Production method of high-sulfur phosphorus high-strength steel continuous casting slab for expanding connecting rod

Abstract

The invention discloses a production method of a high sulfur, high phosphorus and high strength steel continuous casting slab for a heaving broken connecting rod. The method comprises the following steps: 1, electric furnace smelting: carrying out rapid heating decarburization and less running slag operation in the early stage, and controlling the phosphorus content at the oxidation end point in a range of 0.030-0.045%; 2, electric furnace flanged bottom center tapping: carrying out remaining steel and remaining slag operation in tapping, and controlling the sulfur content in tapped steel in a range of 0.050-0.060%; 3, LF furnace refining: adopting a low alkalinity slag system, and controlling the sulfur content in molten steel in a range of 0.040-0.050%; and 4, continuous casting: adopting full-protection casting, crystallizing, electromagnetically stirring, and carrying out weak cooling on the obtained continuous casting slab. The adoption of the rapid heating decarburization and less running slag operation in the early stage of the electric furnace smelting guarantees the phosphorus content in the molten steel, and allows ferrophosphorus not to be added to steel, so alloy is saved; the adoption of the low alkalinity slag system in the refining stage guarantees the sulfur component stabilization and reduces the etching of ladle linings; and the P content and the S content in the continuous casting slag are controlled at 0.030-0.050% and 0.035-0.045% respectively, the low power level of the casting slag is not greater than 1.0 level, the oxygen content is not greater than 20ppm, and the surface quality of the casting slab is excellent.

Description

technical field [0001] The invention relates to metallurgical technology, in particular to a production method for continuous casting slabs of high-sulfur phosphorus high-strength steel for expanding connecting rods. Background technique [0002] At present, the high-strength steel used in automotive engine connecting rods is mainly alloy structural steel and non-quenched and tempered steel. Generally, the traditional production process of "electric furnace (converter) smelting-refining-continuous casting (die casting)" is adopted. And the development process requires steel to have high strength while also requiring high toughness. As the light weight of automobiles requires the development of high-strength steel for automobiles, and the processing technology of automobile parts is required to be more energy-saving and consumption-reducing, the processing technology of automobile engine connecting rod expansion breaking and the corresponding steel for expansion breaking conn...

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Problems solved by technology

At present, the materials used for the expansion processing of connecting rods mainly include C70S6 forged steel, SPLITASCO series forged steel, FRACTIM forged steel and S53CV-FS forged steel, etc., because their steel composition is different from that of traditional alloy structural steel and non-quenched and tempered steel. There are large differences, and the continuous casting slabs of steel for expansion connecting rods produced by traditional production processes have the following disadvantages: 1) The composition of the steel is not easy to control, which may easily lead to the instability of the S component; 2) It is necessary to add ferrophosphorus, increasing the alloy cost; 3) severe cracks, it is difficult to produce qualified continuous casting slabs

[0003] The Chinese patent with the publication number CN1664122A proposes "a production method for continuous casting slabs of low-carbon, high-sulfur (phosphorus-sulfur) free-cutting structural steel". Casting machine pouring three-step method, the process is aimed at low-carbon free-cutting steel (1215, etc.), but it is not suitable for high-carbon, high-sulfur, high-phosphorus, high-nitrogen crack-sensitive steels with a carbon content of 0.40-0.60%, and in Refining slag with higher basicity (Ca / SiO 2 ≥4.0) is not conducive to the stability of the S component in the steel; the Chinese patent with the publication number CN1667129A proposes "a production method of sulfur-containing free-cutting non-quenched and tempered steel", and its production process adopts converter smelting-slag retaining and tapping-steel ladle Deoxidation alloying-LF ladle refining-full protection pouring-slab temperature control and cooling control, but because it is smelted by converter double slag method, the phosphorus content at the end of smelting is low, which greatly increases energy consumption. At the same time, CaO is used in the refining process -SiO 2 Low alkalinity slag system (SiO 2 content up to 40.66%) to severely corrode the basic furnace lining ladle

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