A kind of ultra-thick q355 grade good low-temperature toughness hot-rolled h-shaped steel and its production method

Abstract

The invention discloses an ultra-thick Q355 grade hot-rolled H-shaped steel with good low-temperature toughness and a production method; the chemical composition of the H-shaped steel according to the invention includes C: 0.12-0.18%, Si: 0.10-0.50%, and Mn: 1.20~1.60%, Al: 0.02~0.06%, Nb: 0.02~0.06%, N: 0.0040~0.0100%, P≤0.015%, S≤0.005%, the rest is Fe and unavoidable impurities, and its flange thickness t 80-150mm, CEV≤0.42%, Pcm≤0.25%; the invention proposes a low-cost component design scheme for Nb and Al microalloying, cooperates with a reasonable continuous casting process and rolling process, and regulates AlN and NbC in continuous casting The distribution of billet and H-shaped steel improves the structure of special-shaped billet and refines the structure of H-shaped steel. The product has good mechanical properties and good economic benefits.

Description

Technical field [0001] The present invention relates to the field of steel production, and in particular, ultra-thick Q355, good low temperature toughness hot rolled H-type steel and production methods. Background technique [0002] Hot-rolled H-type steel is one of the main structures of steel and is an important role in socio-economic development. With the economic development and scientific and technological advancement, high-rise buildings, marine platforms, large-scale railway traffic, large bridges and other construction, high-quality, high performance, and green chemical requirements are proposed for hot rolled H-shaped steel. In general, the thicker thickness of steel material products, the more intensity and toughness are more difficult. my country is currently a blank, the H-shaped steel product of the thickness of 80-150mm is still blank, and the H-shaped steel used is usually made of thick plate welding, the production process is complex, the environmental pollution i...

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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