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Abstract

Provided are a hot-rolled, low-temperature-resistant, H-shaped steel with a grade of 420 MPa and a preparation method therefor. The H-shaped steel comprises the following chemical components in percentages by weight: C: 0.08-0.10%, Si≤0.2%, Mn: 1.25-1.45%, V: 0.03-0.045%, Ti: 0.015-0.025%, Cr: 0.15-0.30%, Als: 0.02-0.04%, N: 0.007-0.01%, P≤0.008%, S≤0.005%, O≤0.004%, and the balance being Fe and inevitable impurities. In the preparation method, the characteristic of the flange of the small-specification H-shaped steel being thin in rectangular blank rolling is combined, the design of a low content of C suitable for normalizing rolling being in cooperation with a V micro-alloyed component is used, an appropriate amount of Cr is added to control the cooling rate, and the situation whereby the low-temperature impact toughness of steel deteriorates due to the occurrence of abnormal structures such as widmanstatten is avoided, thus a stably controlled, high-strength and high-toughness, hot-rolled, H-shaped steel with a grade of 420 MPa or more is obtained on a hot-rolled H-shaped steel rolling mill.

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