An Oxide Reinforced High Heat Input Welded Steel Plate

Abstract

The invention relates to an oxide-reinforced welded steel plate capable of large heat input. The chemical composition of the steel plate includes: C≤0.10%, Si≤0.20%, Mn 1.20-1.80%, Ti 0.01-0.10%, Alt≤0.01%, Als 0.001-0.005%, Mg 0.0005-0.0030%, N≤0.006%, O 0.0010-0.0050%, and the balance is Fe, some alloy elements and unavoidable impurities. In the present invention, a large number of TiOx-MgAl2O4 composite oxide particles with a size of 0.2-2.0 μm are formed in the steel plate by reasonably controlling the proportional relationship among Ti, Al, Mg, O, and N elements, and the welding heat that the steel plate can withstand is input It has been increased to 600~1000kJ / cm, and it can ensure that the impact energy of the welding heat-affected zone -60°C is ≥100J.

Description

technical field [0001] The invention belongs to the field of production of welded steel plates capable of large heat input, and in particular relates to an oxide-enhanced welded steel plate capable of large heat input. Background technique [0002] At present, as the construction of ships, pressure vessels, bridges and other structures is developing in the direction of large-scale and long-span, higher and higher requirements are put forward for welding efficiency. Therefore, many high-efficiency welding methods such as double-wire and multi-wire submerged arc welding, gas-electric vertical welding, electroslag welding, etc. are more and more widely put into industrial applications. However, with the application of such high-efficiency welding methods, the welding heat input has gradually increased from 15 to 50kJ / cm to 70 to 600kJ / cm, and even as high as 1000kJ / cm. The strength and toughness of the welded joints will seriously deteriorate and cannot meet the requirements o...

AI Technical Summary

Problems solved by technology

The disadvantage of this method is that a large amount of precious metal element Ni needs to be added to the steel plate, which greatly increases the cost of the alloy

[0005] The second type is to reduce the C equivalent of the base steel plate through low-carbon and low-alloy design, and to form TiN particles by controlling the Ti / N ratio in the steel to prevent the formation of austenite grains in the coarse-grained region under large heat input welding conditions. grow up, so as to achieve the purpose of improving the low-temperature toughness of the welding heat-affected zone, such as patents CN201110071409, CN201110172661, CN201410643430, etc. The disadvantage of this method is that the welding heat input can only be increased to about 120kJ / cm, and continuing to increase the welding heat input will lead to The high-temperature residence time in the welding heat-affected zone is greatly prolonged, which causes a large amount of TiN particles to dissolve, which cannot effectively control the growth of austenite grains, which seriously deteriorates the toughness of the welded coarse-grained zone, and also leads to the strength of the welded heat-affected zone. reduce

[0006] The third type is to improve the low-temperature toughness of the welded heat-affected zone under the condition of large heat input welding by forming oxide particles of a specific type and size in the steel plate, but this type of method currently has the following disadvantages: ① In During the smelting process, the oxygen content in the molten steel is controlled at a relatively high level (10-600ppm), and Ti is used for deoxidation. When the oxygen content in the molten steel is high, the yield of Ti will be significantly reduced, which requires adding A large number of Fe-Ti alloys lead to waste of Fe-Ti alloys, such as patent CN100523255C; ② Reasonable constraints are not made on the content relationship between Ti, Mg, Al, O, and N elements, resulting in the number of oxide particles formed It is too small, and the proportion of oxide particles that can promote the nucleation of intragranular ferrite is too small, which makes it difficult for the welding heat input to exceed 600kJ / cm, and the low temperature toughness of the welding heat affected zone is difficult to meet the impact toughness requirement of -60 °C , such as patents CN201210062515, CN201010132582, CN201110003621, JP2005-232515A, JP2005-105322A, JP2011-74447A, etc.

[0007] In summary, there is still a lack of a steel plate that can withstand heat input welding of more than 600kJ / cm and can ensure the impact toughness of the welded heat affected zone at -60°C.

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