RU2063298C1 - Process of manufacture of continuous cast commercial billets from high-carbon automatic steel - Google Patents

Abstract

FIELD: metallurgy. SUBSTANCE: process is designed for manufacture of continuously cast billets for their subsequent rolling into rods. High-carbon automatic steel is melted, melt is treated in ladle with inert gas with simultaneous feed of alloying material which contains sulphur 26%, the rest being iron (ferrosulphur) into ladle. Content of manganese is ladle is brought to 1.5-2.0 per cent by mass. In this case temperature of feed of metal into crystallizer, time of blow-through in ladle and rate of drawing of ingot at definite intensity of cooling are tied up by relationship. EFFECT: increased productivity of process.

Description

 The invention relates to ferrous metallurgy, and more particularly, to continuous casting of metal, followed by the production of bar stocks from high-quality blanks.

 A known method of producing wire rod from continuously cast billets, including supplying metal from a ladle to a mold, cooling and drawing the billet from the mold and its subsequent rolling to obtain a wire rod of a given size (E. Germani. Continuous casting. M. 1961, p. 682, p. 1772 )

 The known method provides satisfactory technological characteristics when casting billets of carbon steel grades. However, when casting steel from alloyed and low alloy grades with a high sulfur content, difficulties arise, namely, the low ductility of the metal leads to the formation of longitudinal and transverse cracks in the workpieces, breakthroughs of the metal, instability of the production process, etc.

 The closest in technical essence and the achieved result is a method for the production of steel bars from continuously cast billets, including the smelting of metal, its processing in the ladle, the supply of metal to the intermediate ladle and further to the mold, the formation, cooling and drawing of the workpiece, its cutting, rolling, heat treatment , drawing, grinding and cutting of rods (E. Germani. Continuous casting. M. 1961, p. 721 722, p. 1884).

The main disadvantage of the prototype, as well as the analogue, is its low technological characteristics, with a low ductility of the metal in the temperature range T _solidus T <Mv> 800 ^o C <D>, which leads to the formation of longitudinal and transverse cracks in the ingots. In addition, in the process of machining (cutting), difficulties arise with the processing of workpieces.

The technical result of the invention is to increase the technological characteristics during the casting process, mainly increasing the ductility of the metal in the temperature range T _solidus T <Mv> 800 ^o C <D> and improving the further machinability of the workpieces to obtain the finished product.

 The technical result of the invention is achieved in that in a method for the production of bars from continuously cast billets, including the smelting of metal, its processing in the ladle, the supply of metal to the tundish and then to the mold, the formation, cooling and drawing of the ingot, its cutting into billets, rolling, heat treatment , drawing and cutting into rods and grinding during metal processing in a ladle, ferrosulfur in the amount of 75-85 kg / t is introduced into the latter and the metal is purged with inert gas from below for 2 5 minutes, and after processing in the bucket in the mold serves metal chemical composition in the following ratio of ingredients, wt.

Carbon 0.7 0.8
Silicon 0.15 0.30
Manganese 1.5 2.0
Sulfur 0.18 0.24
Phosphorus 0.04 0.08
Chrome 0.10 0.25
Nickel 0.10 0.25
Copper 0.15 0.30
Iron Else
while the metal in the mold from the intermediate ladle is fed at a temperature of 1480 1525 ^o C, the ingot is pulled at a speed of 1.2 2.0 m / min, and the surface temperature during cutting is 850 - 920 ^o C.

The presented set of essential features, namely the features of the restrictive and distinctive parts of the claims, including the input of ferrosulfur in the amount of 75 to 85 kg / t, inert gas treatment of the metal in the ladle, metal casting of a certain chemical composition and technological parameters of the ingot casting process allow casting good quality without longitudinal cracks, to conduct a stable casting process without breakthroughs of metal and to improve the workability of the metal, i.e. improve cutting conditions. This is primarily due to an increase in the ductility of steel in the temperature range T _solidus T ₈₀₀ ^o C and the transfer of low-melting iron sulfides to refractory manganese sulfides.

 A method for the production of bars from continuously cast billets is as follows.

Steel is smelted in electric arc furnaces with aluminum slag deoxidation and ferromanganese alloying, the temperature of the metal in the furnace for 3 5 minutes before release is 1640 1650 ^o C. The metal from the furnace is released into a ladle well heated by steel and in the process of discharge, ferrosulfur in the amount of 80 kg per 1 ton of metal. The metal in the ladle is blown from below through a porous plug with argon or nitrogen for 3 minutes to a temperature of 1590 1600 ^° C. The metal is fed into the mold from the intermediate ladle through an immersion nozzle. Pour metal of the following chemical composition, wt. 3 carbon 0.8; silicon 0.3; Manganese 2.0; sulfur 0.2; phosphorus 0.05; chrome 0.2; nickel 0.2; copper 0.2; iron and impurities 95.6. The temperature of the metal in the tundish during casting is 1480 1525 ^o C. Steel is poured on a continuous casting machine in billets with a cross section of 140 mm square or 160 mm square. The metal mirror in the mold is protected by a slag-forming mixture of the following composition, wt. amorphous graphite 15; silica sand 22; soda ash 7; iron oxide 3; fluorine-containing substance 20; ferrochrome slag 33.

An ingot formed in the mold is pulled at a speed of 1.7 m / min. The water flow to the mold is 1800 l / min, the water flow to the secondary cooling zone is 32 l / min. The cooling rate and the indicated drawing speed of the ingot make it possible to reach the surface temperature of the ingot in the cutting zone of about 900 ^° C. The ingots are cut into blanks of 4.3 m in length.

The workpiece is rolled in a duo-reverse stand with preliminary heating, while the workpiece is squeezed from a square of 140 mm to a rectangle of 80 x 90 mm, and then the workpiece is rolled in a continuous group of stands on an 8 mm wire rod, followed by cooling in air. Heat treatment of wire rod is carried out in a continuous roller furnace with a speed of movement of revolts of 0.9 m / min. The temperature of the gas mixture in the furnace is 760 660 ^o C. The wire rod is drawn with compression in one redistribution of 40 50%. The diameter of the finished wire is chosen with allowance for grinding. The wire is cut into bars of measured length, straightened, and then ground to a predetermined size with a given accuracy and surface quality.

 The use of the invention allows to increase the plastic properties of the metal by 50% to eliminate the formation of transverse and longitudinal cracks on the cast billets and to improve the further machinability of the metal to obtain the finished product.

Claims (1)

A method for the production of continuously cast billets from high-carbon automatic steel for the subsequent production of rods from them, including smelting metal, treating it with an inert gas in the ladle, feeding the metal into the tundish and then into the mold, forming, cooling and drawing the ingot, cutting it into billets at 850 -920 ^o C, characterized in that when processing metal in a ladle, alloying material is fed into the latter in the composition: 20% sulfur, the rest is iron, in an amount of 75-85 kg / t, the manganese content in the metal in the ladle is adjusted t up to 1.5-2.0 wt. the melt in the ladle is blown with inert gas from below for 2-5 minutes, the metal is fed into the mold at 1480-1525 ^o C and at a flow rate of water for cooling the mold 1800 l / min, the ingot is pulled at a speed of 1.2-2.0 m / min .