V-N microalloyed Q550 grade medium plate and preparation method thereof

Abstract

The invention aims at providing a V-N microalloyed Q550 grade medium plate and a preparation method thereof which are specific to the condition that in the prior art, the Q550 grade medium plate expensive alloy is in large consumption and the preparation process is complex. The chemical constitutions of the steel are as follows by weight percentage: 0.06 to 0.12 percent of C, 1.20 to 2.00 percent of Mn, 0.10 to 0.50 percent of Si, 0.002 to 0.01 percent of S, 0.003 to 0.01 percent of P, 0.01 to 0.05 percent of Al, 0.06 to 0.15 percent of V, 0.01 to 0.02 percent of N and the balance of Fe and other unavoidable impurities; the preparation method comprises the steps of heating a steel billet to 1000 to 1200 DEG C along with a furnace and performing heat preservation for 3 to 4 hours, and further carrying out hot rolling on the steel billet to form a hot rolled plate being 20 to 50mm in thickness, wherein the beginning temperature and the finishing temperature in a rough rolling stage are respectively 1030 to 1150 DEG C and 980 to 1020 DEG C, and the beginning temperature and the finishing temperature in a finish rolling stage are respectively 908 to 925 DEG C and 820 to 845 DEG C; cooling the plate by water to 545 to 650 DEG C after the hot rolling, and then cooling by air to room temperature. The plate is a high-toughness ultra-low-carbon medium-manganese medium plate, and the metallographic structure of the plate is a fine crystalline ferrite, a pearlite and an acicular ferrite; the method is simple in operation process, has no need of quenching and tempering treatment, and is easy to realize industrial production.

Description

technical field

[0001] The invention belongs to the field of medium-thick plate manufacturing, and in particular relates to a V-N microalloyed Q550 grade medium-thick steel plate and a preparation method thereof. Background technique

[0002] Advanced medium-thick steel plates with high strength, excellent low-temperature impact toughness and good weldability are the preferred materials for steel structures such as bridges, ship hulls, buildings, pressure vessels, coal mines and offshore platforms, among which low-alloy high-strength steel Q550D is mainly used for dynamic Welded structural parts under load, heavy load and repeated loading conditions require high comprehensive mechanical properties and good weldability. Compared with hot-rolled strip steel, due to the limitation of the load and torque capacity of the rolling mill, in the process of controlled rolling and controlled cooling of medium-thick steel plates, it has the characteristics of high rolling temperature, s...

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