SU740859A1 - Melt for heating titanium and its alloys - Google Patents

Description

The invention relates to the field of metallurgy and can be used in various industries in the manufacture of hot-deformed semi-finished products, especially stampings used with an untreated surface, as well as during heat treatment with air heating of billets and parts made of titanium alloys.

Salt melts suitable for stamping parts are subject to a number of special requirements. Such melts should have a low viscosity, since salt falling onto the engraving of the stamp may prevent it from filling with metal. In this regard, the film thickness on the surface of the workpiece removed from the bath should not exceed 0.1 mm The melt should be clean, not contain solid inclusions, which, getting into the cavity of the stamp, increase the surface roughness of the stampings and reduce.

Stability of their sizes. At the same time, the importance of such requirements as the lack of interaction with the lining of the bathtub and the metal of the workpieces, stability during storage and long-term operation, the absence of toxic emissions, the deficiency of the constituent resins and their possibly lower cost.

The successful development of salt mixtures for stamping. Expands the scope of application of parts with non-machined surfaces, the structural strength of which is significantly higher and the manufacturing cost is lower than parts subjected to machining to a high class of surface cleanliness.

Known, for example, the composition [1], in which 4 are most fully taken into account all these requirements and which has the following ratio of components, wt.%:

borax 95.0-98.90, sodium hydroxide

1.1-5.0.

This liquid melt at 6001200 ° C moistens the surface well, when heated steel billets does not cause decarburization of the metal. A thin film remains on the surface of the workpieces, which provides reliable protection of hot steel blanks of various grades from contact with the atmosphere. However, when using this melt as a medium for heating titanium billets, an interaction of the salt melt with titanium is observed, accompanied by surface oxidation and the formation of a 15 gas-saturated layer.

The aim of the invention is to eliminate corrosion and oxidation of the surface of the product and reduce the degree of contamination by gases of the metal surface 20 layer. After extraction from titanium and its alloys, after extraction from the bath, a thin film should remain, which protects the metal surface from interaction with air, 25. This film should be easily separated after cooling the product without the use of special devices.

To achieve this goal, at least one alkaline oxide is added to the mixture of calcined borax and sodium hydroxide and the components are contained in the following ratio, wt.%:

Borax 94.5-99.0 ³⁵

Sodium hydroxide 0.5-1.5

At least one alkali metal oxide 0.5-4.0 ₄₀

The proposed compositions cover the surface of the heated metal thin glassy film by lowering the items in a bath of the molten composition at 1200 C without special za- ₄₅ provided protective atmosphere (in air).

The study of the metal subjected to heating in the proposed melt showed no signs of corrosion and oxidation on the surface of titanium billets ₅ θ woks, and the degree of gas contamination by the metal of the surface layer, estimated by the increase in microhardness and the depth of the layer of increased hardness, was 3-5 times less than ₅₅ Me- thallium similar heating in conventional melts.

The proposed melt does not cause destruction of masonry materials and bath electrodes; there is no evaporation and release of harmful toxic substances, which greatly expands the scope of application of the proposed composition.

The following have been received and tested ^! compositions shown in the table.

Composition The content of components, wt.% borax hydro - sodium ocean sodium oxide lithium oxide 1 98.0 1,5 0 * 5 - 2 97.5 1,5 1,0 - 3 94.5 1,5 4.0 - 4 98.9 1,0 - 0.1 5 96.0 1,0 - 3.0 6 95.0 1,0 - 4.0

Below are the values of microhardness of metal at a depth of 50 microns. ₂ Composition Myc hardness, kg / mm

1225

2290

3235

4210

5255

6285

The use of the proposed melt for heating titanium and its alloys for stamping in comparison with known melts provides the following advantages:

after removing them from the melt, a film with a thickness of up to 0.1 mm remains on the surface of heated billets, which protects the hot metal from contact with the atmosphere} the resulting film protects the titanium surface from corrosion, oxidation and sharply reduces the level of gas contamination of the metal of the surface layer;

the film is easily separated from the product without the use of additional equipment;

The proposed salt melt is distinguished by its simplicity of production, low cost and non-defiiteness of the feedstock, and suitability for long and repeated use. °

The introduction of non-oxidizing high-speed heating in the proposed salt melt of titanium alloys in the manufacture of semi-finished products · and during the heat treatment of workpieces and parts will reduce the heating time by at least 2 times, and, 'also eliminate the irreversible loss of metal from corrosion, oxidation and removal of gas-saturated layer (on average, these losses amount to 10%) and due to this ensure the economic effect of 600-1000 rubles. per 1 ton of processed metal.

