A method for continuous aging heat treatment of metal strips and wires using electric current constant temperature

Abstract

The present invention discloses a method for continuous aging heat treatment of metal strips and wires, comprising the following steps: dividing the part of the metal strips and wires that passes through the treatment area during the continuous treatment process into a starting section and a stable section; heat treating the metal strips and wires in one of a mixed current treatment method, a current treatment and cooling treatment method, and an external heat source heating and current treatment treatment method; the process flow of the mixed current treatment method is: using a large current to treat the starting section, and using a small current to treat the stable section; the process flow of the current treatment and cooling treatment method is: using a large current to treat the starting section, and forcing cooling to the stable section; the process flow of the external heat source heating and current treatment treatment method is: using a small current to simultaneously treat the starting section and the stable section, using an external heat source to heat the starting section, and naturally cooling the stable section. The present invention can enable the metal strips and wires to reach a stable temperature during the heat treatment process.

Description

Technical Field

[0001] The invention belongs to the technical field of metal heat treatment, and in particular relates to a method for continuous aging heat treatment of metal plates, strips and wires using electric current constant temperature. Background Art

[0002] During the heat treatment of metal plates, strips and wires, especially for the aging process, the appropriate temperature can promote the more stable nucleation of solute atoms and form more precipitation phases. However, when the temperature is too high, the critical nucleation radius is large, and the chemical potential energy of nucleation is insufficient to nucleate. The temperature cannot be too low, otherwise the atoms cannot diffuse. For C7025 copper alloy, the aging temperature is 350-550℃. The precipitation efficiency of aging treatment below 350℃ is low, and the precipitation phase is coarse above 550℃. In order to accelerate the precipitation of precipitation phases, continuous aging treatment is generally carried out using current to reduce the aging treatment time from 8h to less than 30min. However, due to the accumulation of resistance heat in the continuous treatment process of the plate, strip and wire using current, the temperature between the two electrodes rises, making it difficult to form a stable temperature. Summary of the invention

[0003] In view of the problems in the prior art, the present invention provides a method for continuous aging heat treatment of metal plates, strips and wires using electric current and constant temperature. The present invention can enable the temperature of the metal plates, strips and wires to reach stability during the heat treatment process.

[0004] The present invention adopts the following technical solutions:

[0005] A method for continuous aging heat treatment of metal strips and wires using electric current constant temperature, comprising the following steps:

[0006] (1) The part of the metal plate, strip or wire that passes through the treatment area during the continuous aging heat treatment using electric current constant temperature is divided into the starting section and the stable section;

[0007] (2) The metal strip wire in step (1) is subjected to heat treatment using an electric current at a constant temperature to obtain the metal strip wire after aging heat treatment; the heat treatment method of the metal strip wire is one of a mixed current treatment method, a current treatment and cooling treatment method, and an external heat source heating and current treatment treatment method; the process flow of the mixed current treatment method is: a large current is used to treat the starting section, and a small current is used to treat the stable section; the process flow of the current treatment and cooling treatment method is: a large current is used to treat the starting section, and the stable section is forced to cool to achieve temperature stability; the process flow of the external heat source heating and current treatment treatment method is: a small current is used to simultaneously treat the starting section and the stable section, and an external heat source is used to heat the starting section, and natural cooling is used to make the temperature of the stable section constant.

[0008] Furthermore, the metal strip wire is a copper strip wire. The metal strip wire is divided into a starting section and a stable section. One end of the metal strip wire processing section is one end of the starting section, and the other end of the metal strip wire is one end of the stable section.

[0009] Furthermore, the continuous passage time of the starting section through the treatment area is 5s to 120s.

[0010] Furthermore, the treatment temperature of the initial stage in step (2) is 300°C-500°C.

[0011] Furthermore, the process flow of the mixed current treatment method in step (2) is as follows: an effective current of 50A / mm is used. 2 ~200A / mm 2 The high current treatment starting section uses an effective current of 0.1A / mm 2 ~50A / mm 2 The natural cooling of the metal strip and wire is basically equivalent to the heating power of the small current to achieve stability.

[0012] Furthermore, the process flow of the current treatment and cooling combination treatment in step (2) is as follows: the effective value current is 50A / mm 2 ~200A / mm 2 The high current processing starting section is used, and the stable section is air-cooled.

[0013] Furthermore, in step (2), the process flow of the external heat source heating and current treatment is as follows: the effective value current is 0.1A / mm 2 ~50A / mm 2 The starting section and the stable section are processed with a small current at the same time, and an external gradient heat source is used to heat the starting section, so that the starting section reaches the aging treatment temperature at a heating rate of 5℃ / s to 200℃ / s. The starting section is heated to 300℃ to 500℃ by a gradient heating method from high temperature to low temperature, and the stable section is cooled naturally. The starting section uses a heat treatment furnace to provide a gradient heating temperature from high to low, and then relies on natural cooling and the resistance heat offset of the current to reach a stable temperature. The three continuous current treatment methods enable the metal sheet, strip and wire to achieve temperature stability during the heat treatment process, and also realize current-assisted heat treatment, thereby improving the aging efficiency. The temperature of the metal sheet, strip and wire during the heat treatment process is less than or equal to the traditional aging treatment temperature of the metal.

