Low-carbon bainite thick steel plate with high strength and toughness and manufacturing method thereof

Abstract

The invention relates to a low-carbon bainite thick steel plate with high strength and toughness and a manufacturing method thereof. The steel plate comprises the following components in percentage by mass: 0.02 to 0.09 percent of C, 0.35 to 0.60 percent of Si, 1.50 to 1.85 percent of Mn, 0.15 to 0.30 percent of Mo, 0.04 to 0.07 percent of Nb, 0.04 to 0.07 percent of V, 0.0010 to 0.0020 percent of B, 0.01 to 0.04 percent of Al, 0.01 to 0.03 percent of Ti, less than or equal to 0.0030 percent of Zr, Mo in an amount which is more than or equal to 0.55-0.181Mn-1.51C and less than or equal to 8.7-3.69 Mn-29.18C, and the balance of Fe and inevitable impurities. The steel plate does not need quenching and heat treatment, so the manufacturing process is simplified, and the manufacturing cost of steel is reduced. The yield strength of the steel plate with low welding crack sensitivity is more than 690MPa, the tensile strength is more than 770MPa, the Charpy impact power Akv (-20 DEG C) is more than or equal to 180J, and the thickness of the plate can reach 80 millimeters. The welding crack sensitivity index Pcm is less than or equal to 0.20 percent, and the steel plate has excellent welding performance.

Description

technical field [0001] The invention relates to the field of high-strength toughness steel plates, in particular, the invention relates to an easy-to-weld high-strength toughness low-carbon bainitic thick steel plate. Background technique [0002] High-strength and tough thick steel plates are widely used in industrial fields such as construction machinery, mining machinery, and port machinery. They need to have the characteristics of high strength, good low-temperature impact energy, and good welding performance. There are usually two technologies for producing high-strength and tough thick steel plates: quenching and tempering heat treatment of steel plates after rolling; stress relief tempering after controlled rolling and controlled cooling (Thermo-mechanical Control Process-TMCP). For thick steel plates with the same mechanical properties, the properties of the steel plates produced by quenching and tempering process are stable, but the alloy composition is relatively h...

AI Technical Summary

Problems solved by technology

Such as the steel grade disclosed in patent application CN101230444, microalloying elements such as Cr, Mo, Nb, Ni, V, B, Al, Ti, etc. are added, but because the content of Cr is too high, the weldability of the steel is affected

Another example is the steel grade disclosed in the patent application WO2008069289, although the content of Cr is reduced, but expensive Ni, Cu, W and rare earth elements are added, which increases the manufacturing cost of the steel plate

According to the calculation formula of welding crack sensitivity index (Pcm), alloying elements such as Cr, Mo, Ni, Cu will increase the Pcm value of the steel plate and reduce its welding performance

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