Hardness and Heat Deformation of LSAW Steel Pipe
Sources: this site Click: Date: 2013-7-12 11:57:13
The metal in the external force will change size and shape. called deformed. Deformation typically consist of two elastic and plastic deformation. Elastic deformation is reversible when the external force is removed, the deformation can be fully recovered; irreversible plastic deformation, when the external force is removed, there is still residual strain.
When the metal is plastically deformed, the strength and hardness of the metal increases, and its decrease in ductility and toughness is called cold deformation hardening (also known as work-hardening). Causes cold deformation strengthening, and is generally considered in the plastic deformation process, with increasing deformation, dislocation density increases, and a series of interactions that dislocation motion is blocked; while grains also appear broken into thin strip, grain boundaries become blurred, the formation of so-called "fibrous tissue." The greater the degree of deformation of the metal, the dislocation density is greater, the greater the resistance to dislocation motion, the larger the plastic deformation resistance, its strength and hardness increased, while the plasticity and toughness decrease.
Cold deformation strengthening has important significance in the actual production. First, this is an important means of strengthening the material, especially for the heat treatment cannot be enhanced by longitudinal materials, even more important. Secondly, cold deformation strengthening favours uniform deformation of the metal. Because the generation of the deformed portion of metal hardening, the deformation will cause less distortion to the undeformed part, or continue to develop. Third, cold deformation strengthening can improve the security component, component once the overload plastic deformation during use due to strengthening effect, prevents members suddenly break. However, cold deformation strengthening Longitudinal also continue to deform difficult, or even cracks. Thus, the metal deformation and the process often a "intermediate annealing" to eliminate its adverse effects.
When the metal is plastically deformed, the strength and hardness of the metal increases, and its decrease in ductility and toughness is called cold deformation hardening (also known as work-hardening). Causes cold deformation strengthening, and is generally considered in the plastic deformation process, with increasing deformation, dislocation density increases, and a series of interactions that dislocation motion is blocked; while grains also appear broken into thin strip, grain boundaries become blurred, the formation of so-called "fibrous tissue." The greater the degree of deformation of the metal, the dislocation density is greater, the greater the resistance to dislocation motion, the larger the plastic deformation resistance, its strength and hardness increased, while the plasticity and toughness decrease.
Cold deformation strengthening has important significance in the actual production. First, this is an important means of strengthening the material, especially for the heat treatment cannot be enhanced by longitudinal materials, even more important. Secondly, cold deformation strengthening favours uniform deformation of the metal. Because the generation of the deformed portion of metal hardening, the deformation will cause less distortion to the undeformed part, or continue to develop. Third, cold deformation strengthening can improve the security component, component once the overload plastic deformation during use due to strengthening effect, prevents members suddenly break. However, cold deformation strengthening Longitudinal also continue to deform difficult, or even cracks. Thus, the metal deformation and the process often a "intermediate annealing" to eliminate its adverse effects.
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