Large, thick, high-strength and high-toughness TMCP type steel plate and production method thereof

Abstract

The invention discloses a large, thick, high-strength and high-toughness TMCP type steel plate and a production method thereof. The large, thick, high-strength and high-toughness TMCP type steel plate is composed of, by weight, 0.06%-0.08% of C, 0.20%-0.40% of Si, 1.40%-1.50% of Mn, 0.015% or less of P, 0.005% or less of S, 0.020-0.030% of Nb, 0.030%-0.050% of Alt, the balance Fe and inevitable impurities and 0.20% or less of Pcm. According to the steel plate, the components are simple, only a proper amount of microalloy Nb is added, and the precious elements such as V, Ti and Ni are not added; production cost is low, and the probability of large-scale production is increased. The steel plate is of a mixed structure mainly containing bainite, ferrite, pearlite and martensite and has a good comprehensive mechanical property; the steel plate is better in matching of the components and the strength and toughness, and it is guaranteed that the steel plate has the excellent comprehensive mechanical property; particularly, the impact performance of half of the plate in the thickness direction is good at the low temperature of minus 40 DEG C, and the method can be widely used for producing low-temperature-resistant building steel and engineering steel used in extremely cold climate. The method has the advantages that the production cost is low, and the technique is simple; the performance of products is excellent, and the comprehensive mechanical property of the products is stable.

Description

technical field [0001] The invention relates to a high-strength toughness steel plate and a production method thereof, in particular to a TMCP type large-thickness high-strength toughness steel plate and a production method thereof. Background technique [0002] With the rapid upgrading of domestic medium and heavy plate equipment, on the premise of ensuring the mechanical properties of the steel plate, the cost is continuously reduced, the process is optimized, and the production efficiency is improved. At the same time, the TMCP rolling technology has been more widely used. A large number of TMCP medium and thick plates Plate products and production processes are developed and applied to meet the increasing demand for TMCP-type large-thickness low-alloy steel plates in the market. At present, many steel mills at home and abroad have successfully developed TMCP (or TMCP+tempering) as the main delivery status The low-alloy high-strength steel products have successfully repla...

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Problems solved by technology

Various microalloying elements except Nb are added to the composition of the thick plate to improve austenite stability and low temperature performance; however, the designed C content is in the range of 0.015 to 0.18wt%, when C is required to be below 0.05wt% , in the smelting process of ultra-low C steel, it is usually necessary to increase the step of VD residual oxygen decarburization after primary smelting and before refining, which not only increases smelting cost but also prolongs smelting time

[0005] The Chinese patent application with the publication number CN103882297A discloses a 390MPa low-temperature marine steel with excellent toughness and its manufacturing method. It adopts complex microalloy elements Nb and Ti composite strengthening mechanism in composition, and the cost is relatively high; rolling controlled cooling During the process, different cooling rates are adopted, that is, ultra-rapid cooling with a cooling rate greater than 30°C / S is adopted first, and then laminar flow cooling with a cooling rate greater than 10°C / S is adopted, and the redness returns to 580°C-640°C. During the rolling process, it is required to continuously adjust the parameters of the rolling mill, precisely control the matching of rolling temperature and water volume, and have high requirements for the rolling process

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