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Chung tay xây dựng cộng đồng 
Cấp bậc: Binh nhì
Tham gia: 10/1/2023
Bài viết: 11
Đánh giá: [0]
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Annealing is a heat treatment process that changes the physical and sometimes chemical properties of a material to increase ductility and reduce hardness, making it easier to process.
The annealing process requires the material to remain above its recrystallization temperature for a set period of time before cooling. The cooling rate depends on the type of metal being annealed. For example, ferrous metals such as steel are usually cooled to room temperature in still air, while copper, silver, and brass can be cooled slowly in air or quenched quickly in water.
The heating process causes atoms to migrate in the crystal lattice and the number of dislocations decreases, resulting in changes in ductility and hardness. Heat-treated material recrystallizes when cooled. Grain size and phase composition depend on heating and cooling rates, which in turn determine material properties.
Hot or cold working of metal parts after annealing will again change the material structure, so further heat treatment may be required to achieve the desired properties.
However, with knowledge of the material composition and phase diagram, heat treatment can soften the metal and prepare it for further processing, such as forming, shaping, and stamping, and prevent brittle failure.
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