Low-cost Q550D steel plate and manufacturing method thereof

Abstract

The invention relates to a low-cost Q550D steel plate and a manufacturing method thereof. The manufacturing method comprises the following steps: smelting molten iron in a converter, heating to 1250-1350 DEG C, adding scrap steel, adding aluminum to perform deoxidizing alloying by a single slag technique, and tapping while skimming, wherein the ladle needs bottom argon blowing operation in the tapping process; and after smelting the molten steel in the converter, refining the molten steel outside the LF (ladle furnace), adding manganese iron, ferroniobium, silicon iron, chromium iron and boron iron, carrying out RH vacuum degassing, adding ferrotitanium, sending the molten steel to a casting machine to carry out continuous casting, heating the prepared plate blank, and carrying out descaling, rough rolling, finish rolling, cooling, thermal straightening, heat treatment, shearing, hardening and tempering, sampling, inspection and finished product warehousing. By adopting the low-carbon component design, proper addition is adopted to enhance the hardenable element, thereby enhancing the steel cleanliness and optimally controlling the heat-treatment hardening and tempering technique to manufacture the low-cost Q550D steel plate.

Description

technical field [0001] The invention relates to the technical field of medium and thick plates, in particular to a low-cost Q550D steel plate and a manufacturing method thereof. Background technique [0002] Low-alloy high-strength steel is widely used in various types of construction machinery. With the development of large-scale, high-efficiency, and lightweight construction machinery and equipment, high-strength construction machinery steel is widely used in construction machinery manufacturing. Steel for construction machinery needs to have high strength, good low temperature toughness, good fatigue resistance, good cold forming performance, good welding performance, etc. With the development of technology, many steel mills can produce Q550D at present, and the competition is fierce. In order to seek market and profit space, the manufacturing cost of Q550D must be reduced. [0003] The patent application number "200710093978.7" named "550MPa yield strength low crack sen...

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Problems solved by technology

[0003] The patent application number "200710093978.7" named "550MPa yield strength low crack sensitivity steel plate and its manufacturing method" adopts ultra-low carbon design, the C content is not more than 0.04%, which puts forward higher requirements on the smelting level, and the Mo Precious metals such as Ni and Ni are relatively high, and the alloy cost is too high, so it is not suitable for low-cost production; the patent application number "201110027518.0" named "a low-alloy high-strength steel plate with a yield strength of 550MPa and its production method" has a low alloy cost , using the method of TMCP+steel stacking to produce steel plates with a yield strength of 550MPa, but the internal stress of TMCP steel plates is relatively strong, and the comprehensive performance of the steel plates cannot be significantly improved only by stacking, and moderate tempering must be done; the patent application number is "201110040675.5" Introduced a low-cost production yield strength of 550MPa for "a method of improving the strength and toughness of high-strength steel for coal machinery by using ultra-fast cooling and steel plate self-tempering technology", but it must be given ultra-fast cooling conditions, which cannot be achieved by ordinary ACC its effect

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