Method and device for synergistically improving the rollability and the strength of rolled magnesium alloys

Abstract

The application discloses a method and device for synergistically improving the rollability and plate strength of a magnesium alloy, and belongs to the technical field of metal material processing. The method comprises the following steps: step S1, low-temperature homogenization treatment of a magnesium alloy ingot blank: placing the magnesium alloy ingot blank in a heating furnace, and performing heat preservation under a condition lower than a conventional rolling heating temperature until a temperature field of the ingot blank in a thickness direction reaches uniformity; step S2, selective heating of a surface layer of the magnesium alloy ingot blank; and step S3, gradient temperature field rolling of the magnesium alloy ingot blank. According to the method, the ideal temperature gradient of "outer heating and inner cooling" is actively constructed at a rolling instant through the synergistic process of "low-temperature homogenization pretreatment" and "surface layer induction heating". The method can not only ensure high-temperature plasticity of the surface layer to prevent cracking, but also ensure low-temperature strength of a core, and significantly refines the overall organization through thermal coupling, so that the stability of a rolling process and the comprehensive strength of a rolled plate are synergistically improved.

Description

Technical Field

[0001] This invention relates to the field of metal material processing technology, and specifically to a method and apparatus for synergistically improving the rollability and strength of magnesium alloys. Background Technology

[0002] Magnesium alloys, as the lightest metallic structural materials, have broad application prospects in aerospace, transportation, and 3C electronics products. Rolling is a key plastic processing technology for obtaining high-performance magnesium alloy sheets. However, magnesium alloys have a close-packed hexagonal crystal structure, few independent slip systems at room temperature, and poor plastic deformation capacity, resulting in poor rollability, especially prone to cracking at low temperatures. Currently, in industrial production, to improve the rollability of magnesium alloys, a common process is to heat and hold the ingot at a high temperature before rolling. This traditional method has the following inherent defects: (1) The contradiction between surface cracking and core softening is difficult to reconcile: During the rolling process, the surface of the billet is in direct contact with the low-temperature rolls and air, resulting in rapid heat dissipation and a temperature distribution of "cold outside and hot inside". This temperature field is superimposed on the rolling stress field (tensile stress on the surface and compressive stress on the core), resulting in a narrow process window. If a higher heating temperature is used to ensure the plasticity of the surface layer and prevent cracking, the core will coarsen or soften excessively after rolling due to excessive temperature, which will damage the overall strength of the plate. Conversely, if a lower heating temperature is used to maintain the strength of the core, the surface layer will crack due to insufficient temperature and poor plasticity.

[0003] (2) High energy consumption and poor uniformity of structure and properties: The overall high temperature heating not only consumes a lot of energy, but also easily leads to uneven structure and properties of the board along the thickness direction. The surface layer may undergo dynamic recrystallization due to high temperature and large deformation, resulting in finer grains; while the core undergoes small deformation at high temperature, and the grains may remain coarse, forming an obvious performance gradient, which affects the overall performance of the board.

[0004] (3) Insufficient flexibility in process control: The temperature field of the traditional heating furnace is fixed before the rolling begins after the heat preservation. It cannot be dynamically adjusted according to the real-time status of the rolling process, making it difficult to accurately meet the rolling requirements of ingots with different alloy compositions and different specifications.

[0005] Therefore, developing a new method and apparatus that can synergistically improve the rollability of magnesium alloys and simultaneously enhance the overall strength of rolled plates is of great significance for promoting the preparation and application of high-performance magnesium alloy plates. Summary of the Invention

[0006] The purpose of this invention is to provide a method and apparatus for synergistically improving the rollability and strength of magnesium alloys.

[0007] The objective of this invention is achieved through the following technical solution: A method for synergistically improving the rollability and sheet strength of magnesium alloys includes the following steps: Step S1, Low-temperature homogenization treatment of magnesium alloy billet: The magnesium alloy billet is placed in a heating furnace and kept at a temperature lower than that of conventional rolling heating until the temperature field of the billet in the thickness direction becomes uniform. Step S2, Selective heating of magnesium alloy billet surface: The billet after S1 is transported to the entrance side of the rolling mill. Before rolling, the surface of the billet is selectively heated by induction heating. The induction heating parameters are controlled so that the heating energy mainly acts on the surface of the billet to a preset depth, and the surface temperature of the billet after heating is higher than the core temperature, forming a temperature gradient of external heat and internal cold. Step S3, Gradient Temperature Field Rolling of Magnesium Alloy Ingot: The ingot with the external hot and internal cold temperature gradient is immediately fed into the rolling mill for rolling deformation to obtain magnesium alloy rolled plate.

