RU-2861499-C1 - METHOD FOR PRODUCING “20ДХЛ” STEEL BY ALUMINOTHERMY

Abstract

FIELD: metallurgy; foundry production. SUBSTANCE: invention relates to aluminothermic methods for smelting a ferro-carbon alloy corresponding in chemical composition to steel “20ДХЛ”, used for the production of critical loaded parts. The method includes preparing a thermite charge containing mill scale, a reducing agent in the form of aluminium powder, ferromanganese, ferrochromium, loading the thermite mixture into a crucible, carrying out an exothermic reaction with the formation of a melt. Aluminium alloy powder “ВД17” is used as the reducing agent, with the following ratio of components of the thermite charge, mas.%: mill scale 74.68-76.92, “ВД17” aluminium alloy powder 20.37-22.39, ferromanganese grade “ФМн78(A)” 1.66-1.84, ferrochromium grade “ФХ025A” 0.97-1.16. EFFECT: obtaining steel “20ДХЛ” with high mechanical properties by the aluminothermic method. 1 cl

Inventors

• KOMAROV OLEG NIKOLAEVICH
• POPOV ARTEM VLADIMIROVICH
• Khudiakova Vilena Aleksandrovna
• Zhilin Sergei Gennadevich
• Predein Valerii Viktorovich

Dates

Publication Date

20260505

Application Date

20251127

Claims (9)

1. A method for producing 20DHL steel by aluminothermy, including the preparation of a thermite charge containing metallurgical scale, a reducing agent in the form of aluminum powder, ferromanganese, ferrochrome, loading the thermite mixture into a crucible, carrying out an exothermic reaction to form a melt, characterized in that aluminum alloy powder VD17 is used as the reducing agent, with the following ratio of thermite charge components, wt.%:
2. Metallurgical scale 74.68-76.92,
3. including, wt.%: C 0.150; Mn 1.188; Si 2.960; S 0.030; P 0.030; Fe 71.500; Al 0.697; Ni 0.188; Cr 0.173; Cu 0.444; O2 22.639; impurities the rest;
4. Aluminum alloy powder VD17 20.37-22.39,
5. including, wt.%: Al 93.41; Mn 0.59; Si up to 0.3; Ti up to 0.1; Cu 2.95; Fe 0.3; Mg 2.25; Zn up to 0.1;
6. Ferromanganese grade FMn78(A) 1.66-1.84,
7. including, wt.%: Mn 78.050; C 6.990; Si 0.790; S 0.008; P 0.500; Fe the rest;
8. Ferrochrome grade FH025A 0.97-1.16,
9. including, wt.%: Cr 79.500; C 0.110; Si 1.830; S 0.028; P 0.030; Fe the rest.

Description

The invention relates to the fields of metallurgy and foundry production, namely to methods for smelting an iron-carbon alloy corresponding in chemical composition to 20DHL steel(GOST 977-88), used for the production of critical loaded parts that require high strength and sufficient toughness, operating under static and dynamic loads in various industries. A method for producing 20DHL steel by aluminothermy is known, described in the abstract of the dissertation for the degree of candidate of technical sciences by V.V. Predein's "Control of the Structure and Properties of Steel Castings from Thermite Materials by Aluminothermy", adopted by the applicant as a prototype (see https://sovet.knastu.ru/media/files/_bdka4H.pdf), which presents an alternative method for producing 20DHL steel, differing from traditional methods using external energy sources in that the melt of the required chemical composition is obtained by aluminothermy, using the heat of an exothermic reaction occurring in special thermite mixtures, the main components of which are a complex of iron oxides (metallurgical scale - see Iron scale, Table 1, p. 9 of the above-mentioned abstract) and a reducing agent (aluminum alloy powder - see Reducing Agent No. 2, Table 1, p. 9 of the above-mentioned abstract), various fillers, ferroalloys, ligatures, etc. are introduced to control the chemical composition. On page 14 of the above-mentioned abstract, a specific composition is given that, if the conditions described in the abstract are met, allows ultimately to obtain a melt corresponding to the chemical composition of 20DHL steel, in wt. %: iron scale - 74.75; reducing agent - 22.33; ferromanganese grade FMn78(A) - 1.75; ferrochrome grade FKh025A - 0.97; copper grade M1 - 0.2%. In this case, the scale has the following chemical composition, in wt. %: C 0.150; Mn 1.188; Si 2.960; S 0.030; P 0.030; Fe 71.500; Al 0.697; Ni 0.188; Cr 0.173; Cu 0.444; O 2 22.639. And the reducing agent has the following chemical composition, wt. %: Al 89.443; Mn 0.304; Si 1.097; Cr 0.062; Ni 0.008; Cu 2.040; Fe 0.166; Mg 3.917; Zn 2.961. The disadvantage of this method is the use of fairly large particles of M1 grade copper to bring the chemical composition of the steel to the requirements of regulatory documentation, wt. %: C 0.15-0.25; Mn 0.5-0.8; Si 0.2-0.4; S up to 0.040; P up to 0.040; Cr 0.8-1.1; Cu 1.4-1.6, which are quite difficult to dissolve during the fast exothermic process of steel production, which does not guarantee a uniform distribution of copper in the volume of the casting, while areas of zonal liquation of this element are formed. Furthermore, the use of an aluminum alloy with a high impurity content and a reduced active aluminum content as a reducing agent necessitates the formation of thermite compositions with a higher reducing agent content. This affects the ratio of the resulting reaction products. Specifically, the yield of the metallic phase is reduced, as well as the thermal effect of the reaction, which leads to a reduction in the alloy's liquid state time, which is insufficient for the melt to settle and effectively remove non-metallic inclusions and transform them into the slag phase. The factors described above influence the uniformity of the steel structure and the predicted properties of the steel. The objective of the claimed invention is to obtain, by the aluminothermic method, 20DHL steel with high mechanical properties comparable to the characteristics of similar steel obtained by traditional smelting technology and subsequent heat treatment. The technical result of the claimed invention is that the claimed method makes it possible to obtain 20DHL steel with high mechanical properties, which are comparable to the characteristics of similar steel obtained using traditional technology, using the aluminothermic method. The stated problem is solved due to the fact that in the method of producing 20DHL steel by aluminothermy, which includes the preparation of a thermite mixture containing metallurgical scale, a reducing agent in the form of aluminum powder, ferromanganese, ferrochrome, loading the thermite mixture into a crucible, carrying out an exothermic reaction with the formation of a melt, the following differences are provided: aluminum alloy powder VD17 is used as a reducing agent, and the components of the thermite mixture contain, by weight %: Metallurgical scale 74.68-76.92 Aluminum alloy powder VD17 20.37-22.39 Ferromanganese grade FMn78(A) 1.66-1.84 Ferrochrome grade FH025A 0.97-1.16, including, wt. %: Cr 79.500; C 0.110; Si 1.830; S 0.028; P 0.030; Fe the rest. The scale has the following chemical composition: wt. %: C 0.150; Mn 1.188; Si 2.960; S 0.030; P 0.030; Fe 71.500; Al 0.697; Ni 0.188; Cr 0.173; Cu 0.444; O2 22.639; impurities the rest. Powdered aluminum alloy VD17 has the following chemical composition: wt. %: Al 93.41; Mn 0.59; Si up to 0.3; Ti up to 0.1; Cu 2.95; Fe 0.3; Mg 2.25; Zn up to 0.1. Ferromanganese grade