Thermal treatment method for simultaneously improving strength and fatigue resistance property of aluminum alloy

A heat treatment method and anti-fatigue technology, which is applied in the field of heat treatment of metal materials, can solve the problems of reducing the degree of overaging at grain boundaries, reducing the stress corrosion resistance of alloys, and affecting the dispersion of precipitated particles at grain boundaries, so as to achieve good exfoliation corrosion resistance. Effect of high strength and improved fatigue performance

Active Publication Date: 2013-01-23
CENT SOUTH UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, lowering the regression temperature will inevitably reduce the overaging degree of the grain boundary and affect the dispersion of precipitated particles at the grain boundary, thereby reducing the stress corrosion resistance of the alloy.

Method used

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  • Thermal treatment method for simultaneously improving strength and fatigue resistance property of aluminum alloy
  • Thermal treatment method for simultaneously improving strength and fatigue resistance property of aluminum alloy
  • Thermal treatment method for simultaneously improving strength and fatigue resistance property of aluminum alloy

Examples

Experimental program
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Effect test

Embodiment 1

[0042] Example 1 (T6 state);

[0043] The composition of alloy 1 is: 5.9%Zn, 2.4%Mg, 2.4%Cu, 0.6%Mn, 0.05%Zr, and the balance is aluminum. Solution treatment at 460°C for 2 hours, water quenching, air cooling after single-stage aging at 70°C / 96h, mechanical properties at room temperature: tensile strength 616MPa, yield strength 556MPa, elongation 13%; corrosion resistance Performance: Conductivity is 24.6%IACS, in standard corrosion solution (3.0%NaCl+0.5%H 2 o 2 ) and the fracture time under the load of 452MPa is 24 hours, and the corrosion current is 945 / uA·cm -2 .

Embodiment 2

[0044] Example 2 (RRA1 state);

[0045] The composition of alloy 2 is: 5.9%Zn, 2.4%Mg, 2.0%Cu, 0.4%Mn, 0.05%Zr, and the balance is aluminum. Solution treatment at 470°C for 2h, and water quenching, air cooling after 100°C / 24h+150°C / 2min+100°C / 24h three-stage aging, the mechanical properties at room temperature reach: the tensile strength is 601MPa, the yield strength is 544MPa, elongation 12%; corrosion resistance: electrical conductivity 30.6%IACS, in standard corrosion solution (3.0%NaCl+0.5%H 2 o 2 ) and the fracture time under the load of 452MPa is 10 hours, and the corrosion current is 493 / μA·cm -2 .

Embodiment 3

[0046] Example 3 (RRA2 state);

[0047] The composition of alloy 3 is: 8.4%Zn, 2.3%Mg, 2.2%Cu, 0.6%Mn, 0.15%Zr, and the balance is aluminum. Solution treatment at 495°C for 1 hour, water quenching, air cooling after 70°C / 24h+170°C / 20min+100°C / 96h tertiary aging, the mechanical properties at room temperature reach: tensile strength 630MPa, yield strength is 566MPa, elongation 11%; stress corrosion resistance: electrical conductivity 34.6%IACS, in standard corrosion solution (3.0%NaCl+0.5%H 2 o 2 ) and the fracture time under 452MPa load is 50 hours, and the corrosion current is 190 / μA·cm -2 ; Anti-fatigue performance: ΔK=29MPam 1 / 2 ,da / dN=2.0×10 -3 mm / cycle.

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Abstract

The invention relates to a thermal treatment method for simultaneously improving the strength and fatigue resistance property of aluminum alloy. The method comprises the following steps of: heating aluminum/zinc/magnesium/copper alloy subjected to solution treatment for 2 hours at the temperature of 460-495 DEG C to 70-120 DEG C, and carrying out heat preservation for 24-96 hours; then carrying out heat preservation for 2-120 minutes at the temperature of 150-170 DEG C, and cooling to room temperature; and subsequently, carrying out heat preservation for 24-96 hours at the temperature of 70-120 DEG C, and then discharging and performing air cooling, wherein the aluminum/zinc/magnesium/copper alloy comprises the following components: Zn, Mg, Cu, Mn, Zr and Al. The thermal treatment provided by the invention is simple and reasonable in technology; through three-stage aging thermal treatment technology, the grain boundary of the aluminum/zinc/magnesium/copper alloy is in an overaging state, and the structure in the grain mainly consists of eta ' phase and a G.P. zone; and the overaging structure of the grain boundary is good in corrosion resistance, and the G.P. zone particles in the grain are beneficial to reciprocating slippage and crack closing dislocated under the alternating stress action, so that the fatigue resistance property is improved, and the alloy is good in stress corrosion resistance property and exfoliation corrosion resistance property and is suitable for industrial application.

Description

technical field [0001] The invention discloses a heat treatment method for simultaneously improving the strength and fatigue resistance of aluminum alloys; in particular, it relates to a heat treatment method for simultaneously improving the strength and fatigue resistance of aluminum-zinc-magnesium-copper alloys. The invention belongs to the technical field of metal material heat treatment. Background technique [0002] The Al-Zn-Mg-Cu alloy with high Zn content has a tensile strength exceeding 600MPa, and has a wide range of applications in many fields such as aerospace. In the past, only the strength and corrosion resistance of Al-Zn-Mg-Cu alloys were often concerned. With the development of aviation technology, especially with the development of damage tolerance design theory, for Al-Zn-Mg-Cu alloy, not only the aluminum alloy is required to have ultra-high strength and excellent corrosion resistance, but also requires excellent corrosion resistance. fatigue performanc...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22F1/053
Inventor 刘志义夏鹏高丽芳陈旭林茂陈来
Owner CENT SOUTH UNIV
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