[0014] Furthermore, in step (2), the gradient temperature difference of the external heat source used in the heating start section is 20°C to 500°C.

[0015] Furthermore, in step (2), the gradient temperature difference of the external heat source used in the heating start section is 20°C to 500°C.

[0016] Furthermore, in step (2), the treatment temperature of the mixed current treatment method is 300° C.-500° C., and the treatment time is 10 s-30 min.

[0017] Furthermore, in step (2), the treatment temperature of the current treatment and cooling combined treatment method is 300° C.-500° C., and the treatment time is 10 s-30 min.

[0018] Furthermore, in step (2), the treatment temperature of the combined treatment of external heat source heating and electric current treatment is 300° C.-500° C., and the treatment time is 10 s-30 min.

[0019] Beneficial technical effects of the present invention: The present invention designs a relevant solution to the problem that a stable temperature cannot be formed during the process of using electric current to continuously aging heat treat metal plates, strips and wires. The method of the present invention achieves that most areas of the metal plates, strips and wires are in constant temperature aging treatment during the continuous current treatment process by designing the pulse current treatment method and introducing appropriate cooling. The method of the present invention uses segmented pulse current treatment, segmented control of external environmental temperature, and cooling control of different sections. The purpose of offsetting the thermal effect of the current is achieved by means of natural cooling, external environment temperature supplementation in the low temperature section, and forced cooling, thereby achieving a stable temperature. The present invention can make full use of the heat treatment effect generated by direct current treatment of metals, stabilize the heat treatment temperature of metal plates, strips and wires, and realize isothermal current treatment, thereby improving the controllability of current treatment. In addition, the present invention can achieve heat treatment under high current or low current density according to actual working conditions. The present invention uses pulse current to heat treat metal plates, strips and wires at a constant temperature, which can effectively improve the control of pulse current aging treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of a constant temperature continuous aging heat treatment in a mixed current treatment method;

[0021] Figure 2 It is a schematic diagram of a constant temperature continuous aging heat treatment in which current treatment and cooling are combined;

[0022] Figure 3 Schematic diagram of constant temperature continuous aging heat treatment using a combination of external heat source heating and electric current treatment. DETAILED DESCRIPTION

[0023] See also Figure 1-3The method of the present invention relies on the cooperation of a large current or a heat treatment furnace with a small current to make the metal sheet, strip and wire reach the aging heat treatment temperature, and then use forced cooling or natural cooling to offset the resistance heat generated by the current, so as to achieve the purpose of maintaining the temperature of the metal sheet, strip and wire in the subsequent aging heat treatment process stable, and at the same time realize direct heat treatment with current. A large current refers to a current that can achieve the temperature of the metal sheet, strip and wire to reach the specified temperature for heat treatment within 5s-120s, while a small current is a current that uses this current alone to heat the metal to a temperature lower than the specified temperature for heat treatment. The constant temperature section can be the remaining part of the metal sheet, strip and wire processing section, and the constant temperature is controlled within ±10°C with the specified heat treatment temperature. Forced cooling is air cooling, and the air cooling power is determined based on the specified processing temperature and the current processing power.

[0024] The technical solution of the present invention is further explained below by way of embodiments.

[0025] Example 1

[0026] For the starting section of the cold-rolled C7025 copper strip, the effective current is 70A / mm 2 For the stable section at the back end, 25A / mm 2 The strip is treated with a small current. During the treatment process, the temperature of the strip is stabilized at 350°C, realizing the metal constant temperature full current aging treatment.

[0027] Example 2

[0028] For the starting section of the front section of the cold-rolled C7025 copper strip, the effective current is 150A / mm 2 For the stable section at the back end, 30A / mm 2 The strip is treated with a small current. During the treatment process, the temperature of the strip is stabilized at 410℃, realizing constant temperature full-current aging treatment of the strip.

[0029] Example 3

[0030] For the starting section of the front section of the cold-rolled C7025 copper strip, the effective current is 200A / mm 2 For the stable section at the back end, 45A / mm 2 The strip is treated with a small current. During the treatment process, the temperature of the strip is stabilized at 470°C, realizing constant temperature full-current aging treatment of the strip.

[0031] Example 4

[0032] For the starting section of cold-rolled C7025 copper strip, the effective current is 150A / mm 2The high current treatment lasted for 12s. For the stable stage, 35W wind power was used for cooling. During the treatment process, the temperature of the strip was stabilized at 500℃, achieving constant temperature aging treatment under high current density.

