Porosity refers to the void spaces in a material. These voids often occur as defects in cast metal components, due to shrinkage and gas bubbles as the liquid metal cools and solidifies, and present possibilities for component failure, such as fatigue, if they are not treated.
Metals generally shrink as they solidify; if there is not enough metal to compensate for the shrinkage then defects can form. Shrinkage defects can be closed or open, meaning that closed defects are contained within the metal (shrinkage porosity) or form on the surface of the metal. Another type of porosity, gas porosity, occurs after the metal has cooled due to the release of dissolved gas from the liquid metal.
Porosity can be detected using non-destructive testing techniques such as radiography (x-ray) or ultrasonic inspection and can be effectively eliminated by hot isostatic pressing.
See also macroporosity, microporosity.
Porosity refers to the void spaces in a material. These voids often occur as defects in cast metal components, due to shrinkage and gas bubbles as the liquid metal cools and solidifies, and present possibilities for component failure, such as fatigue, if they are not treated.
Metals generally shrink as they solidify; if there is not enough metal to compensate for the shrinkage then defects can form. Shrinkage defects can be closed or open, meaning that closed defects are contained within the metal (shrinkage porosity) or form on the surface of the metal. Another type of porosity, gas porosity, occurs after the metal has cooled due to the release of dissolved gas from the liquid metal.
Porosity can be detected using non-destructive testing techniques such as radiography (x-ray) or ultrasonic inspection and can be effectively eliminated by hot isostatic pressing.
See also macroporosity, microporosity.
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