100 mm-120 mm Q460D extra-thick high-strength steel and preparation method thereof

Abstract

The invention relates to 100 mm-120 mm Q460D extra-thick high-strength steel which comprises the following chemical components including, by mass, 0.10% to 0.13% of C, 0.30% to 0.50% of Si, 1.40% to 1.60% of Mn, less than or equal to 0.0070% of P, less than or equal to 0.0020% of S, 0.020% to 0.050% of Nb, 0.008% to 0.020% of Ti, 0.020% to 0.040% of Al, 0.10% to 0.20% of Cu, 0.10% to 0.20% of Cr, 0.10% to 0.20% of Ni and the balance Fe and inevitable impurity elements. The production process flow comprises the following steps of converter smelting, LF refining, RH vacuum degassing, Ca treatment, continuous casting, casting blank dehydrogenation treatment, heating, normalizing rolling, air cooling, steel plate stacking and slow cooling and unstacking. The yield strength of a steel plate ranges from 430 MPa to 470 MPa, the tensile strength ranges from 550 MPa to 570 MPa, the ductility is larger than or equal to 20%, and the Charpy impact energy at the 1/4 position and the 1/2 position of the thickness of -20 DEG C is larger than or equal to 200 J. The flaw detection result meets the ASTM A 578C level requirement, and the surface of the steel plate has no defect.

Description

technical field [0001] The invention relates to a 100-120mm Q460D extra-thick high-strength steel and a preparation method thereof. It belongs to the technical field of iron and steel metallurgy. Background technique [0002] With the continuous development of national large-scale equipment, thick plates and extra-thick steel plates have been widely used in the construction of marine engineering, ships, high-rise buildings, bridges, pressure vessels, energy and chemical industries, and have become important steel materials in the development of the national economy. For high-strength extra-thick steel plates such as Q460D, steel ingots / composite billets are traditionally used for forging or rolling blanks, and then heated and rolled into extra-thick plates. However, the production of steel ingots and composite billets has low yield, low efficiency and high cost, so it is not recommended to use. The production of continuous casting slabs can reduce the cost, but the thickne...

AI Technical Summary

Problems solved by technology

The strong cooling mode and the extremely low final cooling temperature lead to a large internal stress on the steel plate, which affects the later use and welding

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