A special thick plate produced under low compression ratio and its production method

Abstract

The invention discloses an extra-thick plate produced under a low compression ratio condition and a production method thereof. A continuous casting billet is formed through molten iron converter smelting and an LF+RH refining process, and then the extra-thick plate is formed through a heating process, a one-stage rolling process and a heat treatment process; and the extra-thick plate comprises C,Si, Mn, P, S, Nb, Ti, Alt and Fe elements and inevitable impurities. The 150 mm Q390 extra-thick plate prepared through the production method has the advantages that both the minus 40 DEG C longitudinal impact energy and the minus 60 DEG C longitudinal impact energy are greater than 138J, the percentage of area reduction in the thickness direction meets the requirement of Z35, and higher strength,more excellent low-temperature impact energy and excellent percentage of area reduction in the thickness direction of the extra-thick plate are realized under a low cost production process condition.

Description

technical field [0001] The invention relates to the technical field of metallurgy, in particular to an extra-thick plate produced under low compression ratio conditions and a production method thereof. Background technique [0002] Extra-thick plates over 100mm are widely used in construction machinery, and their demand is increasing. Due to the requirements of engineering quality and the limitations of the service environment, extra-thick plates over 100mm must not only have good internal quality, but also have excellent Mechanical properties, welding performance. [0003] At present, steel ingots, composite slabs and continuous casting slabs with a thickness of 350 mm or more are mostly used for the production of extra-thick slabs above 100 mm. The production of extra-thick slabs from steel ingots and composite slabs has the limitations of long process flow and low yield, while continuous casting slabs with a thickness of 350 mm or more The requirements for continuous cas...

AI Technical Summary

Problems solved by technology

[0005] In terms of composition design, a certain amount of Ni alloy is added to extra-thick plates of different steel grades. Although the addition of Ni alloys can effectively improve the low-temperature toughness of steel, the production cost of extra-thick plates is increased because Ni alloys are relatively expensive.

[0006] Of course, there are also extra-thick plates made of Ni-free alloys in the prior art, but the content of Nb in the composition design is relatively high, and the rolling process is relatively complicated. The "Technology of using continuous casting slab to produce extra-thick steel plate under the condition of small compression ratio" was invented. This invention adopts high Nb composition design and 300mm thick continuous casting slab to produce 140mm Q345E-Z35 extra-thick plate, the compression ratio is 2.14, -40 ℃ impact energy below 80J, the margin is small

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