SU1534094A1 - Method of enhancing the strength of articles of titanium alloys - Google Patents

Abstract

The invention relates to methods for machining parts from titanium alloys and can be used in the engineering, aviation and other industries. The aim of the invention is to intensify the saturation process and simplify the process while maintaining the quality of the hardened layer. A product of technical copper with a thickness of 100-190 µm is applied to the product made of titanium alloys, which is pressed against the surface of the part with a pressure of 10-100 MPa, complete or local heating is carried out in a normal atmosphere to a temperature of 0.9 ... 0.94 polymorphic transformation temperature alloy and incubated for a period of 1 min per 1 mm maximum thickness of the product. This allows the process to be intensified 1.3-2.4 times, as well as to simplify the technology while maintaining the quality of the hardened layer. 2 tab.

Description

The invention relates to methods for treating products from titanium alloys and can be used in the engineering, aviation and other industries.

The aim of the invention is to intensify the saturation process, as well as to simplify the process while maintaining the quality of the hardened layer.

As a foil, technical copper with a thickness of 100-190 µm is used, which is pressed against the surface of the part with a pressure of 10-100 MPa, full or local heating of the part in an air atmosphere to a temperature of 0.9-0.94 of the polymorphic transformation of the alloy is carried out and held for time of min per 1 mm maximum thickness of the product.

The method allows the surface of large-sized parts or their individual parts to be hardened using local heating, for example, high-frequency currents (HDTV), gas-flame, etc.

The proposed solution makes it possible to exclude an expensive vacuum furnace from the process, significantly reduce the material costs associated with the process of diffusion saturation in a vacuum, and reduce the total process time. The use of technical copper eliminates the need for special manufacture of amorphous films, which greatly simplifies the process technology. In addition, the purity of technical copper (99.9-99.5% C) imposes a limit on

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the content of harmful impurities: bismuth (0.001-0.003%) and lead (0.005-0.05%), causing red brittleness, which causes technological difficulties. The foil from technical copper, having a crystal structure, is plastic.

Example 1. Technical copper saturation 3 (99.5% Cu) of titanium alloy samples with mm cross section is carried out. Purified from oxide films and defatted copper foil (thickness 120 μm) and the sample is pressed tightly with a pressure of 50 MPa. The samples are heated and kept in an electric furnace with an air atmosphere at 940 ± 10 ° С, the holding time of the heated samples is 0.5; one ; 1, 5 and 3 min. Per 1 mm of the sample thickness, followed by air cooling.

The test results are given in table.1.

The research results shown in Table 1 show that the exposure time, taken less than 10 minutes, does not allow for the required thickness of the diffusion layer. In addition, experiments have established that a holding time of 1 minute per 1 mm of sample thickness is minimal, during which the necessary conditions for the heat treatment of the alloy are provided.

The use of an exposure of more than 10 minutes leads to an unreasonable increase in time and material costs, with a slight increase in the thickness of the diffusion layer, which causes a decrease in the efficiency of the diffusion saturation process.

PRI mme R 2. Technical copper is saturated with a sample of a titanium alloy with a cross section of mm. Foil 0.19 mm thick is used. The surfaces of the copper foil and the sample are mechanically cleaned of the oxide film. Then the copper foil is applied to the sample, which is fixed in a fixed contact, connected to one of the terminals of the power transformer. Another terminal of the power transformer is connected to a movable contact, which is used to tightly press the copper foil to the sample, providing a pressure in the range of 10-100 MPa. Heating at the point of contact of the copper foil with the surface

the sample is made before passing a current of 3000 A, while the movable and fixed contacts are made of copper; they have channels through which water is passed to remove the heat generated by the passage of current at the points of contact with the foil and the sample. A holding time of 2 minutes is determined experimentally and is optimal for this case.

Measurements of hardness over the depth of the diffusion layer show that the saturation of titanium alloys with copper according to the proposed method makes it possible to obtain layers with a thickness of more than 0.8 mm, which, compared with the known (0.3 mm, exceeds the depth of the diffusion layer by two or more times. that in the proposed method the saturation of the surface is carried out only with copper, measurements of hardness on the surface of the hardened layer show quite comparable values of hardness with hardness obtained in a known method with complex saturation (Table 2).

In addition, with an increase in cooling rate, an increase in mechanical properties occurs. For example, samples cooled in water (HRC 40) show an increase in core hardness of 7 units ”compared to the hardness of samples cooled with a furnace (HRC 33). The tensile strength of the core increases by 450 MPa, and relatively high plasticity indices (c 10%) are maintained.

Thus, the application of the proposed method allows to intensify the saturation process by 1.3-2.4 times, as well as to simplify the technology while maintaining the quality of the hardened layer.

invention formula

The method of hardening parts made of titanium alloys, including the imposition on the surface of a part of metal foil, their heating, holding and cooling, characterized in that, in order to intensify the saturation process and simplify the method while maintaining the quality of the hardened layer, technical copper is used as a foil. 190 microns

hoses with a pressure of 10-100 MPa, heating is carried out in an air atmosphere to a temperature of 0.9-0.94

the shutter speed is for a period of 1 minute per I mm of maximum product thickness.

Table 1

10 15 30

10 490-510 525-530 550-560

Table 2

Indicators by the way

known to the proposed Nomu when the thickness of the foil, microns

100 | 120 G190

300 350 500 820

1170 1070 1070 1070 400 420 580 650

Claims (1)

Claim A method of hardening parts made of titanium alloys, including applying a metal foil to the surface of the part, heating, holding and cooling, characterized in that, in order to intensify the saturation process and simplify the method while maintaining the quality of the hardened layer, technical copper 100 is used as a foil -190 μm, 1534094 * of the polymorphic transformation of the alloy, and the exposure for a time of 1 minute per 1 mm of the maximum thickness of the product. Table 1, which is pressed against the surface of the part with a pressure of 10-100 MPa, is heated in an air atmosphere to a temperature of 0.9-0.94 The exposure time of the sample with a cross section of 10 * 10 mm, min 5 10 fifteen thirty The thickness of the diffusion layer, microns 285-310 490-510 525-530 550-560 Table 2 Method Parameters The indicators for the method - known for the proposed foil thickness, microns ----------- 190 100 .20 The thickness of the diffusion layer, microns 300 350 500 820 Hardness HV _OOS J on the surface 1170 1070 1070 1070 at a layer depth of 300 microns 400 420 580 650 g