Low-cost composite rare earth structural steel and production method thereof

Abstract

The invention provides low-cost composite rare earth structural steel and a production method thereof, and relates to the technical field of metallurgy, the low-cost composite rare earth structural steel has a microalloying effect by adding an appropriate rare earth compound, the adding amount of precious metal elements can be reduced, grains are refined, precipitation strengthening is achieved, and the strength, plasticity and low-temperature toughness of the material are improved; the method comprises the following steps: converter treatment: the end point carbon content is greater than 0.04%, and the end point temperature is 1640 + / -15 DEG C; refining: calcium treatment is performed; RH vacuum treatment: rare earth is added, vacuum circulating re-pressing and soft blowing are performed,and then steel is fed; continuous casting treatment, specifically, the liquidus temperature is 1521 DEG C, the superheat degree of molten steel in a first tundish is 25-35 DEG C, and the casting speed is 1.0-1.2 m / min; hot rolling, wherein the heating temperature of the plate blank is 1180-1220 DEG C; the in-furnace time is 180 to 300 minutes; and rough rolling, finish rolling and cooling are conducted in sequence. The technical scheme provided by the invention is suitable for the production process of the structural steel.

Description

【Technical field】 [0001] The invention relates to the technical field of metallurgy, in particular to a low-cost composite rare earth structural steel and a production method thereof. 【Background technique】 [0002] In the 21st century, the market has gradually put forward higher requirements for high strength, high toughness and product reduction development. It is required that structural steel should have the ability to withstand brittle failure and seismic strength of large buildings and ships in service. It is used in construction machinery, hoisting machinery equipment, ships, pipeline steel and other fields. As a series of cheap microalloying elements, rare earth elements act as a mechanism for purifying molten steel and modifying inclusions in steel, thereby refining the target grain structure, effectively improving the strength, plasticity and toughness of the material, and developing a low-cost Rare earth structural steel products. [0003] Patent 201310669853.X ...

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Problems solved by technology

[0003] Patent 201310669853.X discloses a rare-earth-treated high-strength steel plate for construction machinery, which has good low-temperature impact performance and Z-direction performance. After rare-earth treatment, the shape of inclusions is changed, the structure and grain are refined, and the yield strength is greater than 460MPa, -20 The low-temperature impact toughness is greater than 200J at ℃, but it does not involve reducing the amount of other alloying elements, and the cost of raw materials is high

[0004] Patent 201811397212.2 discloses a rare earth treated Q450NQR1 type steel for railway carriages and its preparation method. It mainly explains that adding rare earth elements on the basis of the national standard makes the steel plate have excellent corrosion resistance and improves the service life of the product. There is no research on the replacement of rare earth Or the performance change of a small amount of replacement of one of the precious metals, the research is too single, and it is not conducive to the development of low-cost industrial requirements

[0005] Patent 201811335977.3 discloses a rare-earth-treated low-temperature-resistant X80M pipeline steel and its preparation method. In order to ensure the safe operation of the pipeline at low temperature, adding rare-earth elements can improve the low-temperature impact performance and drop-weight shear area of ​​the material, but does not elaborate on the role of rare-earth elements. Mechanism

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