Super-thick Q355-grade hot-rolled H-shaped steel with good low-temperature toughness and production method thereof

Abstract

The invention discloses super-thick Q355-grade hot-rolled H-shaped steel with good low-temperature toughness and a production method thereof. The H-shaped steel comprises the following chemical components of, in percentage by mass, 0.12-0.18% of C, 0.10-0.50% of Si, 1.20-1.60% of Mn, 0.02-0.06% of Al, 0.02-0.06% of Nb, 0.0040-0.0100% of N, less than or equal to 0.015% of P, less than or equal to 0.005% of S, the balance Fe and inevitable impurities, with flange thickness of 80-150mm, less than or equal to 0.42% of CEV, and less than or equal to 0.25% of Pcm. The invention further provides an Nb and Al microalloying low-cost component design scheme. With reasonable continuous casting process and rolling process, distribution of AlN and NbC in a continuous casting billet and the H-shaped steel is controlled, a beam blank structure is improved, a H-shaped steel structure is refined, the product mechanical performance is good, and the economic benefits are good.

Description

technical field [0001] The invention relates to the technical field of iron and steel production, in particular to an ultra-thick Q355 grade hot-rolled H-shaped steel with good low-temperature toughness and a production method. Background technique [0002] Hot-rolled H-shaped steel is one of the main structural steels and plays an important role in social and economic development. With economic development and scientific and technological progress, the construction of a series of large-scale engineering structures such as high-rise buildings, ocean platforms, large-scale all-weather railway traffic, and large bridges has put forward performance requirements for large-scale, high-performance, and green hot-rolled H-beams. Generally speaking, the thicker the steel material product is, the harder it is to guarantee the strength and toughness. At present, there is still a blank in my country for ultra-thick hot-rolled H-shaped steel products with a flange thickness of 80-150mm...

AI Technical Summary

Problems solved by technology

At present, the ultra-thick hot-rolled H-shaped steel products with a flange thickness of 80-150mm are still blank in China. The H-shaped steel used is usually welded by thick plates. The production process is complicated, the environment is polluted, and the economic benefits are poor.

[0003] Compared with steel plates, due to the complex cross-section of hot-rolled H-beams, the rolling conditions (rolling temperature, rolling reduction ratio) are limited. 1) The rolling reduction ratio is difficult to adjust, especially for ultra-thick H-beams. The amount of deformation between times is difficult to adjust, and the total compression ratio is small (minimum only 1.5); 2) The cooling rate of each part of the flange, web and transition arc of the H-shaped steel is different during the rolling process, resulting in various parts The rolling temperature difference is large, and the rolling temperature is uneven

Therefore, the ultra-thick hot-rolled H-shaped steel cannot simply learn from the manufacturing process and chemical composition of the steel plate, and it is difficult to guarantee the strength and toughness, and cannot meet the requirements of the GB / T1591 standard.

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