The working conditions for aluminum forging forging parts include factors such as force magnitude, vibration, working temperature, and corrosion. The technical requirements for aluminum forging should encompass two aspects: the shape, dimensions, and surface condition of the forging; as well as the structure and mechanical properties of the forging. To meet the usage requirements of the forging, the key is to correctly select the raw material for the forging, strictly control the production process and quality of the raw material, and achieve effective quality control through the rational formulation of forging production processes.
The selection of aluminum forging materials is typically determined by product design. In addition to the basic material properties such as yield strength, tensile strength, ductility, and fracture toughness, it is also crucial to consider the specific strength and stiffness of the material, as well as its physical properties, to reduce structural weight. Furthermore, process properties (such as ductility, hardening, cutting, welding, etc.) and the material's cost-effectiveness must be taken into account.
Selecting high-quality raw materials is the prerequisite for ensuring the quality of forgings, with the main factors determining material quality being material melting, ingot casting, and semi-finished product processing. The technical requirements for raw materials used in aviation forgings are summarized as follows:
Chemical composition
The content of alloy elements, harmful impurities, gases, and residual elements in the material shall comply with the technical standards and relevant technical conditions or technical agreements for aviation raw materials. If production conditions permit, the content of harmful elements, gases, and residual elements in the material should be controlled as much as possible. Uniform distribution of alloy elements is required.
2. Smelting Technology
Ultra-high strength steel, titanium alloys, and high-temperature alloys are produced using vacuum consumable arc remelting process, with titanium alloys and super alloys requiring at least two vacuum consumable remelting cycles. Alloy structural steels, stainless steels, and heat-resistant steels are produced through electric arc furnaces, electric arc furnace with electroslag remelting double melting process, or other superior melting methods. Aluminum alloys are typically melted in flame furnaces, resistance furnaces, and induction furnaces. A series of process measures should be taken to strictly control impurity content, enabling a variety of heat treatment states for the materials.
In accordance with the production process and quality requirements for aluminum forging, the types and specifications of materials include ingots, bars (rolled, forged, extruded), billets, flat materials, and cakes (circles) among others. When strict streamline distribution requirements are in place for forgings, attention should be given to selecting the streamline direction of the raw materials to coordinate with the specified streamline distribution of the forging. Surface defects of raw materials, such as cracks, folds, and thick skins, can easily lead to surface defects in forgings, so they should be limited. The dimensional tolerances of raw materials have a significant impact on the shaping of forgings, and thus, clear requirements have been proposed.
3. Material Forging Ratio
Ensure adequate deformation of the material, i.e., the forging ratio should be within an appropriate range to ensure complete deformation and reduce or eliminate casting structures within the material.
4. Mechanical Properties
The mechanical properties of raw materials include those at room temperature and high temperatures, such as strength indices, plasticity indices, impact toughness, hardness, fracture toughness, durability strength, creep limits, fatigue properties, and resistance to stress corrosion. These should be specified in the technical requirements of raw materials based on the type of forging and its application. Some mechanical property indicators of large raw materials may be lower, so attention should be paid to the design and selection of the material.
5. High Magnification
This encompasses the requirements for the microstructure, grain size (for steel), and purity of materials in the heat treatment state. The structure of the material has a decisive impact on its performance. Some abnormal structures within the raw material structure, such as austenitic and martensitic stainless steel, other steels, aluminum, magnesium alloys, titanium alloys, high-temperature alloys, and carbide segregation.
