SU724579A1 - Method of deoxidizing steel and alloys - Google Patents

Description

 ., 1 The invention relates to ferrous metallurgy, in particular, to the steelmaking and foundry industry. Methods are known for the deoxidation and modification of steel and alloys, including aluminum deoxidation and calcium and rare earth metals (REM) 1 and 2 modification. The closest in technical essence and the achieved result to the invention is a method of modifying steel and alloys, such as after metal deoxidation with aluminum, 0.05-0.3% calcium, 0.050, 4% zirconium and 0, O2-O, 3% REM, and after the metal is removed from the furnace, the amount of the remaining calcium in the metal. 0.02-0.2% by weight of the melt {. However, in steel modified by such methods, brittle calcium aluminates inevitably are present in large quantities, which have a negative effect on the properties of steels, especially BbicoKoiip04 if.ix, According to the known method of deoxidation and modification, steel is not deep enough. from harmful at 1s (oxygen, sulfur) and non-metallic inclusions due to the absence of sclac to absorb inclusions. In addition, when used for the modification of calcium metal, it quickly evaporates and burns out 4atfTO with metal splashes; when calcium is used in the form of silicocalcium, even at an average consumption, the majority of structural steels leave the brand composition for cream, which limits the use of the method only for high-silicon. The aim of the invention is to improve the deoxidation and refining of steel and alloys from non-metallic inclusions. The goal is achieved: STE steel is finally deoxidized with Alkminium dross in the amount of 1-3 kg / t and modified silicocalcys IHU between IKU and SILK metal in the amount of 1-3 kg / t and 1.5 kg / Accordingly, Steel, aluminum deoxidation, not inevitably contains high-alumina non-metallic inclusions, the most harmful of which is corundum, Alumina and corundum have a negative effect on the performance properties of structural and high-strength steels, as well as the polishability of stainless steels. The principal difference between the deoxidation method, aluminum, and aluminum is that aluminum is introduced into steel in the form of aluminum dross, aluminum alloy production wastes containing 50–80%, aluminum metal and slag-forming components — the rest. Slag-forming substances are melted at a temperature of liquid steel and form a liquid slag. When steel is deoxidized with aluminum dross, the formed high alumina inclusions and corundum are assimilated by the liquid slag formed at this moment from the dross slag forming substances, coagulated and removed from the metal. The upper and lower limits for the introduction of dross into steel are determined by the necessary amount of residual aluminum in the steel. When the dross is less than 1 kg / t, the steel is not sufficiently deoxidized, which leads to an increased loss of modifiers (silicocalcium and silico-metal) and a decrease in the efficiency of modification. The addition of Dross to steel in an amount of more than 3 kg / t also leads to deterioration of the properties of the increased residual content of w aluminum and its secondary oxidation when casting steel, and the surface quality of the ingots also deteriorates, which means additional waste during rolling Th eGyoYyo ore-production capacity Silicocallium together with silico-metal are effective steel modifiers. They increase the dispersion of the dendritic structure, mind hedgehog heterogeneity, crush the micrograin, contribute to the formation of small, evenly distributed 1x n nonmetallic steel structure, t, e, and are modifiers of the composition and morphology of nonmetallic inclusions. With the separate use of oylcoccalca and silico-yishmatall, the worst results are obtained, which, given their joint introduction, became the last case, the active elements such as calcium and rare-earth metals were used more efficiently. solid composition and form, the temperature of solidification of sulphides increases and the sulphide films are almost completely eliminated by eutectic the second type; the main type of inclusions are globular oxysulfides - oxides, in sulphide, the introduction of silicocalcium in an amount of less than 1 kg / t changes little the dendritic structure, the composition and distribution of inclusions in steel; with the addition of more than 3 kg / t, relatively large globular inclusions of a new type are formed. Such inclusions have a negative effect on the contact endurance and performance properties of some high-strength steels, such as ball, rail, structural. The best results are obtained when using silicocalcium with a low calcium content of the grades SK10, SK1B, Silikomishmetall, modifies the primary structure of steel, fundamentally changes the nature and distribution of nonmetallic inclusions, retards the growth of austenitic grain at high temperatures. With the introduction of siliceous metal in an amount of less than 1.5 kg / t, it has a minor effect on the dendritic structure, microstructure and properties of steel. the macrostructure, and also the stability of the mechanical properties of the steel, and also leads to an increase in the area of stripping the workpieces during the redistribution of ingots. The best structure and properties of the steel are achieved by modifying the steel by strong calcification together with silico-metal in the ratio of 1: 1. Testing of the method of liquefying and modifying the steel is carried out. The deoxidation of steel is carried out in an O, 6% manganese and O, 2% silicon furnaces. According to a known method, O, 1% aluminum and 0.1% calcium (5 kg / t silicocalcium C22 O) are introduced into the furnace, and

