【Mechanical Equipment Technology Exchange Edition】Mechanical Equipment 【Daily Question】20190625

This post was last edited by wangld on 2019-6-26 08:11. The degree of plastic deformation has a significant impact on the microstructure and properties of metals. The degree of deformation is too low to achieve the goal of refining grains and improving the mechanical properties of the metal ； Excessive deformation not only fails to further improve mechanical properties but also leads to the formation of fibrous structures, increasing the anisotropy of the metal. When the deformation exceeds the metal’s allowable limit, defects such as cracking occur.

Effects of plastic deformation on texture and structure: 1) Formation of fibrous texture – The grains are elongated or flattened in the direction of deformation; impurities are distributed in thin bands or chains. 2) Deformation texture (1) Deformation texture: A structure in polycrystalline materials in which the grains exhibit preferential orientation as a result of plastic deformation. (2) Wire texture: A certain crystal orientation tends to be parallel to the direction of deformation. (Formed during drawing) Planar texture: A certain crystal plane tends to be parallel to the rolling direction, while a certain crystal axis tends to be parallel to the main deformation direction. (formed during rolling or extrusion) 3) Formation of dislocation cells (substructures): After significant deformation, due to the movement and interaction of dislocations, these dislocations are distributed unevenly, causing the grains to break down into many subgrains with slightly different crystal orientations. A large number of dislocations accumulate at the subgrain boundaries, while the dislocation density inside is relatively much lower. As the deformation amount increases, the resulting substructures become finer. An increase in the dislocation density throughout the grain reduces the material’s corrosion resistance. Effect on mechanical properties: After deformation, the material undergoes work hardening, resulting in a significant increase in strength and hardness, while plasticity and toughness decrease markedly. Engineering significance of work hardening: 1. Work hardening is an important method for strengthening materials, especially those metal materials that cannot be strengthened through heat treatment methods. 2 Work hardening facilitates uniform deformation of metals. Because the hardened area resulting from the deformation of the metal causes further deformation to occur primarily in the areas that remain undeformed or are only slightly deformed. 3. Work hardening makes further deformation of the metal difficult and accelerates the wear of the mold, which is undesirable when large amounts of deformation are required of the material. During the deformation and processing of metals, \"intermediate annealing\" is often necessary to eliminate these adverse effects, thereby increasing energy consumption and costs.

1) Changes in grain shape； 2) Substructures are formed within the grains ； 3 Grain orientation change ； As the degree of deformation increases, the strength and hardness of the metal increase, while its plasticity and toughness decrease.

Effect on metal microstructure: The microstructure of the metal undergoes changes in terms of grain shape and size, substructure, etc., as well as the development of deformation textures. Impact on performance: Mechanical properties undergo significant changes, and physical and chemical properties also change.

The effect of plastic deformation on the microstructure and properties of metal materials is quite significant, mainly manifested in an increase in strength and hardness as well as a decrease in ductility. This change in properties is mainly caused by the changes in the internal microstructure of the metal material during plastic deformation.

1. Effects of plastic deformation on microstructure and structure 1) Formation of fibrous structure: Grains are elongated or flattened in the direction of deformation; impurities are distributed in thin bands or chains. 2) Deformation texture (1) Deformation texture: A structure in polycrystalline materials in which the grains exhibit preferential orientation as a result of plastic deformation. (2) Wire texture: A certain crystal orientation tends to be parallel to the direction of deformation. (Face/plate texture formed during drawing): A certain crystal face tends to be parallel to the rolling direction, while a certain crystal axis tends to be parallel to the main deformation direction. (formed during rolling or extrusion) 3) Formation of dislocation cells (substructures): After significant deformation, due to the movement and interaction of dislocations, these dislocations are distributed unevenly, causing the grains to break down into many subgrains with slightly different crystal orientations. A large number of dislocations accumulate at the subgrain boundaries, while the dislocation density inside is relatively much lower. As the deformation amount increases, the resulting substructures become finer. An increase in the dislocation density throughout the grain reduces the material’s corrosion resistance. /2. Effect on mechanical properties: After deformation, the material undergoes work hardening, resulting in a significant increase in strength and hardness, while plasticity and toughness decrease markedly. Engineering significance of work hardening: 1. Work hardening is an important method for strengthening materials, especially those metal materials that cannot be strengthened through heat treatment methods. 2 Work hardening facilitates uniform deformation of metals. Because the hardened area resulting from the deformation of the metal causes further deformation to occur primarily in the areas that remain undeformed or are only slightly deformed. 3. Work hardening makes further deformation of the metal difficult and accelerates the wear of the mold, which is undesirable when large amounts of deformation are required of the material. During the deformation and processing of metals, \"intermediate annealing\" is often necessary to eliminate these adverse effects, thereby increasing energy consumption and costs.

An increase in strength and hardness, along with a decrease in ductility. This change in properties is mainly caused by the changes in the internal microstructure of the metal material during plastic deformation.

The degree of plastic deformation has a significant impact on the microstructure and properties of metals. The degree of deformation is too low to achieve the goal of refining grains and improving the mechanical properties of the metal ； Excessive deformation not only fails to further improve mechanical properties but also leads to the formation of fibrous structures, increasing the anisotropy of the metal. When the deformation exceeds the metal’s allowable limit, defects such as cracking occur.

Effects of plastic deformation on texture and structure: 1) Formation of fibrous texture – The grains are elongated or flattened in the direction of deformation; impurities are distributed in thin bands or chains. 2) Deformation texture (1) Deformation texture: A structure in polycrystalline materials in which the grains exhibit preferential orientation as a result of plastic deformation. (2) Line (thread) texture: A certain crystal orientation tends to be parallel to the direction of deformation (as occurs during drawing). (3) Planar (plate) texture: A certain crystal plane tends to be parallel to the rolling surface, while a certain crystal orientation tends to be parallel to the main direction of deformation. (formed during rolling or extrusion) 3) Formation of dislocation cells (substructures): After significant deformation, due to the movement and interaction of dislocations, these dislocations are distributed unevenly, causing the grains to break down into many subgrains with slightly different crystal orientations. A large number of dislocations accumulate at the subgrain boundaries, while the dislocation density inside is relatively much lower. As the deformation amount increases, the resulting substructures become finer. An increase in the dislocation density throughout the grain reduces the material’s corrosion resistance.