Killed non-tempered steel containing sulfur and aluminum and morphology control method of sulfides thereof

Abstract

The invention provides a killed non-tempered steel containing sulfur and aluminum and a morphology control method of sulfides thereof. The killed non-tempered steel comprises following chemical components in percentage by weight: 0.30 to 0.50% of C, 0.45 to 0.75% of Si, 1.20 to 1.60% of Mn, 0.10 to 0.30% of V, 0.010 to 0.050% of Ti, 0.10 to 0.50% of Cr, 0.020 to 0.080% of S, 0.015 to 0.060% of Al,0.005 to 0.040% of Te, 0.010 to 0.015% of [N], not more than 0.015% of P, not more than 0.0012% of T.O, not more than 0.30% of Ni, not more than 0.15% of Mo, not more than 0.25% of Cu, not more than0.010% of As, not more than 0.010% of Sn, not more than 0.010% of Sb, not more than 0.005% of Pb, and the balance being Fe and inevitable impurities. The production technology comprises steps of carrying out primary steel making in an arc furnace or a converter, performing LF refining, carrying out RH / VD vacuum degassing, and performing continuous casting. The length-diameter ratio of sulfides inthe killed non-tempered steel, which is processed by the morphology control method, is not more than 8, the equivalent diameter is not more than 5 [mu]m, the cleanness of molten steel is high, T.O isnot more than 0.0012%, the grain size of the steel is not less than 7.0 grades, and the clogging rate is 0 in continuous casting.

Description

technical field [0001] The invention belongs to the technical field of metallurgy, and in particular relates to a sulfur-containing aluminum-killed non-quenched and tempered steel and a method for controlling the sulfide morphology thereof. Background technique [0002] The modern mechanical processing industry, which is developing towards automation, high speed and precision, has promoted the development of free-cutting steel, especially the rapid development of the automobile industry has driven the development of sulfur-containing and aluminum-containing free-cutting structural steel, such as non-quenched and tempered automotive gearboxes, etc. Parts are widely produced with non-quenched and tempered steel containing sulfur and aluminum. With the rapid development of my country's automobile industry, the demand for non-quenched and tempered steel is increasing. Due to its harsh environment and complex stress, non-quenched and tempered steel usually requires high contact f...

AI Technical Summary

Problems solved by technology

Among them, calcium treatment has been applied in a wide range, but after the sulfur-containing aluminum-killed non-quenched and tempered steel adopts the calcium treatment process, as the [S] content increases, the scope of the "liquid window" of the inclusions after calcium treatment decreases sharply, or even disappears. , it is very easy to store flow during continuous casting (the flow storage rate is above 50%, and the number of continuous casting furnaces is within 3 furnaces). Therefore, the production of sulfur-containing and aluminum-containing steel has always been faced with the problem of poor castability of molten steel, which affects the production rhythm , which reduces the quality of the slab and cannot meet the needs of large-scale industrial production

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