CN-119932450-B - Ladder controllable temperature annealing and deformation treatment process for improving damage resistance of aluminum-lithium alloy

Abstract

The invention discloses a step controllable temperature annealing and deformation treatment process for improving the damage resistance of an aluminum lithium alloy, which comprises the steps of carrying out deformation treatment on an aluminum lithium alloy cast ingot and then carrying out two-stage temperature control annealing treatment, wherein the two-stage annealing treatment is carried out according to the conditions of 300-320 ℃ in a first stage, 1-2h in a second stage, 320-400 ℃ in a second stage, 1-2h in a first stage, and the temperature rising rate in the second stage is 5-25 ℃ in a second stage. The damage resistance of the aluminum-lithium alloy is greatly improved through the synergistic effect of grain structure regulation and control and the second phase particles. The alloy material treated by the method can meet the industrial engineering production application requirements of high damage resistance of the aluminum lithium alloy for aerospace at present.

Inventors

• LI JINFENG
• LIU DANYANG
• LI HAORAN
• ZENG GUANGJUN
• CAI ZHIMIN
• CAI XUFENG
• LI ZHUORUI

Assignees

• 中南大学

Dates

Publication Date

20260512

Application Date

20250123

Claims (7)

1. 1. A step controllable temperature annealing and deformation treatment process for improving the damage resistance of an aluminum lithium alloy is characterized by comprising the steps of carrying out deformation treatment on an aluminum lithium alloy cast ingot, and then carrying out two-stage temperature control annealing treatment, wherein the two-stage annealing treatment is carried out according to the conditions of 300-320 ℃ in a first stage, 1-2h in a second stage, 320-400 ℃ in a second stage, 1-2h in a heating rate of 5-25 ℃ in the second stage; The alloy components of the aluminum lithium alloy comprise 3.9 wt percent of Cu, 1.3 percent wt percent of Li, 0.4 percent wt percent of Mg, 0.40 percent wt percent of Ag, 0.30 percent wt percent of Mn, 0.4 percent wt percent of Zn, 0.12 percent of Zr, and unavoidable impurities of <0.05 percent by weight, wherein iron is less than or equal to 0.02 percent by weight, silicon is less than or equal to 0.02 percent by weight, and the balance of Al.
2. 2. The step-controlled temperature annealing and deformation treatment process for improving the damage resistance of an aluminum-lithium alloy according to claim 1, wherein the deformation amount of the deformation treatment is 30-80%.
3. 3. The step-controlled temperature annealing and deformation treatment process for improving the damage resistance of an aluminum-lithium alloy according to claim 1, wherein the deformation treatment is cold rolling or hot rolling.
4. 4. The step temperature-controllable annealing and deformation treatment process for improving the damage resistance of the aluminum-lithium alloy according to claim 1, which is characterized by further comprising the steps of carrying out temperature-controllable solution treatment or solution treatment and aging treatment after the annealing treatment, wherein the temperature-controllable solution treatment system is as follows: The first stage is 320-340 ℃ per 2-4 h+the second stage is 510-520 ℃ per 1-2h, or, The first stage is 360-400 ℃ per 10-20 min +the second stage is 510-520 ℃ per 1-2h.
5. 5. The step-controlled temperature annealing and deformation treatment process for improving the damage resistance of an aluminum-lithium alloy according to claim 4, wherein the temperature rising rate from the first stage to the second stage in the solid solution treatment is controlled to be 10-20 ℃ per minute.
6. 6. The step-controllable temperature annealing and deformation treatment process for improving the damage resistance of the aluminum-lithium alloy according to claim 4, wherein the aging treatment system is 6% rolling pre-deformation +130-150 ℃ per 12-35 h.
7. 7. The step-controlled temperature annealing and deformation treatment process for improving the damage resistance of an aluminum-lithium alloy according to claim 1, further comprising homogenizing heat treatment before the deformation treatment.

