra-deep sea and its manufacturing method. Alloy design, Ni content reaches 0.3-0.5%. The article only mentions the impact energy of the steel plate at -20°C and the drop weight at -15°C. There is no description of the impact energy at -60°C and the drop weight at -30°C. It cannot adapt to a lower temperature environment. Use under

The invention patent with the patent announcement number CN 103999324 A proposes a medium-thick plate for large-wall submarine pipelines and a production method, involving a steel plate with a thickness of 20-33mm, a Ni content of 0.15-0.40%, and a steel plate with -15°C impact and -15°C ℃ drop weight, but there is no performance description for -60°C impact and -30°C drop weight, so it cannot be used in a lower temperature environment

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