A kind of low-temperature resistant micro-alloyed steel and its production process

Abstract

The invention relates to low temperature resistant microalloyed steel. The chemical components of the microalloyed steel comprise, by weight, 0.075%-0.1% of C, 0.10%-0.30% of Si, 1.0%-1.40% of Mn, 0.25%-0.50% of Cr, 0.020%-0.030% of Nb, 0.015%-0.025% of Ti, less than or equal to 0.015% of Al, less than or equal to 0.010% of P, less than or equal to 0.010% of S, the balance Fe and unavoidable impurity elements. The unavoidable impurity elements comprise the gas content and other unavoidable impurity elements, wherein the gas content comprises less than or equal to 2.0 ppm of molten steel [H], less than or equal to 2 ppm of a casting blank [H], less than or equal to 30 ppm of [O] and less than or equal to 50 ppm of [N]; and the other unavoidable impurity elements account for less than or equal to 1%. Meanwhile, the invention further relates to a production technology of the low temperature resistant microalloyed steel. Through a Nb+Ti microalloyed technology, growth of austenite grains is effectively controlled in the heating process of steel rolling, a ferrite-pearlite ultra-fine grain structure is obtained finally, the grain size reaches above the 10th level, and the technical requirements for indexed such as low temperature are met. The yield strength of the microalloyed steel is higher than 355MPa, the tensile strength is higher than 550MPa, -60 DEG C low temperature impact Ak is higher than 27J, and the elongation after breaking is higher than 22%.

Description

technical field [0001] The invention relates to the technical field of construction steel, in particular to a low-temperature resistant micro-alloyed steel and a production process. Background technique [0002] Due to the rapid development of the world economy, the demand for oil and gas in various countries is increasing day by day, and oil and gas exploitation is gradually moving from land to sea, from low temperature to high cold, which puts forward new requirements for the development of steel and H-shaped steel for low temperature resistant steel structures. [0003] In terms of variety development, low-carbon manganese steel C (<0.12%) + (Nb, V micro) alloying technology is generally adopted internationally, which is reflected in Russian standards and European standards. On the microstructure, the process route of fine grain controlled rolling is adopted to ensure the low temperature performance. However, the production of low-temperature-resistant structural stee...

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Problems solved by technology

[0007] In view of the above analysis, the present invention aims to provide a low-temperature-resistant micro-alloyed steel and a production process to solve the problem that transverse cracks are easily produced on the surface of the continuous casting slabs of the existing low-temperature-resistant micro-alloyed steel and H-shaped steel

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