SU996465A1 - Composition wire for modifying steel - Google Patents

Description

The invention relates to ferrous metallurgy, in particular to the deoxidation and modification of steel and alloys. Composite materials are known for the deacidification and modification of a steel, which is a wire or ribbon, the core of which consists of powders of active elements and their mixtures, and the shell is formed by a tape of aluminum, iron or steel 11}. The closest in technical essence and the achieved effect to the proposed is a composite of wire containing a core of powder, silicocalcium and a steel sheath, such that the core is 0, 9 of the weight of the wire. Such a material makes it possible to drastically increase the degree of assimilation of the silicon calf and the quality of the modified ones 12. The disadvantage of this material is that it does not contain slag-forming components and does not lead to fluxing and removing from the metal formed during the modification of non-metallic inclusions with cored wire, and consequently reduces the effectiveness of the modification. When processing steel with this material, it is not possible to improve the surface quality of the ingot and reduce waste during rolling. The object of the invention is to increase the modifying and transmitting ability of the material and to improve the surface quality of the ingot. . -; This goal is achieved by the fact that, according to the invention, kbmpbyun on a wire for modifying steel, squeezing a ro from nopouiiui skpvkokaltsi and stalnuk) sheath, additionally contains fluorspar and nepheline at the next component weight. %: Svlykalyschuyu-ZO Fluorspar5-1O Nephelin5 1O Steel sheathEverything. Silikalysh in this composite tracker plays the role of a steel modifier, it leads to shredding of the dendritic structure of the steel and increases the density of the macrostructure of the ingot and the workpieces. Calcium is part of non-metallic inclusions, crushes and changes their morphology and improves the distribution of inclusions in the ingot. It is advisable to introduce silicocalcium with a high content of calysus CK20 into the cored wire to modify the otali. SK25, SKZO according to GOST 4762 71. When the content of silicocalc in the wire is less than 1O%, its influence on the structure and properties of the steel is ineffective. The manufacture of cored wire with a content of silicocalcium in a composition of more than 30% is difficult due to the limited filling factor of the wire with powders. In addition, when the content of silicocalcium in the wire is higher than 30% and its consumption is more than 3 kg / ton of steel, the modification is accompanied by metal boiling and noticeable smoke emission due to evaporation of calcium, which is undesirable. Fluorspar (Sap2) nepheline (NOoO rACgO: 25i02) are intended for the formation of liquid mobile slag for the purpose of fluxing and removal of non-metallic inclusions formed by calcium modification. The resulting slag as a result of modifying the steel with powder wire lubricates the walls of the mold or mold of continuous casting machines, reduces the thermal stresses in the ingot crust and improves its surface quality. and improving the quality of the ingot surface is hardly noticeable, when its content in the wire is higher than 10%, the melting temperature and temperature can be reduced to less than 100%, and kzhe increases gassed environment due vscheleni fluorine. Nepheline is also incorporated into the composition to form a liquid slurry slag and increase its refining ability. In addition, nepheline significantly increases the strength of the mixture, which is very important when forming cored wire. When the content of nepheline in the wire is less than 5% of its content on the properties of slag is small. The introduction of nepheline into the cored wire in an amount of more than 10% is undesirable, since in this case the melting point of the slag rises and because of the presence in its composition of a large amount of Aco2o oxide. The steel sheath of the wire, on the one hand, plays the role of a container for a powder mixture of silicocalcium, fluorspar and nepheline, on the other hand, the steel sheath, when melted in steel, plays the role of microcoolers, reduces steel overheating, and thereby increases the efficiency of modification. To form the sheath of flux-cored wire for modifying steel and alloys, use a 0.2-O, 5-mm-thick tape made of steel 10, 08KP, etc. With a smaller thickness, the tape makes it difficult to form the wire due to a possible ribbon break. greater than 0.5 mm, the filling factor of the wire is reduced. Example. Pilot batches of powder wire for steel modification were made, the composition of which is given in Table. 1. Silicocalcium, fluorspar, nepheline are crushed on a shear crusher, then ground in ball mills, sieved through a 1x1 mm mesh sieve, and after mixing the components in a mixer, the mixture is fed to a wire mill to form cored wire. To form the shell, a strip of steel 08KP 0.5 mm thick is used. Powder wire is formed with a diameter of 4.5 mm. The powder wire produced in this way is used to modify 17GS steel. Steel 17GS is melted in a MGGIO2 furnace. Melting weight 16O kg. After preliminary deoxidation and doping with silicon and manganese and final deoxidation in the furnace, alc. With a mini and titanium steel is poured into 4 kg of the mold, where the cored wire at the rate of 2 kg / t of steel is introduced beforehand. The chemical composition of steel 17GS, weight. %: carbon O, 18; silicon O, 54; manganese 1.22; sulfur 0, O23; phosphorus O, O20; titanium O, 02; aluminum O, 02. From the central zone of the ingots they cut out longitudinal and pop-side templates to control the macrostructure and dendritic structure, as well as the preparation of samples for metallographic analysis and

test mechanical properties. Billets for testing mechanical properties are normalized at 930 ° C. The content of non-metallic inclusions in steel is determined in indices by the method L in accordance with GOST 1778-7О.,

The results of determination of the content of non-metallic inclusions and mechanical properties are given in Table. 2

Studies show that in steel ingots modified by the proposed flux-cored wire, the macrostructure is more dense and the dendritic structure is more dispersed compared to an ingot of steel treated with a prototype powder, the content of nonmetallic inclusions is 1.5–2 times lower, with approximately equal strength

plasticity is 15–2% higher, and impact viscosity at room temperature is 15–30% higher and 30–30% higher at negative temperatures.

Tested - flux-cored wire for modifying the steel of compositions M "2 (Table 1) when casting 13-tonne sheet ingots of 17GS steel. Test show that the surface quality of the buggy

modified steel than ordinary steel; yield of sheets 1.5-2% higher compared with conventional technology. gia. In addition, the amount of slab stripping is reduced by ZO-40%.

The expected economic effect from the application of the proposed powder composite wire for steel modification is at least 1 rub. per 1 ton of steel.

Table 1

four

5.5. ICr (Prototype)

53.2 4O, 7

Claims (1)

Invention Formula Composite wire for modifying steel, containing a core of silicocalcium powder and a steel sheath, is different in that, in order to increase the modifying Table 2 22.4 51.2 9.8 4.2 and capacity relieving, material. and improve the quality of the ingot surface, the core contains fusible spar into nepheline in the following ratio of components, wt ..%:. Silikalyshy10-30 Fine spar5-1O 7996465 Nephelin5-1O, 1. Steel sheathOalgalkl, C Sources of information, 2. taken into account during examination. C 8 Japanese Application No. 54-35110, 21 C 7 / OO, published. 1979. Japanese Application No. 51-40852, 21 C 7/00, published. 1976.