[0033] Example 5

[0034] For the starting section of the front section of the cold-rolled C7025 copper strip, the effective current is 100A / mm 2 The high current treatment lasts for 20s. For the stable section at the rear end, 30W wind power is used for cooling. During the treatment process, the temperature of the strip is stabilized at 450℃, achieving constant temperature aging treatment under high current density.

[0035] Example 6

[0036] For the starting section of the cold-rolled C7025 copper strip, the effective current is 70A / mm 2 The high current treatment lasts for 20s. For the stable section at the rear end, 20W wind power is used for cooling. During the treatment process, the temperature of the strip is stabilized at 500℃, achieving constant temperature aging treatment under high current density.

[0037] Example 7

[0038] For the starting section of cold-rolled C7025 copper strip, the effective current is 40A / mm. 2 The ambient temperature of the 200mm starting section is heated to 50℃~450℃ by electric furnace, and the temperature gradient is 400℃. The electric furnace heating is multi-stage control to achieve gradient temperature heating, and the heating temperature is high at the beginning and low at the end. For the stable section, the temperature of the strip is stabilized at 450℃ by natural cooling, realizing the constant temperature aging treatment of the metal strip under a single small current density.

[0039] Example 8

[0040] For the starting section of cold-rolled C7025 copper strip, the effective current used is 30A / mm 2 The ambient temperature of the 200mm starting section is heated to 330℃~350℃ by an electric furnace, with a temperature gradient of 20℃. The electric furnace heating is multi-stage controlled to achieve gradient temperature heating, with the heating temperature being high at the beginning and low at the end. During the treatment process, for the stable section of the strip line, the temperature of the strip wire is stabilized at 350℃ after natural cooling, realizing the constant temperature aging treatment of the metal under a single small current density.

[0041] The above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the same. Although the present invention has been described in detail with reference to the above embodiments, a person skilled in the art should understand that the specific implementation modes of the present invention can still be modified or replaced by equivalents, and any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be included in the scope of protection of the claims of the present invention.

Claims

1. A method for continuous aging heat treatment of metal strips and wires using electric current constant temperature, characterized in that: The following steps are involved: (1) The part of the metal strip wire that passes through the treatment area during the continuous aging treatment using electric current constant temperature is divided into the starting section and the stable section; (2) The metal strip wire in step (1) is subjected to heat treatment using an electric current constant temperature to obtain the metal strip wire after aging heat treatment; the heat treatment method of the metal strip wire is one of a mixed current treatment method, a current treatment and cooling treatment method, and an external heat source heating and current treatment treatment method; the process flow of the mixed current treatment method is: a large current is used to treat the starting section, and a small current is used to treat the stable section; the process flow of the current treatment and cooling treatment method is: a large current is used to treat the starting section, and the stable section is forced to cool; the process flow of the external heat source heating and current treatment treatment method is: a small current is used to simultaneously treat the starting section and the stable section, and an external heat source is used to heat the starting section, and the stable section is naturally cooled.

2. The method for continuous aging heat treatment of metal sheets, strips and wires using electric current constant temperature according to claim 1, characterized in that: The metal strip wire is a copper strip wire.

3. The method for continuous aging heat treatment of metal sheets, strips and wires using electric current constant temperature according to claim 1, characterized in that: The continuous passing time of the starting section through the treatment area is 5s to 120s.

4. The method for continuous aging heat treatment of metal sheets, strips and wires using electric current constant temperature according to claim 1, characterized in that: The treatment temperature of the initial stage in step (2) is 300°C-500°C.

5. The method for continuous aging heat treatment of metal sheets, strips and wires using electric current constant temperature according to claim 1, characterized in that: The process flow of the mixed current treatment method in step (2) is as follows: the effective current is 50A / mm 2 ~200A / mm 2 The high current treatment starting section uses an effective current of 0.1A / mm 2 ~50A / mm 2 The small current processing stable section.

6. The method for continuous aging heat treatment of metal sheets, strips and wires using electric current constant temperature according to claim 1, characterized in that: The process flow of the current treatment and cooling combination treatment in step (2) is as follows: the effective value current is 50A / mm 2 ~200A / mm 2 The high current processing starting section is used, and the stable section is air-cooled.

7. The method for continuous aging heat treatment of metal sheets, strips and wires using electric current constant temperature according to claim 1, characterized in that: The process flow of the external heat source heating and current treatment in step (2) is as follows: the effective value current is 0.1A / mm 2 ~50A / mm 2 The starting section and the stable section are treated with a small current at the same time, and an external gradient heat source is used to heat the starting section, so that the starting section reaches the aging treatment temperature at a heating rate of 5°C / s to 200°C / s, and the stable section is cooled naturally.

8. The method for continuous aging heat treatment of metal sheets, strips and wires using electric current constant temperature according to claim 7, characterized in that: The gradient temperature difference of the external heat source used in the heating starting section in step (2) is 20°C to 500°C.

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