Mechanical Manufacturing Technologies, Safeyt and Its Measures at Work, Technology of mechanical manufacture

Quenching technology in the aviation field, let you change the heat treatment by the second

Every perfect flight depends on the professional aluminum alloy processing technology to protect the escort. The specific reason is that Houghton Yaogong will tell you carefully! metal stamping service

Aluminum alloy application

Many different types of aluminum alloys have been used in early aviation aircraft because aluminum alloys have been subjected to heat treatment to achieve high strength and high corrosion resistance, but they are lightweight; they are extremely flexible and formable. Mechanical processing, and low cost. At present, it has become the most commonly used material in modern aviation, and is widely used in the manufacture of modern commercial aircraft and military aircraft, such as Boeing 777, Airbus A380, Boeing UCAV-Unmanned Air Fighting Vehicle and Boeing F/A-18E/ F.

However, the premise of the application of aluminum alloys in the aerospace field is heat treatability. Recently, more attention has been paid to how to minimize the cost of 7075 and 7040 alloy sheet forgings by heat treatment. Manufacturers of aircraft skeletons have attempted heat treatment while rolling aluminum, which is machined into large ribs and bulkheads after heavy machining. metal stamping service

However, strict control is required for the heat treatment of aluminum alloys. In order to obtain a repeatable result and high-quality products, aircraft component manufacturers, suppliers and heat treatment manufacturers have now developed a series of specifications, the most used of which is the AMS-2770 specification – “heat treatment of aluminum parts”.

Heat treatment of aluminum

The heat treatment of aluminum includes two processes of solution treatment and aging treatment, wherein the solution treatment is to heat aluminum and its alloy to a temperature slightly lower than the eutectic melting temperature (close to the eutectic melting temperature to be in the solid solution) The amount of solid solution solute is maximized and maintained at this temperature for a sufficient period of time to bring the material close to the complete solid solution. After the solution treatment, the workpiece is rapidly cooled to dissolve the solute completely in the supersaturated solid solution. The solid solution and cooling treatment of these alloys are carried out in a dedicated large-scale high-temperature furnace. metal stamping service

Used for solid solution treatment of aluminum alloy
Quenched large bottom discharge furnace

After cooling, the alloy needs to be naturally aged. The improved performance is due to the rapid formation of the GP zone (Guinier-Preston) from the supersaturated solid solution and the quenching vacancies. After about 4 to 5 days, the strength increases rapidly and the performance is stable. T3 and T4 are the natural heat treatment processes after 4 days of natural aging. However, most aerospace aluminum alloys are artificially aged. Different aluminum alloys have a variety of different aging curves, but for the highest performance, higher aging temperatures and shorter aging times are usually required. When the aging temperature is high, the time required to obtain the desired performance is shorter. For this reason, it is generally preferred to select a lower aging temperature to ensure that the desired performance is obtained without causing overaging due to a rapid rise in temperature, and instead risking performance degradation. metal stamping service

The aging process of 7075 aluminum alloy:
(A) the initially formed GP area;
(B) formation of the GP region and the η’ phase of the semi-coherent precipitate;
(C) formation of a semi-coherent precipitate η’ and a coherent equilibrium precipitate η phase;
(D) Equilibrating the precipitate of the η phase of the precipitate.

Defect in heat treatment

During the process, there are some defects in the parts, and most of these defects are accompanied by heat treatment of aluminum, including solution treatment and quenching and cooling. Defects in solution treatment include oxidation, initial melting, and underheating. The defects in the quenching and cooling process are caused by some special warpage, or because the quenching medium used is too slow, the desolvent precipitation reaction is caused during the cooling process, and the improper performance and inappropriate The degree of saturation. metal stamping service

Abnormal quenching and clamping, resulting in deformation of large aircraft ribs

Deformation due to clamping. The reason is that the part is not properly supported

Countermeasure analysis

a. Oxidation during solution treatment
If the part is exposed to high temperatures for too long, oxidation can become a problem, possibly due to moisture in the air during the actual solution treatment. Eliminating moisture can alleviate the problem of surface bubbles. It can also be prevented by using ammonium fluoroborate. For large extrusions and forgings, anodizing the part is also an alternative to using ammonium fluoroborate. metal stamping service

b. Deformation during quenching
Of all the possible “impacts” in aluminum alloys due to heat treatment, quenching deformation is the most common. In order to solve the problem of deformation, the parts should be fully supported during the clamping, so that the load received is equally divided over a large area; the parts can be loosely bundled with the line during solution treatment to prevent mutual interaction between the parts. Collision; the part is preferably filled in to aerodynamics to avoid deformation of the part, which should be smoothly and stably quenched into the medium. In particular, in the aluminum alloys of the aerospace industry, PAG (Polyalkylene Glycol)-based polymer quenching media have been successfully used to control and minimize quenching deformation. metal stamping service

Several stages of quenching medium of PAG-based polymer during quenching

If the heat treatment is carried out properly, sufficient metal processing properties can be ensured. Although quenching takes only a few seconds in the production process of a part, this process can significantly affect the overall quality and service life of the part. metal stamping service

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