Thick steel plate capable of being welded at large heat input and manufacturing method thereof

Abstract

The invention provides a thick steel plate capable of being welded at a large heat input and a manufacturing method thereof. The manufacturing method comprises the following steps: (1) smelting and casting, wherein the thick steel plate is prepared from the following components in percent by weight: 0.05-0.09% of C, 0.10-0.30% of Si, 1.2-1.6% of Mn, not greater than 0.02% of P, 0.001-0.006% of S, 0.2-0.4% of Ni, 0.15-0.3% of Cu, 0.005-0.03% of Ti, 0.0005-0.01% of Mg, 0.001-0.006% of N, not greater than 0.05% of Al, not greater than 0.005% of Ca, not greater than 0.02% of REM, and not greater than 0.003% of B and the balance of Fe and unavoidable impurities, and Ti / N is no less than 1 and is not greater than 6, and Mg / (Al+Ti) is no less than 0.02; (2) rolling; (3) cooling. According to the thick steel plate capable of being welded at the large heat input and the manufacturing method thereof, tiny dispersion-distribution inclusion can be formed; by controlling the (Mg+Ca) / (Al+Ti) ratio and the surface density of micron inclusion with the diameter of no less than 1 micrometer and the (Mg+Ca) / (Al+Ti) ratio and the surface density of sub-micron inclusion with the diameter of 0.1-1 micrometer, a base metal with the tensile strength of no less than 510 MPa is obtained; when the welding heat input is 200-400 kJ / cm, the average charpy impact energy of the steel plate at -40 DEG C is more than 50 J.

Description

Technical field [0001] The present invention relates to the technical field of manufacturing thick steel plates for welding, in particular to a thick steel plate that can be welded with large heat input and a manufacturing method thereof. For steel plates with a plate thickness of 50 to 70 mm and a base material tensile strength ≥ 510 MPa, the welding heat input Under the condition of 200-400kJ / cm, the welding heat-affected zone of the steel plate has good impact toughness, and the average Charpy impact energy at -40°C is above 50J. The thick steel plate can be used as a welding structural material in fields such as ships, buildings and marine structures. Background technique [0002] For ships, buildings, marine structures and other fields, structures are usually constructed by welding steels together. The steel used for these structures not only requires the strength and toughness of the steel, but also requires the steel to have good properties after the welding process. The ...

AI Technical Summary

Problems solved by technology

However, titanium oxide has two major problems: the small amount and the difficulty of dispersing in steel.

If it is desired to increase the amount of titanium oxide by increasing the titanium content in the steel, it will inevitably lead to the formation of large titanium oxide inclusions

When the size of titanium oxide particles is greater than 5 μm, it will reduce the impact toughness of the base metal and welding heat-affected zone

Therefore, in the process of large input energy welding with welding input energy greater than 200kJ / cm, titanium oxide alone is still not enough to improve the toughness of the welding heat-affected zone

Images