[0008] Furthermore, in step S2, the parameters for induction heating are controlled to satisfy the following condition: after heating, the temperature difference between the surface layer and the core of the ingot is 30°C to 150°C.

[0009] Furthermore, in step S2, the preset depth is 10% to 35% of the total thickness of the billet.

[0010] Further, in step S1, the holding temperature of the heating furnace is 200°C to 350°C; and / or, in step S2, the surface temperature of the ingot is raised to 350°C to 450°C through induction heating.

[0011] Furthermore, in step S2, an infrared thermometer or thermocouple is used to monitor the temperature of the surface and core of the ingot in real time, and the parameters of the induction heating are dynamically adjusted according to the monitoring results.

[0012] An apparatus for synergistically improving the rollability and sheet strength of magnesium alloys, comprising: A support platform, the height of which is adjustable, is used to carry and transport magnesium alloy ingots; one end of the support platform is set on the roll inlet side of the rolling mill, and the other end of the support platform is equipped with a heating furnace; the heating furnace is used to heat and hold the magnesium alloy ingots until the temperature field of the ingots in the thickness direction becomes uniform. A conveying module, mounted on the support platform, is used to drive the ingot to move along the feed direction; An induction heating module is disposed above and / or below the support platform and located on the conveying path of the conveying module, for selectively heating the surface of the ingot as it passes through. A temperature measuring unit is used to monitor the temperature of the ingot before and after heating; A heat insulation module is disposed between the induction heating module and the rolling mill rolls to block the influence of the induction heating module on the rolling mill rolls.

[0013] Furthermore, the temperature measuring unit includes a first temperature measuring instrument before heating for monitoring the surface temperature of the billet and a second temperature measuring instrument before heating for monitoring the core temperature of the billet; it also includes a first temperature measuring instrument after heating for monitoring the surface temperature of the billet and a second temperature measuring instrument after heating for monitoring the core temperature of the billet, wherein the first temperature measuring instrument before heating, the first temperature measuring instrument after heating, the second temperature measuring instrument before heating, and the second temperature measuring instrument after heating are all communicatively connected to the control system of the induction heating module.

[0014] Furthermore, the conveying module includes a plurality of drive rollers embedded in the support platform, and a power system for driving the drive rollers to rotate, wherein the power source of the power system is an electric motor.

[0015] Furthermore, the heat insulation module is made of a non-magnetic, high-temperature resistant material and serves as a physical partition between the induction heating module and the roll.

[0016] Furthermore, the induction heating module is a medium-frequency or high-frequency electromagnetic induction heater, and its power and frequency are adjustable.

[0017] The beneficial effects of this invention are: This application's method utilizes a synergistic process of "low-temperature homogenization pretreatment" and "pre-rolling surface induction heating" to actively construct an ideal temperature gradient of "external heat and internal cold" during rolling. This method ensures both high-temperature plasticity of the surface layer to prevent cracking and low-temperature strength of the core, while achieving significant refinement of the overall microstructure through thermo-mechanical coupling, thereby synergistically improving the stability of the rolling process and the overall strength of the rolled sheet. Attached Figure Description

[0018] Figure 1 This is a flowchart of the method of the present invention; Figure 2 This is a schematic diagram of the structure of the device of the present invention.

[0019] In the diagram: 1. Support platform; 2. Conveying module; 3. Induction heating module; 4. Temperature measuring unit; 5. Heat insulation module; 6. Rolling mill; 7. Heating furnace; 41. First temperature measuring instrument before heating; 42. Second temperature measuring instrument before heating; 43. First temperature measuring instrument after heating; 44. Second temperature measuring instrument after heating; 45. Control system. Detailed Implementation

[0020] The embodiments of this disclosure will now be described in detail with reference to the accompanying drawings.

[0021] The following specific examples illustrate the implementation of this disclosure. Those skilled in the art can easily understand the advantages and effects of this disclosure from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of this disclosure, and not all of them. This disclosure can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this disclosure. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. Based on the embodiments in this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure.

