SU1647027A1 - Method for production of low- and medium-carbon pipe steel - Google Patents

Abstract

This invention relates to ferrous metallurgy, in particular to methods for the deoxidation and casting of carbon pipe steels. The purpose of the invention is to improve the quality of steel. For this, during steelmaking, the period of pure boiling is continued for 50–60 min, deoxidation is started by introducing aluminum into the ladle followed by sitting down of other necessary deoxidizing agents and alloying additives with the mandatory presence of titanium and calcium in the ratio AI: Ti: Ca Ј 5: 5: 2.5. Siphon casting is carried out at a speed of 13-20 cm / min with overheating above the liquidus line at 90-115 ° C or at a speed of 30-40 cm / min with overheating at 1250-150 ° C. The use of technology allows to reduce the flaws in the flaws, increases the output of pipes of grade 1. 3 dw., 3 tab.

Description

This invention relates to metallurgy, in particular to smelting, deoxidation and casting (in ingots) of steel.

The purpose of the invention is to improve the quality of the metal.

FIG. 1-3 shows graphs characterizing the method.

The state of the metal before deoxidation is mainly determined by the general chemical composition and temperature of the metal. The condition of the metal before deoxidation, in terms of the content and distribution of oxides and other non-metallic inclusions, is almost uncontrollable, so degassing the bath with a clean kilogram for 50-60 minutes is a necessary process for obtaining high-quality metal. With a shorter or longer duration of this process, the quality of the metal deteriorates (Fig. 1).

To control the crystallization process, the following order is used: if possible, the metal is released without preliminary deoxidation, deoxidation begins by sitting all the necessary amount of aluminum in the ladle. Under the influence of a metal jet, aluminum of any size melts, resulting in a deoxidation effect with liquid aluminum. The subsequent simultaneous sitting of all deoxidizers and modifiers promotes their use as intended.

The proposed ratio of aluminum, titanium, and calcium provides the best structure of the ingot and, as a result, an increase in the yield of good metal and first grade (Fig. 2). Bauman prints of two grades of steel 36G2S and 40GT are obtained: the first is liquefied by the existing technology, and the second by the proposed one. The latter is characterized by the best structure of the ingot (content of

VI VI O Yu sj

the sulfur content became the same). From FIG. 2, it can be seen that the melting of steel 40 GT with the yield of second grades of 3.5% is more common, and on 36G2S steel the maximum frequency is 5.5%. In addition, the steel modified by the proposed technology is characterized by improved processability (rollability, machining and DF-) The temperature of the liquid metal prior to release into the ladle is an adjustable factor. For siphon casting, two temperature zones of overheating of the liquid metal are established above the liquidus line: high - 120-150 ° C and low - 90-115 ° C. Of these, the lower (90-100 ° C) and upper (140-150 ° C) limits of the metal overheating above the liquidus line are optimal (Fig. 3). The corresponding casting speeds are also selected: 30-40 and 13-20 cm / min, respectively. The results of industrial experiments are explained as follows: when casting a hot (DF 120-150 ° C) metal at high speed, the casting is simulated from above, in this case the crust does not have time to form, and during casting the metal overheated by 90-115 ° C at a speed of 13–20 cm / min, a crust is created that withstands the loads (artificial reinforcement and casting are artificially created).

Laboratory and industrial experiments show that the failure of billet billets (f 180 mm) obtained from soft steel grades is noticeably improved when the content of aluminum and titanium is at the upper level: AI 0.03-0.05%, TI 0.030, 045 % At the same time, the viscous fracture becomes semi-brittle, the ar decreases.

Example. The steel smelting is carried out in an open-hearth furnace with a cage of 200 tons: filling,

melting, periods of ore and net boiling with a duration of net boiling of 55 min. With the start of production of the metal, 90 kg of aluminum are placed in the ladle, after which 300 kg of 30% ferrotitanium are planted.

and 238 kg of 20% silicocalcium. After the end of the production, the siphon casting is conducted at a speed of 17 cm / min, and the metal is overheated above the liquidus temperature and is 102 ° C (1605 ° C).

The results of industrial tests are presented in Table. 1-3.

Claims (1)

The flaw marriage is reduced by 15%, the yield of I grade pipes increases by 5%. Invention Formula The method of production of low and medium carbon pipe steel mainly in a 200-ton open-hearth furnace, including filling, melting, periods of ore and pure boiling, melt production, input into the ladle of aluminum and ferroalloys containing titanium and calcium, siphon casting, characterized by that, in order to improve quality, the duration of the period of pure boiling support equal to 50-60 minutes, and aluminum is introduced into bucket simultaneously with the start of release smelting, after which ferroalloys are introduced at with respect to aluminum, titanium and calcium, equal to 5: 5: 2.5, while casting lead with speed of 13-20 cm / min with overheating above the liquidus line at 95-115 ° С or at a speed of 30-40 cm / min with overheating 120-150 ° С. em -WITH. j o NJ J ABOUT) -WITH j o go j S 20 30 40 50 60 70 80 90 Duration of a clean bale, min. 1