Hot-rolled H-shaped steel with a thick gauge having a yield strength of 500 MPa grade and its manufacturing method

摘要

The hot-rolled H-shaped steel of the present invention has the following chemical composition in weight percent. Its chemical composition is C: 0.10% to 0.20%, Si: 0.15% to 0.30%, Mn: 0.8% to 1.30%, Nb: 0.02% to 0.05%, V: 0.10% to 0.16%, Ni: 0.40% to 1.0%, P ≤ 0.015%, S ≤ 0.01%, Mo: 0.15% to 0.35%, Al ≤ 0.05%, O ≤ 0.004%, N: 0.01% to 0.02%, and the rest is Fe and unavoidable impurities. be. The present invention adopts the design of a composite microalloyed composition containing medium C, high Ni and high V suitable for normalized rolling, and is stably controlled at 500 MPa or more by a hot rolling H-shaped steel rolling mill. To obtain hot-rolled H-shaped steel for offshore construction with high toughness. The final structure of the H-shaped steel of the present invention is mainly refined pearlite + proeutectoid ferrite, contains a small amount of bainite, and is made of the H-shaped steel by refining the microstructure, strengthening the phase transformation, and strengthening the precipitation. A good effect can be obtained that can realize low temperature impact toughness at -40 ° C of 100J or more under the conditions of high strength and large thickness. [Selection diagram] Fig. 1