[0022] like Figure 1 As shown, a method for synergistically improving the rollability and strength of magnesium alloy sheets includes the following steps: Step S1, Low-temperature homogenization treatment of magnesium alloy ingot: The magnesium alloy ingot is placed in a heating furnace and kept at a temperature lower than that of conventional rolling heating until the temperature field of the ingot in the thickness direction is uniform; the holding temperature of the heating furnace is 200℃ to 350℃.

[0023] Step S2, Selective Heating of the Surface of Magnesium Alloy Ingot: The ingot processed in S1 is conveyed to the inlet side of the rolling mill. Before rolling, the surface of the ingot is selectively heated using induction heating. The induction heating parameters are controlled so that the heating energy mainly acts on the surface of the ingot to a preset depth, and the surface temperature of the ingot is higher than the core temperature after heating, forming a temperature gradient of external heat and internal cold. The induction heating parameters are controlled to meet the following: after heating, the temperature difference between the surface and core of the ingot is 30°C to 150°C. The preset depth is 10% to 35% of the total thickness of the ingot. The temperatures of the surface and core of the ingot are monitored in real time using an infrared thermometer or thermocouple, and the induction heating parameters are dynamically adjusted according to the monitoring results. Through induction heating, the surface temperature of the ingot is raised to 350°C to 450°C.

[0024] Step S3, Gradient Temperature Field Rolling of Magnesium Alloy Ingot: The ingot with the external hot and internal cold temperature gradient is immediately fed into the rolling mill for rolling deformation to obtain magnesium alloy rolled plate.

[0025] This method utilizes a synergistic process of "low-temperature homogenization pretreatment" and "pre-rolling surface induction heating" to actively construct an ideal temperature gradient of "external heat and internal cold" during rolling. This method ensures both high-temperature plasticity of the surface layer to prevent cracking and low-temperature strength of the core, while achieving significant refinement of the overall microstructure through thermo-mechanical coupling, thereby synergistically improving the stability of the rolling process and the overall strength of the rolled sheet.

[0026] likeFigure 2 As shown, an apparatus for synergistically improving the rollability and sheet strength of magnesium alloys includes... The support platform 1, which is height adjustable, is used to carry and transport magnesium alloy ingots; one end of the support platform 1 is set on the roll inlet side of the rolling mill 6, and the other end of the support platform 1 is equipped with a heating furnace 7; the heating furnace 7 is used to heat and keep the magnesium alloy ingots warm until the temperature field of the ingots in the thickness direction becomes uniform.

[0027] The conveying module 2 is disposed on the support platform and is used to drive the ingot to move along the feed direction. The conveying module 2 includes a plurality of drive rollers embedded in the support platform, the plurality of drive rollers are arranged in a row, and also includes a power system for driving the drive rollers to rotate, the power source of the power system being an electric motor.

[0028] An induction heating module 3 is disposed above and / or below the support platform and located on the conveying path of the conveying module, for selectively heating the surface of the ingot as it passes through; the induction heating module is a medium-frequency or high-frequency electromagnetic induction heater, the power and frequency of which are adjustable.

[0029] Temperature measuring unit 4 is used to monitor the temperature of the ingot before and after heating; the temperature measuring unit 4 includes a first temperature measuring instrument 41 for monitoring the surface temperature of the ingot before heating and a second temperature measuring instrument 42 for monitoring the core temperature of the ingot before heating; it also includes a first temperature measuring instrument 43 for monitoring the surface temperature of the ingot after heating and a second temperature measuring instrument 44 for monitoring the core temperature of the ingot after heating, and the first temperature measuring instrument 41, the first temperature measuring instrument 43, the second temperature measuring instrument 42, and the second temperature measuring instrument 44 before heating are all communicatively connected to the control system 45 of the induction heating module.

[0030] A heat insulation module 5 is disposed between the induction heating module and the rolling mill rolls to block the influence of the induction heating module on the rolling mill rolls. The heat insulation module 5 is made of a non-magnetic, high-temperature resistant material and serves as a physical partition between the induction heating module and the rolling mill rolls.

[0031] In the description of this invention, it should be understood that the terms "middle," "length," "upper," "lower," "front," "rear," "vertical," "horizontal," "inner," "outer," "radial," "circumferential," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0032] In this invention, unless otherwise expressly specified and limited, the first feature "on" the second feature may be in direct contact with the first and second features, or indirect contact with the first and second features through an intermediate medium. "A plurality of" means at least two, such as two, three, etc., unless otherwise expressly and specifically limited.

