RU2639751C1 - METHOD FOR HEAT TREATMENT OF SHEETS OF Mn-Cu SYSTEM ALLOYS - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: method for heat treatment of sheets of Mn-Cu system alloys for restoring their damping capacity includes heating at the temperature 150-400 °C, holding at least 525 s per 1 mm of sheet thickness and cooling at a rate at least 2 °C/s.

EFFECT: increased recovery efficiency of Mn-Cu alloys with Mn content 36-80 percent after holding or deformation.

3 tbl, 3 ex

Description

The present invention relates to the field of metallurgy, namely the heat treatment of structural damping alloys of the Mn-Cu system, which allows to restore the functional properties (damping ability) of these alloys after plastic deformation and aging.

A known analogue method of restoring the damping ability of an alloy G75D25 (Alloys of the Mn-Cu system. Structure and properties: Monograph / Udovenko V.A., Markova G.V., Rostovtsev R.N. - Tula: Grif and K, 2005. - 152 C.), including heating to a temperature of 400 K (~ 127 ° C) and holding for one hour, at which there is a complete restoration of damping ability.

The disadvantage of this method is that heating to a holding temperature of 400 K (~ 127 ° C) was carried out under laboratory conditions and a complete restoration of the damping ability was recorded only for an alloy of the specified composition.

The closest in technical essence compared with the proposed method is a method of restoring the physicomechanical properties of metal (Pat. RF 2084544, IPC ⁸ C21D 1/78 Method of restoring physicomechanical properties of metal in a reactor vessel. Publ. 20.07.1997), which consists in heating metal at a temperature T _n = (0.3-0.4) T _pl , where T _pl is the melting temperature of the reduced metal, holding at this temperature, sufficient for the diffusion of impurity elements, and additional creation using thermal radiation electric heaters and cooling air of temperature field gradients moving throughout the metal volume — the directed movement of impurities over the metal volume until the local concentrations of impurities decrease, their averaging over the volume of the reduced metal to acceptable values, and create compression zones through which electric current is passed.

The disadvantage of the prototype method is the complexity and complexity of the implementation due to the need to use additional devices that could ensure the creation of temperature field gradients by volume of the metal and direct transmission of electric current.

The technical result of the invention is to reduce the complexity and accelerate the method of restoring a high level of functional properties of products or parts from Mn-Cu alloys after plastic deformation and / or long-term storage.

The specified technical result is achieved due to the fact that the method of heat treatment of sheets of alloys of the Mn-Cu system includes restoring the damping ability of the sheets by heating, aging and cooling, and restoring the damping ability of the sheets is carried out by heating at a temperature of 150 ÷ 400 ° C, exposure not less than 525 s per 1 mm of sheet thickness and cooling is carried out at a rate of at least 2 ° C / s.

The claimed method was repeatedly tested in laboratory conditions of Tula State University. At the Department of Physics of Metals and Materials Science of Tula State University since the 1980s. work is underway to study high damping alloys, in particular alloys of the Mn-Cu system. The results of these studies indicate the possibility of obtaining high damping ability in alloys with a manganese content of 36 ... 80%.

Below the invention is illustrated by examples, not limiting its scope.

Examples

Recovery of functional properties after aging

A sheet 5 mm thick of alloy G75D25 (of the following chemical composition: Mn 73.7%; Cu 25%; Fe 0.8%; S 0.25%; P 0.25%; total impurity content 1.3%) was thermally processed according to the optimal mode, which consists in hardening from 830 ° C in a 10% solution of NaCl and aging at 440 ° C for 3 hours, and kept at room temperature for 160 days (3840 hours).

Example 1

A sheet 5 mm thick of alloy G75D25 (of the following chemical composition: Mn 73.7%; Cu 25%; Fe 0.8%; S 0.25%; P 0.25%; total impurity content 1.3%) after thermal optimal treatment and aging were heated to a temperature of 50 ± 5 ° C, kept at this temperature for 1 h and cooled in air to room temperature.

Example 2

A sheet 5 mm thick of alloy G75D25 (of the following chemical composition: Mn 73.7%; Cu 25%; Fe 0.8%; S 0.25%; P 0.25%; total impurity content 1.3%) after thermal optimal treatment and aging were heated to a temperature of 200 ± 5 ° C, kept at this temperature for 1 h and cooled in air to room temperature.

Example 3

A sheet 5 mm thick of alloy G75D25 (of the following chemical composition: Mn 73.7%; Cu 25%; Fe 0.8%; S 0.25%; P 0.25%; total impurity content 1.3%) after thermal optimal treatment and aging were heated to a temperature of 450 ± 5 ° C, kept at this temperature for 1 h and cooled in air to room temperature.

The test data for the mechanical properties of the G75D25 alloy after heat treatment (TO) are given below.

Note: σ _in means temporary tensile strength;

σ _0.2 means the conditional elastic limit;

δ means elongation;

HV means Vickers hardness;

Ψ means relative energy dissipation (damping ability);

E is the modulus of normal elasticity (Young's modulus).

As follows from the data in table 1, the mechanical properties of the G75D25 alloy after aging at room temperature for 160 days (3840 hours) do not significantly change, and the damping ability is 50% lower than after heat treatment at the optimum mode. After heating, the method according to the invention is completely restored to the previous level.

The test data of the mechanical properties of alloys of the Mn-Cu system with different Mn contents are shown below in table 2.

Sheets of 5 mm thick from alloys of the Mn-Cu system were heat-treated according to the regime consisting in quenching from 830 ° С in a 10% solution of NaCl and aging at 450 ° С for 2 hours, and then kept at room temperature for 160 days ( 3840 hours). According to example 2, presented above, after heat treatment and aging, the samples were heated to a temperature of 200 ± 5 ° C, kept at this temperature for 1 h and cooled in air to room temperature.

As follows from the data in table 2, in all investigated Mn-Cu alloys (36 ... 80% Mn), curing at room temperature for 160 days (3840 hours) reduces the damping ability, which is completely restored to the previous level after heating according to the invention way.

Recovery of functional properties after deformation

Sheets of 5 mm thick from alloys of the Mn-Cu system were thermally processed according to the regime consisting in quenching from 830 ° С in a 10% NaCl solution and aging at 450 ° С for 2 hours, and then deformed to different degrees of deformation (1-5 %). According to example 2, presented above, after heat treatment and aging, the samples were heated to a temperature of 200 ± 5 ° C, kept at this temperature for 1 h and cooled in air to room temperature.

Test data on the functional properties (Ψ,%) of alloys of the Mn-Cu system with different Mn contents are given below.

The data presented in table 3 indicate that the functional properties (Ψ,%) of Mn-Cu alloys decrease after plastic deformation (γ) by 2%. After annealing by the method proposed in the invention, the functional properties (Ψ,%) of Mn-Cu alloys are completely restored to the previous level.

The proposed method allowed to reduce the complexity and to accelerate the method of restoring a high level of functional properties of Mn-Cu alloys.

Claims (1)

A method of heat treating sheets of alloys of the Mn-Cu system, comprising restoring the damping ability of the sheets by heating, holding and cooling, characterized in that the restoration of the damping ability of the sheets is carried out by heating at a temperature of 150-400 ° C, holding time of at least 525 s per 1 mm sheet thickness and cooling at a rate of at least 2 ° C / s.