Processing method for eliminating residual stress of light alloy material

A technology of residual stress and treatment method, which is applied in the field of treatment to eliminate residual stress of light alloy materials, can solve the problems of small stress elimination rate and large strain, and achieve the effect of eliminating residual stress and improving toughness

Inactive Publication Date: 2019-05-14

青岛四通八达商贸有限公司

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AI-Extracted Technical Summary

Problems solved by technology

At present, in industrial production, pre-stretching is the most commonly used process for eliminating residual stress. It has the advantages of simple process, fast speed, and high stress relief rate, but it is not suitable ...

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Method used

[0033] The composition content of 7055 aluminum alloy is: Zn: 7%, Cu: 1.8%, Mg: 2.3%, Zr: 0.1%, and the balance is Al. The complex forging of 7055 aluminum alloy is subjected to forging deformation, and then it is subjected to solution trea...

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Abstract

The invention relates to a processing method for eliminating the residual stress of the light alloy material, and is suitable for eliminating the quenching residual stress of various shapes and size light alloy materials. The method comprises the following steps of after quenching treatment, carrying out cryogenic treatment on the light alloy material; after subzero treatment, rapidly transferringthe light alloy material into a steam box for quenching heat treatment; and then carrying out air cooling to room temperature. The method disclosed is not limited by the size and shape of the material, the residual stress of the light alloy material is greatly reduced, and the strength and toughness of the light alloy material are synchronously improved.

Technology Topic

Cryogenic treatmentAir cooling +6

Examples

Experimental program(3)

Example Embodiment

[0023] Example 1

[0024] Mg-8wt.%Al-0.4wt.%Zn magnesium alloy (AZ80 for short) is a commonly used commercial magnesium alloy with a thermal conductivity of about 82W/(m·K). It is produced by hot extrusion with a thickness of 290mm×230mm During the cross-section extrusion process, online quenching is performed by spraying room temperature (20℃) water. After quenching, there is a strong residual stress. Two 500mm long magnesium alloy bars are taken from adjacent positions of the same material for experimental comparison.

[0025] Place the light alloy material in an ultra-low temperature liquid nitrogen tank at -196℃ to ensure that the temperature of the core of the material is consistent with the surface temperature.

[0026] Cryogenic and rapid heat treatment: Place one of the above-mentioned magnesium alloy rods in a low-temperature liquid nitrogen box at a temperature of -196°C for 12 hours. The temperature of the core of the material is consistent with the surface temperature. After completion, transfer the magnesium alloy bar to a steam furnace within 2 minutes, and keep it at 150°C for 3 hours. The temperature of the core of the material is consistent with the surface temperature. After completion, place it in the air and cool to room temperature (18°C).

[0027] By comparison, it is found that magnesium alloy bars that have not undergone cryogenic and rapid heat treatment cracked during subsequent machining, while magnesium alloy bars that have undergone cryogenic and rapid heat treatment did not find any deformation during subsequent machining. After measurement, the residual stress relief rate of the magnesium alloy bar after deep cooling and rapid heat treatment is 86%. After the same follow-up treatment process, it was found that the tensile strength of the magnesium alloy bar without deep cold and rapid heat treatment was 370 MPa, and the tensile strength of the magnesium alloy bar after deep cold and rapid heat treatment was 390 MPa, an increase of about 10%.

Example Embodiment

[0028] Example 2

[0029] Mg-7wt.%Gd-5wt.%Y-1wt.%-0.5wt.%Zr magnesium alloy (EW75 for short) is a commonly used rare earth magnesium alloy with a thermal conductivity of about 40W/(m·K). Extrusion method produces 290mm×20mm thick extruded materials. In order to ensure the performance, room temperature water (20℃) is sprayed up and down for on-line quenching. After quenching, there is strong residual stress. The warpage of 2000mm long materials is 2mm.

[0030] Cryogenic and rapid heat treatment: Place the magnesium alloy strips in a low-temperature liquid nitrogen box at a temperature of -196°C for 3 hours, and the temperature of the core of the material is consistent with the surface temperature. After completion, transfer the magnesium alloy strips to a steam furnace within 2 minutes, and keep the temperature at 200°C for 1 hour. The temperature of the core of the material is consistent with the surface temperature. After completion, place it in the air and cool to room temperature (18°C).

[0031] After measurement, the residual stress relief rate of the magnesium alloy strip after cryogenic and rapid heat treatment is 95%, and no deformation is found in subsequent machining; the tensile strength of the magnesium alloy strip after cryogenic and rapid heat treatment is 460MPa, which is compared After deep cooling and rapid heat treatment, the magnesium alloy row material is increased by about 5-10%.

Example Embodiment

[0032] Example 3

[0033] The 7055 aluminum alloy composition content is: Zn: 7%, Cu: 1.8%, Mg: 2.3%, Zr: 0.1%, and the balance is Al. Forging deformation of 7055 aluminum alloy complex forgings, and then solution treatment, the solution temperature is 475 ℃ for 2 hours, and then immersed in room temperature water for cooling, forming a large residual stress, deformed in the subsequent machining process, scrapped The rate is high.

[0034] Cryogenic and rapid heat treatment: Place the aluminum alloy forgings in a low-temperature liquid nitrogen box at a temperature of -196°C for 6 hours, and the temperature of the core of the material is consistent with the surface temperature. After completion, the aluminum alloy forgings are transferred to the steam furnace within 2 minutes, and the temperature is kept at 160°C for 1 hour. The temperature of the core of the material is consistent with the surface temperature. After completion, place it in the air and cool to room temperature (18°C).

[0035] After measurement, the residual stress relief rate of the aluminum alloy forgings after cryogenic and rapid heat treatment is about 90%, and no deformation is found in the subsequent machining; the tensile strength of the aluminum alloy forgings after cryogenic and rapid heat treatment is 640MPa, which is more Cryogenic and rapid heat treatment of aluminum alloy forgings increases by about 5-10%.

[0036] The processing method for eliminating the quenching residual stress of the light alloy material is not limited by the size and shape of the material, greatly reducing the residual stress of the light alloy material, and simultaneously improving the strength and toughness of the light alloy material.

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PUM

Property	Measurement	Unit
Thermal conductivity	82.0	W/K/m
Tensile strength	370.0	MPa
Tensile strength	390.0	MPa
tensile		MPa
Particle size		Pa
strength	10

Description & Claims & Application Information

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Classification and recommendation of technical efficacy words

Improve toughness
Relief of residual stress

Processing method for eliminating residual stress of light alloy material

AI-Extracted Technical Summary

Problems solved by technology

Method used

Abstract

Examples

Example Embodiment

Example Embodiment

Example Embodiment

PUM

Description & Claims & Application Information

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