[0033] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0034] The above description is merely illustrative of the embodiments of the present invention and is not intended to limit the present invention. For those skilled in the art, any modifications, equivalent substitutions, improvements, etc., made without creative effort within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for synergistically improving the rollability and strength of magnesium alloy sheets, characterized in that, Includes the following steps: Step S1, Low-temperature homogenization treatment of magnesium alloy billet: The magnesium alloy billet is placed in a heating furnace and kept at a temperature lower than that of conventional rolling heating until the temperature field of the billet in the thickness direction becomes uniform. Step S2, Selective heating of magnesium alloy billet surface: The billet after S1 is transported to the entrance side of the rolling mill. Before rolling, the surface of the billet is selectively heated by induction heating. The induction heating parameters are controlled so that the heating energy mainly acts on the surface of the billet to a preset depth, and the surface temperature of the billet after heating is higher than the core temperature, forming a temperature gradient of external heat and internal cold. Step S3, Gradient Temperature Field Rolling of Magnesium Alloy Ingot: The ingot with the external hot and internal cold temperature gradient is immediately fed into the rolling mill for rolling deformation to obtain magnesium alloy rolled plate.

2. The method for synergistically improving the rollability and strength of magnesium alloys as described in claim 1, characterized in that: In step S2, the parameters for induction heating are controlled to satisfy the following condition: after heating, the temperature difference between the surface layer and the core of the ingot is 30°C to 150°C.

3. The method for synergistically improving the rollability and sheet strength of magnesium alloys as described in claim 1, characterized in that: In step S2, the preset depth is 10% to 35% of the total thickness of the billet.

4. The method for synergistically improving the rollability and strength of magnesium alloys as described in claim 1, characterized in that: In step S1, the holding temperature of the heating furnace is 200°C to 350°C; and / or, in step S2, the surface temperature of the ingot is raised to 350°C to 450°C by induction heating.

5. The method for synergistically improving the rollability and strength of magnesium alloys as described in claim 1, characterized in that: In step S2, an infrared thermometer or thermocouple is used to monitor the temperature of the surface and core of the ingot in real time, and the parameters of the induction heating are dynamically adjusted according to the monitoring results.

6. An apparatus for implementing the method for synergistically improving the rollability and sheet strength of magnesium alloys as described in any one of claims 1-5, characterized in that, include: A support platform, the height of which is adjustable, is used to carry and transport magnesium alloy ingots; one end of the support platform is set on the roll inlet side of the rolling mill, and the other end of the support platform is equipped with a heating furnace; the heating furnace is used to heat and hold the magnesium alloy ingots until the temperature field of the ingots in the thickness direction becomes uniform. A conveying module, mounted on the support platform, is used to drive the ingot to move along the feed direction; An induction heating module is disposed above and / or below the support platform and located on the conveying path of the conveying module, for selectively heating the surface of the ingot as it passes through. A temperature measuring unit is used to monitor the temperature of the ingot before and after heating; A heat insulation module is disposed between the induction heating module and the rolling mill rolls to block the influence of the induction heating module on the rolling mill rolls.

7. The apparatus for the method of synergistically improving the rollability and strength of magnesium alloys as described in claim 6, characterized in that: The temperature measuring unit includes a first temperature measuring instrument before heating for monitoring the surface temperature of the billet and a second temperature measuring instrument before heating for monitoring the core temperature of the billet; it also includes a first temperature measuring instrument after heating for monitoring the surface temperature of the billet and a second temperature measuring instrument after heating for monitoring the core temperature of the billet. The first temperature measuring instrument before heating, the first temperature measuring instrument after heating, the second temperature measuring instrument before heating, and the second temperature measuring instrument after heating are all communicatively connected to the control system of the induction heating module.

8. The apparatus for the method of synergistically improving the rollability and strength of magnesium alloys as described in claim 6, characterized in that: The conveying module includes several drive rollers embedded in the support platform, and a power system for driving the drive rollers to rotate, wherein the power source of the power system is an electric motor.

9. The apparatus for the method of synergistically improving the rollability and strength of magnesium alloys as described in claim 1, characterized in that: The heat insulation module is made of non-magnetic, high-temperature resistant material and serves as a physical partition between the induction heating module and the roll.

10. The apparatus for the method of synergistically improving the rollability and strength of magnesium alloys as described in claim 1, characterized in that: The induction heating module is a medium-frequency or high-frequency electromagnetic induction heater, and its power and frequency are adjustable.

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