With the release of 0.2% zirconium, 0.15% of rare-earth metals in the form of mischmetall and 0.1% calcium (5 kg / t SC20), using this method, various amounts of aluminum dross are placed in the furnace, and in the silicocalcium CK1O together with sklikomishmetmetallom Stsimish -five. As aluminum dross, slag from aluminum-magnesium alloys of the following composition is used,%; metal part 75.82, O including Mg2.56, Ml 0.25, Fe 0, ZO, Au the rest, non-metallic (slag / va) part 24.15, including A. p, 4.76, Mgp 9.49, Fe2p50.36, MgO 0.11, MgCCj; 2.10, KCG. 5, O8, NaCfi-1.41, 5) Oa. + FO, 72, Clio 0.12, ZhO 0, O09. The composition of SceMish-3 is as follows,%: REM 23.2 St35.2, Ai 3.8, Ca 2.3

; Mg 0.96, Rei impurities - the rest. From steel treated in this way (ingots of 50 kg each are cast from 4OX. From the ingots of the 6t cutout, the longitudinal template of the radiation of the macro and dendritic structure, as well as blanks to control the microstructure, determine the content of non-metallic inclusions according to the method L in accordance with GOST 1778-70 5 C of mechanical properties. The mechanical properties of steel are determined in a cast joint after the normalization of the workpieces during and tempering at, Table 1 shows the options for deoxidation and modifying, the contents of oxygen and sulfur in sphaly and its pollution in The index of non-metallic inclusions Table 2 -. Mechanical properties of steel produced, Table 1

Famous

APkg / t SK20 1 b kg / t

Proposed

Tests show that deoxidizing and modifying steel reduces the oxygen content by 30-50%, sulfur by 10-25% and reduces the pollution index by nonmetallic inclusions by 2-3 times, increases the dispersion of the dendritic structure and improves the macro b

0, ОО56О, О22 11.3-10

table 2

Claims (2)

structure, compared with the known method. As a result, there is a significant improvement in mechanical properties: with greater strength by 2-4 Krc / Mtx, the ductility of the 4 OHL steel increases by 2 ~ 40%, and the impact viscosity by 1.5 - 2 times at room temperature and by 2-3 times at negative. temperatures. This method is applicable for deoxidation and modification of carbon alloyed and stainless steels and alloys. The method allows the use of WASTES of aluminum alloys, which are 8-10 times cheaper; the cost of aluminum used for deoxidation. On the basis of experimental data, the economic effect on 17GS was made by reducing rejects by 1.5–2 times and saving aluminin according to preliminary calculations of TECHTHT 220-300 thousand rubles1 Fig. 6 formula for the method of deoxidation and modification of steel and alloys by means of B1 alloy lines 5,798 , calcium and rare earth metal: SE, characterized in that, in order to improve deoxidation of the metal and to refine the metal from non-metallic inclusions, the final deoxidation of the steel is made of aluminum dross in the amount of 1-3 kg / t, and modifying silicocalcium together with silicomechmetall, respectively, in a quantity of 1-3 Kt / t and 1.5–3 kg / t. Information sources taken into account during the examination 1. E. Kalinnikov. Cold-resistant low-alloyed steel. Moscow, Metal15lurgi, 1976, p. 81-98. 2. USSR author's certificate N9 456492, cl. C 21 S 7/00, 1975. c. USSR author's certificate N 423852, cl. C 21 C 7/00, 1974.