What are the technical requirements of forged aluminum for raw materials?

The selection of quality raw materials is a prerequisite for ensuring the quality of forgings. The main links that determine the quality of raw materials are smelting, ingot casting and semi-finished product processing. The technical requirements for raw materials used in forging aluminum can be summarized as follows:

1. Chemical composition

The content of alloying elements, harmful impurity elements, gases and residual elements in the material shall comply with the technical standards of wrought aluminum and the provisions of relevant technical conditions or technical agreements. As far as production conditions permit, the content of harmful elements, gases and residual elements in the material should be controlled as much as possible. There are certain requirements for the uniform distribution of alloying elements.

2. Melting process

Ultra-high strength steel, titanium alloy, and superalloy are produced by vacuum consumable remelting process. Titanium alloy and superalloy require no less than secondary vacuum consumable remelting. Alloy structural steel, stainless steel, heat-resistant steel are produced by electric arc furnace, electric arc furnace plus electroslag remelting double melting process or other better melting methods. Aluminum alloys are usually melted by flame furnaces, resistance furnaces and induction furnaces. Aluminum alloys also need to take a series of technological measures to strictly control the impurity content and diversify the heat treatment state of the material.

According to the production process and quality requirements of forged aluminum, the specifications of materials include ingots, bars (rolled materials, forged materials, extruded materials), square billets, flat materials, cakes (rings), etc. When the forgings have strict streamline distribution requirements, attention should be paid to the selection of the streamline direction of the raw materials to coordinate the streamline distribution specified by the forgings. Surface defects of raw materials, such as cracks, folds, scars, heavy skin, etc., can easily lead to surface defects of forgings, so they should be limited. The dimensional tolerances of the raw materials have an important influence on the formation of the forgings and therefore have clear requirements for them.

3. Material forging ratio

Make sure that the material has a large enough deformation, that is, the size of the forging ratio should be within an appropriate range to ensure that the material is sufficiently deformed to reduce or eliminate the casting structure in the material. For large aviation forgings, the forging ratio of raw materials is generally greater than 6-8.

4. Mechanical properties

The mechanical properties of raw materials include mechanical properties at room temperature and high temperature, such as strength index, plastic index, impact toughness, hardness, fracture toughness, permanent strength, creep limit, fatigue performance, stress corrosion resistance, etc., should be based on the use of forged aluminum. Different regulations and are grown within the technical requirements of the raw materials. Some mechanical properties of large raw materials are low, and attention should be paid to the design and selection of materials.

5. High magnification tissue

It is a requirement for the microstructure, grain size (steel) and purity of the raw material in the final heat-treated state. The organization of a material has a decisive influence on its properties. Some abnormal structures in the raw material structure, such as microstructure defects such as austenitic and martensitic stainless steel, other steels, aluminum, magnesium alloys, titanium alloy structures, superalloys, carbide segregation, banded structures, etc., the intrinsic grain size of steel Excessive thickness and low purity will not only seriously affect the performance of forgings, but also increase the scrap rate of forgings. Therefore, forged aluminum has clear requirements for the high-strength structure of raw materials, which are specified in relevant technical standards.