SU944759A1 - Metal continuous casting method - Google Patents

Description

1 The invention relates to metallurgy, more specifically to continuous casting of metals, and is intended for use in the continuous casting of steel into large-section ingots in a vertical type plant. A known method of continuous metal casting involves feeding the metal into the mold, cooling and drawing an ingot with a decrease in the ingot drawing rate at the end of casting by 50 and drawing at this speed for a time equal to 0.3-0.5 times the solidification of the ingot. Cl J. The disadvantage of this method is that, if it is used, a significant amount of technological waste. This is explained by the fact that the application of this method allows only a slight decrease in the depth of the liquid metal well by the end of the casting. In addition, in the ingots obtained by this method, surface defects (subcortical blisters, twists, transverse folds-junctions) are formed at the end of casting due to intensive cooling of the metal meniscus in the crystallizer, as well as an increase in the content of nonmetallic inclusions due to the need to burn the canal bucket due to its tightening at low metal consumption. The aim of the invention is to increase the yield of metal by reducing the height of the shrinkage shell while maintaining the surface quality of the ingot. In order to achieve this goal, in the method of continuous metal casting, which involves feeding the metal into the mold, cooling and drawing the ingot with a decrease in the drawing rate of the ingot at the end of the casting process, for a time equal to 5 times the complete hardening of the ingot, the drawing speed of the ingot is reduced by 20 - “Oh. Pulling the ingot at the end of the casting at a reduced time of 1.0–1.5 times the full cure of the ingot at a speed of dark tempered time results in a shallower depth of the liquid metal. This prevents the formation of ingots at the end of the casting of surface defects — subcortical blisters, twists, transverse folds, and no increase in nonmetallic inclusions due to the exclusion of burning the glass of the pouring ladle is not observed. The proposed method was tested for continuous casting of carbon and alloyed steel grades St 3 20, k5, 20Х, itOX,, 65Г, etc. on a continuous casting plant of vertical type steel into molds with a section of 175x1020 mm. The smelting mass was 60–70 tons. The working speed was 0.5–0.7 m / min. The full hardening time of the ingot of the indicated cross section was 12 min. According to the calculated and experimental data. In accordance with the proposed sp. The last portions of the metal — 7–10 tons — were poured over for 12–18 minutes at an ingot drawing rate of 0, O, “B m / min. 94 After casting and cooling the ingot, the height of the shrinkage shell was determined by known methods. In tab. T and 2 show the results of testing a known method (No. 1-2), a method in which the magnitude of a decrease in the rate of ingot extrusion at the end of casting and the ratio of the duration of a decrease in the rate of extrusion at the end of casting to the time of complete solidification of the ingot out to t beyond the limits provided by the proposed method () and the proposed method (No. 3,7,8,9). The tables show that when using the proposed method (No. 8.9) the depth of the hole of the liquid metal and the height of the shrinkage shell of the ingots is less than that of the ingots obtained using known methods (No. 1 and 2), as well as the methods of casting metal which was carried out when the ingot extrusion speed and its duration at the end of casting went beyond the proposed limits (no. i | -6). The experiments also showed that the application of the proposed method will reduce the amount of technological waste from the end part of the ingot from 0, -0.7% to 0.1-0.21 and thereby increase the yield of metal. la to 99.8-99.9%.

2

50-70

0.3-0.5 23 3, 65G 1.5-1.7

Table 1

3,45,20Х, 40Х, 65Г

1.-910370

2.0.9-1.3 605320

Continued table. I

table 2

0,, 0

Not

Not

Screws On the surface - O.t-O, crusts on the side of the ingots of all

Claims (1)

1. Typical technological instructions for continuous casting of steel. M., Minchermet USSR, 1976, p. 130.