Claims (1)

374 drills 95.0-98.90, sodium hydroxide 1.1-5.0. This flowable melt at 6OO12OOC. Wets the surface well, and when heating steel billets it does not cause the metal to decarburize. A thin film remains on the surface of the workpieces, which provides reliable hot-weather hot steel workpieces of various maro from contact with the atmosphere. However, when using this melt as a medium for heating the titanium blanks, the interaction of the salt melt with titanium is observed, accompanied by the oxidation of the surface and the formation of a gas-rich layer. The aim of the invention is to eliminate corrosion and oxidation of the surface of products and reduce the degree of contamination of the metal of the surface layer with gases. On the surface of titanium and its alloys, after removal from the bath, a thin metal must remain, protecting the metal surface from interaction with air. After cooling the product, the film must be easily separated without the use of special devices. To achieve this goal, a mixture of calcined borax and sodium hydroxide is added. At least one alkaline oxide is added and the components are contained in the following ratio, wt.%: Bura 94,5-99,0 Sodium hydroxide about 5-1 5 at least one oxide of alkali metal, 5-4, O The proposed compositions coat the surface of the heated metal with a thin glassy film when the part is lowered into the bath with the molten composition at 12OO C without a special protective atmosphere (air). The study of the metal subjected to heating in the proposed melt showed the absence of traces of corrosion and oxidation on the surface of titanium blanks, and the degree of contamination of the metal of the surface layer with metal gases, estimated by the increase in microhardness and depth of the layer of increased hardness, was 3-5 times less than metal with similar heating in known melts. The proposed melt does not cause the destruction of masonry materials and bath electrodes; evaporation and the release of harmful toxic substances is absent, which greatly expands the scope of application of the proposed composition. Were obtained and tested the following formulations listed in the table. The following values of microhardness of metals, ELLs and at a depth of 50 µm, CompositionMicrohardness, kg / mm 1225 2290 3235 4210 5255 6285 The use of the proposed melt for heating titanium and its alloys for stamping provides the following advantages compared to known melts; on the surface of heated billets, after the extraction from the melt, a film with a thickness of up to 0.1 mm remains, which protects the hot metal from contact with the atmosphere; the resulting film protects the titanium surface from corrosion, oxidation and drastically reduces the level of contamination by gases of the surface metal layer; the film is easily separated from the product without the use of additional equipment; The proposed salt melt is characterized by simplicity of production, low cost and non-deficiency of the raw material, suitable for long-term and repeated use. The introduction of non-oxidative high-speed heating in the proposed salt melt of titanium alloys during fabrication 2 times to reduce the duration of heating, to exclude also the irretrievable loss of metal from corrosion, oxidation and removal of gas layer (in the meantime, these losses amount to 1O%) and due to this ensure the economic effect of 60O-1OOO rubles. per 1 ton of processed metal. Claim of the Invention A melt for heating titanium and its alloys, containing borax and sodium hydroxide 9, characterized in that, with a chain for eliminating corrosion and oxidation of the surface of products and reducing the degree of contamination of the metal of the surface layer with gases, it additionally contains at least one alkaline oxide metal in the following component ratio, wt.%: Bura 94,5-99,0 Sodium hydroxide 0.5-1.5 At least one oxide alkaline, 5-4, O Sources I1 "{jurmatio taken into account when examination 1. Copyright certificate USSR number 63391O, cl. C 22 F 1/18, 1977.