Description

Ladder controllable temperature annealing and deformation treatment process for improving damage resistance of aluminum-lithium alloy Technical Field The invention belongs to the technical field of preparation and processing of aerospace craft structural materials, and particularly relates to a stepped controllable temperature annealing and deformation treatment process for improving the damage resistance of aluminum-lithium alloy. Background The aluminum-lithium alloy has excellent properties such as low density, high strength, high specific stiffness, high corrosion resistance and the like, is considered as a novel damage-resistant light structural alloy material with huge development potential, and has wide prospect in future deep application in the aerospace field. The novel ultrahigh-strength aluminum lithium alloy is hopeful to be a structural material of an aircraft by virtue of excellent mechanical properties. The aluminum-lithium alloy treated by the reasonable process has excellent strength and fatigue performance, and is expected to become a main force material of the skin, the longitudinal beam and the stringer materials of the cabin/pressure cabin of the current aircraft. However, the currently applied aluminum-lithium alloy brands still have a lot of gaps compared with the requirements of the damage resistance of the high-strength aluminum alloy. How to further improve the damage resistance of the material is important in a stress environment serving in cyclic loading. It is believed that the damage resistance of metals is closely related to grain structure, with major factors including grain size, grain orientation, and grain boundaries. Therefore, the grain structure characteristics of the alloy are regulated and controlled by regulating a heat treatment system, and further, the damage resistance of the alloy is improved, so that whether the alloy can be further applied in engineering or not is critical. Chinese patent CN 105755409a discloses that the aluminum-lithium alloy sheet cold-finish rolled to the final thickness is subjected to short-time annealing treatment at a certain temperature, then solution quenching and subsequent aging treatment to a desired state, and deformation energy storage caused by cold rolling is eliminated by the temperature change treatment at the second stage of annealing, so that the structure after solution treatment is changed into a partially recrystallized structure, thereby improving the damage resistance of the alloy. But the strength of the alloy is not high. Chinese patent CN113215423 a reports that the high strength damage-resistant aluminum-lithium alloy is obtained by casting the raw materials into ingots by melting, annealing the ingots, hot rolling, intermediate annealing, cold rolling into sheets, and then solution quenching, pre-deforming and aging. The method is complex in process, the axial grain content in the alloy is increased due to multiple annealing and deformation treatment, and the damage resistance of the obtained aluminum-lithium alloy is not improved. Therefore, there is a need for a heat treatment process that regulates the grain structure of an alloy to a stable and uniform state and optimally regulates the structure to an optimized grain structure morphology that is effective for damage suppression. Disclosure of Invention Based on the technical problems in the prior art, one of the purposes of the invention is to provide a step controllable temperature annealing and deformation treatment process for improving the damage resistance of aluminum-lithium alloy, wherein the heat treatment system comprises specific annealing temperature and fixed heat preservation time on the basis of combining certain deformation, so that the target ultrahigh-strength aluminum-lithium alloy has high damage resistance, and the requirements of the processing and use service performance of the aluminum-lithium alloy material for aerospace at present can be met. In order to achieve the above object, the technical scheme of the present invention is as follows: a step temperature-controllable annealing and deformation treatment process for improving the damage resistance of an aluminum lithium alloy comprises the steps of carrying out deformation treatment on an aluminum lithium alloy cast ingot, and then carrying out two-stage temperature-controllable annealing treatment, wherein the two-stage annealing treatment comprises a first stage 300-320 ℃ per unit time, a second stage 320-400 ℃ per unit time, and a heating rate of the second stage 5-25 ℃ per unit time. Further, the aluminum lithium alloy comprises AlCu 3.6-4.5Li1.0-2.0 X, wherein X comprises any one or more of Mg, ag, zn, mn, zr. Further, the deformation amount of the deformation treatment is 30-80%. Further, the temperature rising rate of the second stage is 5-25 ℃ per minute. Further, the deformation treatment is cold rolling or hot rolling. Further, the method further comprises the step of carryi