The method of processing of alloys of the aluminum-magnesium

 

(57) Abstract:

The invention relates to metallurgy, in particular to methods for semi-finished products of aluminium-magnesium alloys. Proposed method of treatment, including cooling after hot rolling with a speed of 0.001 - 0,015oWith a/C, subsequently repeated cold rolling with intermediate annealing and final annealing, heating under which is conducted at a speed of not less than 2oWith a/C, exposure is carried out for 4 - 300 C and cooled at a rate not less than 0,5oWith a/C. In the case of obtaining a thin ribbon, the cooling at the last intermediate annealing in the process of repeated cold rolling is carried out with a speed of 0.001 - 0,015oC/S. the Method according to the invention provide improved corrosion resistance. 1 C. p. F.-ly, 1 table.

The invention relates to metallurgy, in particular to methods for semi-finished products of aluminium-magnesium alloys.

Method of heat treatment of aluminum-magnesium alloys, mainly used nowadays in industry, includes the operation of the final annealing comprising heating the alloy to a temperature above the temperature of the end of recrystallization (Tp With/h (0,033aboutC/C) (see "Production instruction map; PI.255-83, "Heat treatment of semi-finished products and parts from aluminum and aluminum alloys", S. 8). The disadvantage of this method is that this method is time-consuming and energy-intensive, and aluminum-magnesium alloys processed by this method have a high enough resistance to stress corrosion cracking.

A method of processing aluminum-magnesium alloys, including hot rolling, cooling, multiple cold rolling with intermediate annealing, heating to a temperature of final annealing, exposure at this temperature and cooled adopted for the prototype (Industrial aluminum alloys. M. Metallurgy, 1984. The Handbook, edited by A. F. Belov and others). The disadvantage of this method is the complexity, power consumption. Aluminum-magnesium alloys processed by this method, have a reduced resistance to stress corrosion cracking corrosion and dissecting.

We propose a method of treatment of the alloys of the aluminum-magnesium includes hot rolling, cooling, multiple cold rolling with intermediate annealing, heating to a temperature of final annealing, seperatory final annealing lead with speed of not less than 2aboutWith a/C, maintained at this temperature range 4-300 C and cooled at a rate not below 0.5aboutWith a/C. During repeated cold rolling after the last intermediate annealing cooling is carried out with a speed of 0.001-0,015aboutC/C to obtain thin sheets.

The difference of the proposed method against known is that the cooling after hot rolling produce at the rate of 0.001-0,015aboutWith a/C. Heating to a temperature of final annealing is conducted at a speed of not less than 2aboutWith/with extract, the final annealing is 4-300 and with the cooling from the temperature of the annealing is conducted at a speed of not less than 0,5aboutWith a/C. During repeated cold rolling, after the last intermediate annealing cooling is carried out with a speed of 0.001-0,015aboutC/C to obtain thin sheets.

The technical result of the proposed method is to increase the resistance to stress corrosion cracking and dissecting corrosion for alloys of the aluminum-magnesium and increase the life of the structures.

The proposed mode allows you to create a structure with a uniform distribution of phases on the grain volume. Uniform distribution-phase leads to a uniform protein sow, that provides increased resistance to stress corrosion cracking corrosion and dissecting.

Cooling after hot rolling and intermediate annealing before the final stage of cold rolling at speeds less than 0,001aboutWith/with or larger than 0,015aboutWith a/C, heating and cooling to a temperature of final annealing at a speed less than 2 and 0.5aboutC/s, respectively, the duration of annealing with more than 300 leads to the selection-phase partially along the grain boundaries in the form of a solid film. This emphasis-phase localizes to corrosion processes and lowers resistance to stress corrosion cracking corrosion and dissecting.

At exposure times of less than 4 to get a recrystallized structure, which contributes to the directed flow of corrosion processes and reduces the resistance to stress corrosion cracking corrosion and dissecting.

The upper limit of the speed of heating and cooling is determined by the technical capabilities of the equipment.

Examples of the method.

Ingots size HH mm of alloy AMg6 and AMg5 was heated to 400aboutWith, spent the hot rolling, and then received the 60% to a thickness of 2 mm and was heated to a temperature of final annealing of this alloy 310aboutWith different speeds, kept at the temperature of annealing different times and cooled at different speeds.

Some ingots of alloy AMg5 got a thin strip of 1 mm with intermediate anneals (example 4). For comparison, sheets of alloy AMg6 were manufactured by a known method prototype.

Tests on stress corrosion cracking was performed on samples by the method specified tensile loads according to GOST 9.019-74 at a voltage of 140 MPa.

Tests on dissecting corrosion was carried out according to GOST 9.904-82.

Comparative data on resistance to stress corrosion cracking, dissecting corrosion in the table.

The table shows that the sheets are made on the proposed modes (examples 1-4), have the highest resistance to stress corrosion cracking, dissecting corrosion. This allows you to extend the life of structures made of alloys of the aluminum-magnesium 18-20%

1. The METHOD of PROCESSING of ALLOYS of the ALUMINUM-MAGNESIUM, including hot rolling, cooling, multiple cold rolling with intermediate annealing, heating to a temperature of final annealing, followed by exposure at this pace>the/C, heating to a temperature of final annealing is conducted at a speed of not less than 2oC/C and holding at that temperature 4 300 C, and a final cooling lead with a speed of not less than 0,5oWith/s

2. The method according to p. 1, characterized in that the cooling after the last intermediate annealing during repeated cold rolling lead with speed 0,001 0,015oWith a/C.

 

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