Manufacturing method of low-yield-ratio carbon-manganese low-temperature steel

Abstract

The invention discloses a manufacturing method of low-yield-ratio carbon-manganese low-temperature steel. The chemical components of the low-yield-ratio carbon-manganese low-temperature steel comprises, by weight, 0.05-0.09% of C, 0.10-0.40% of Si, 1.30-1.50% of Mn, less than or equal to 0.010% of P, less than or equal to 0.003% of S, less than or equal to 0.010% of Nb, 0.030-0.060% of Al, and thebalance Fe and inevitable impurities. By adopting the design of low-carbon, high-manganese and high-aluminum components, fine quasi-polygonal ferrites and a few acicular ferrites and pearlitic structures through cooperation of the dynamic soft reduction control technology during the continuous casting process and high-temperature heavy reduction and fast cooling control process after rolling during the rolling process. Compared with steel for liquefied petroleum gas tankers, the low-yield-ratio carbon-manganese low-temperature steel has the characteristics of being pure in steel quality, lowin yield ratio, high in toughness and excellent in low-temperature welding performance. The ductile-brittle transition temperature of a steel plate in the thickness direction is lower than minus 80 DEG C, and the postwelding welding performance at minus 70 DEG C is excellent. Moreover, there is no need to add microalloy elements such as Cu and Cr, and the manufacturing cost is low.

Description

technical field [0001] The invention belongs to the field of manufacturing low-alloy structural steel, and in particular relates to a method for manufacturing low-yield-ratio carbon-manganese low-temperature steel. technical background [0002] Liquefied Petroleum Gas (LPG) is widely used for its convenience, cleanliness and less pollution. Due to the increasing demand for civil and commercial liquefied petroleum gas, the global trade volume of liquefied petroleum gas has increased significantly. Correspondingly, the LPG shipping market has also developed accordingly. [0003] As one of the world's four major ship types currently under development, LPG ships mainly transport petroleum hydrocarbons with propane and butane as the main components or their mixture, including chemical products such as propylene and butene. For ordinary transport ships, -40°C is the limit of transportation use, while the normal working temperature of liquid cargo tanks of LPG ships is -55~-60°C....

AI Technical Summary

Problems solved by technology

And at a higher input welding speed, solid solution Nb will increase the tendency of bainite transformation in the HAZ region, which will have a certain impact on the low temperature performance after welding

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