Method for eliminating residual stress of aluminum alloy die forging piece

An aluminum alloy mold and residual stress technology, which is applied in the field of aluminum alloy material processing, can solve the problems of effective residual stress elimination effect, etc., and achieve the effects of residual stress reduction, improvement of dimensional stability, and improvement of service life.

Active Publication Date: 2019-01-01
HUNAN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0011] In short, the above methods have some defects and limitations in the process of use, and are effective for the elimination of residual stress.

Method used

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  • Method for eliminating residual stress of aluminum alloy die forging piece

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0034] Samples were taken from 7050 aluminum alloy forgings and cut into 7050 aluminum alloy plate samples of 80mm×40mm×10mm. After the sample was solidified at 480°C for 1 hour, it was quickly put into water at 20°C for quenching, and the quenching holding time was 40 minutes; the quenched sample was cold-pressed, and the cold-pressing deformation was 3%; The sample was placed in -196°C liquid nitrogen for cryogenic treatment, and the cryogenic holding time was 10 minutes; then it was taken out and placed in a heat treatment furnace at 120°C for rapid heating and double-stage aging treatment, and the aging temperature and holding time were 120°C×6h+170 °C×12h, the heating rate of the die forging from 120 °C to 170 °C is 3 °C / min. The transfer interval between each pass is less than 2 hours. The residual stress changes at different heat treatment stages are shown in Table 1. After solid solution + 20°C water temperature quenching + cold pressing + deep cooling + aging treatm...

Embodiment 2

[0038] Samples were taken from 7050 aluminum alloy forgings and cut into 7050 aluminum alloy plate samples of 80mm×40mm×10mm. After the sample was solidified at 460°C for 1 hour, it was quickly put into 40°C water for quenching, and the quenching holding time was 20 minutes; the quenched sample was cold-pressed, and the cold-pressing deformation was 4%; The samples were placed in 196°C liquid nitrogen for cryogenic cooling, and the cryogenic holding time was 40 minutes; then they were placed in a heat treatment furnace for rapid heating and double-stage aging treatment, and the aging temperature and holding time were 120°C×6h+180°C×13h double Stage aging treatment, the heating rate of the die forging from 120°C to 180°C is 3.5°C / min. The residual stress changes at different heat treatment stages are shown in Table 1. The equivalent residual stress value on the surface of the sample dropped from 160.8MPa after quenching to 12.5MPa, and the residual stress was eliminated by mor...

Embodiment 3

[0042] The difference from Example 1 is that the cold deformation is 6%, the equivalent residual stress value on the surface of the sample drops from 165.8MPa after quenching to 24.6MPa, and the residual stress is 85%. After cryogenic treatment, the sample The intensity is 505MPa.

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Abstract

The invention discloses a method for eliminating residual stress of an aluminum alloy die forging piece. The method comprises the following steps: step 1: carrying out cold pressing on the aluminum alloy die forging piece subjected to solution hardening treatment; step 2: carrying out deep cooling treatment on the forging piece subjected to the cold pressing; step 3: carrying out rapid temperature-rising double-grade ageing treatment on the forging piece subjected to the deep cooling treatment; step 4: carrying out air cooling on the forging piece subjected to the rapid temperature-rising double-grade ageing treatment. Aiming at reducing the residual stress, a cold pressing finishing die is used for carrying out cold-pressing deformation on the die forging piece firstly; then the die forging piece is put into liquid nitrogen and is subjected to the deep cooling treatment; then the temperature of the forging piece subjected to the deep cooling treatment is rapidly raised and the double-grade ageing treatment is carried out. The residual stress of the aluminum alloy die forging piece can be reduced by 90 percent or more through treatment of a solution hardening, cold pressing, deep cooling and ageing combined technology; the method is especially suitable for the large-size and high-strength aluminum alloy die forging pieces with complicated shapes.

Description

technical field [0001] The invention belongs to the technical field of aluminum alloy material processing, and in particular relates to a method for eliminating residual stress of aluminum alloy die forgings. Background technique [0002] 7050 aluminum alloy has good comprehensive properties such as high strength, high toughness, and corrosion resistance. It is an Al-Zn-Mg-Cu series ultra-high-strength deformed aluminum alloy widely used in large forgings and thick plates in the aviation field. The alloy needs to be solution treated at a high temperature of about 470°C and artificially aged after rapid quenching to obtain excellent comprehensive mechanical properties. However, during the quenching and cooling process, due to the fast cooling rate, the temperature gradient between the core and the surface of the component is large. Generally, compressive stress is formed on the surface and tensile stress is formed on the core. The maximum stress value can reach more than 200M...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22F1/053C22C21/10
CPCC22C21/10C22F1/002C22F1/053
Inventor 袁武华朱佳佳傅强
Owner HUNAN UNIV
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