Method of machining of products out of aluminium grade a85 working under voltage relaxation conditions

FIELD: metallurgy.

SUBSTANCE: method of machining of products out of aluminium grade A85 working under stress relaxation conditions is performed by electric field action on the product, at that electrical potential is supplied to the products from stabilised power source, and average speed of voltages relaxation is increased by change of the specified potential within range from -1.5 V to 1.5 V.

EFFECT: control of voltage relaxation of technically clean Al grade A85.

1 tbl, 2 dwg

 

The invention relates to the field of treatment of metals and can be used to control the service life of products made from metals and operating in conditions of stress relaxation. In particular, the product can be used in the construction, manufacturing engines, automotive, Avio and shipbuilding, where the most widely used are metals. Stress relaxation is called spontaneous reduction of stresses in loaded rigid body at a constant total strain [1].

Known way to control the process of stress relaxation of the metal using a pulsed electric current with parameters 250 A/mm, t=10-4c, F=100 Hz [2], without power and at equivalent heating is a characteristic bend at the yield stress. thermal part of the current leads to relaxation to (4-5)·104PA or to an additional effect compared to the experience without current of 2·104PA. Collateral current thermal effect leads to an increase relaxedevening voltages approximately in 2 times. Found that when exposed to a pulsed electric current to the crystals, loaded above the yield limit, the observed increase in the depth of relaxation, i.e. the maximum effect of electron-plastic effect current has on the yield strength of crystals, which is clever�decreases by tens of percent, indicating a strong influence of current on the start process and dislocation. The ratio of the effective voltage and athermal components of the stress increases 8-10 times, indicating that the decrease in activation energy and activation volume of the process. This method increases the ductility and, consequently, enables acceleration of stress relaxation.

However, the disadvantage of this method include the inability to control the relaxation of polycrystalline materials.

The closest to the claimed is a method of controlling the creep of aluminium brand A, namely that the product of aluminum attach one of the metal plates with different aluminum work function [3]. If annexation occurs the contact potential difference. Depending on the magnitude of the contact potential difference of the creep process or slow connecting plates of Pb, Ti, Fe, Cu, or accelerate connecting plates of Zr, Ni. Increases the durability of aluminium products.

The disadvantage of this method is the limited range of emerging potential difference.

The object of the invention is to control the stress relaxation commercially pure Al brand A that will increase the accuracy of the stamping operations.

The method for handling goods� aluminum brand A, working in conditions of stress relaxation, is that the product, working in conditions of stress relaxation, the electric potential is applied in the range between -1.5 to 1.5 V from a stabilized power supply. When you change the electric potential of the sample average rate of stress relaxation increases, and the sign of the potential plays no role.

Description of the connection shown in Fig.1, gde - movable punch, 2 - stationary punch, 3 - the sample under test, 4 - power, 5 - wire, 6 - insulating layer.

Description of the method is illustrated by Fig.2. Fig.2 shows the dependence of the relative values of the average speed of relaxation from the electric potential.

The metal used for the conductor according to the law of the Volt has no effect. As a quantitative parameter to assess the influence of electric potential on the process of stress relaxation was chosen as the relative change of the average speed of relaxation of the stresses calculated by the ratio of:

ϑ=ΔσΔt

Δσ=σ0-σ,

ξ=ϑaϑ0ϑ0 ,

where ϑ is the average rate of stress relaxation,

Δσ - depth relaxation

Δt is the average time stress relaxation

σ is the stress at the end of test

σ0- the current voltage at the beginning of relaxation

ξ is a relative measure of the average speed of relaxation

ϑa- the speed of the end of stress relaxation

ϑ - speed tension relaxation

ϑ0- the speed at the beginning of the relaxation voltage

Data on the relative change of the average speed of stress relaxation in Al brand A given in the table.

Therefore, to accelerate the process of stress relaxation, it is advisable to use the change of energy state of metal surfaces, electrical potential using a stabilized power supply.

The potential φ, InThe relative change of the average speed of relaxation ξ
Of -1.50,31
-10,48
-0,50,09
00
0,50,11
10,49
1,50,25

From the table it is visible to non-monotonic dependence of the relative change of the average speed of stress relaxation in Al brand A the magnitude of the electric potential.

Sources of information

1. Bordiga, A. M. stress Relaxation in metals and alloys [Text] / A. M. Bordiga, L. B. Getsov. - M.: Metallurgy, 1978. - 256

2. Troitsky, O. A. Influence of electric current on the stress relaxation in crystals of Zn, Cd and Pb / O. A. Troitskii, V. I. Spitsyn, V. I. Stashenko, " DOKL. - 1978. - T. 241. - No. 2. Pp. 349-352.

3. Pat. 2433444. Russian Federation, M. CL. G05D11/00, C22F 3/02. A method of controlling the creep of aluminium brand A / Konovalov S. V., Zuev, L. B., philipiev R. A. [D. V., Danilov V. I., Gromov V. E. the Applicant and patent holder of the Siberian State Industrial University (RU). - 2010117981/02, Appl. 04.05.2010; Publ. 10.11.2011 bul. No. 31. - 7: Il.

A method of processing aluminum products brand A, working in conditions of stress relaxation by affecting the product of the electric field, characterized by the fact that the product from a stabilized power supply down the electric potential and increase the average rate of stress relaxation by the change in said potential range from -1.5 V to 1.5 V.



 

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