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| The '''heat-affected zone''' (HAZ) is the area of base material, either a [[metal]] or a [[thermoplastic]], which is not melted and has had its microstructure and properties altered by [[welding]] or heat intensive cutting operations. The heat from the welding process and subsequent re-cooling causes this change from the weld interface to the termination of the sensitizing temperature in the base metal. The extent and magnitude of property change depends primarily on the base material, the weld filler metal, and the amount and concentration of heat input by the welding process.
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| The [[thermal diffusivity]] of the base material plays a large role—if the diffusivity is high, the material cooling rate is high and the HAZ is relatively small. Alternatively, a low diffusivity leads to slower cooling and a larger HAZ. The amount of heat inputted by the welding process plays an important role as well, as processes like [[oxyfuel welding]] use high heat input and increase the size of the HAZ. Processes like [[laser beam welding]] and [[electron beam welding]] give a highly concentrated, limited amount of heat, resulting in a small HAZ. Arc welding falls between these two extremes, with the individual processes varying somewhat in heat input. To calculate the heat input for arc welding procedures, the following formula is used:
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| :<math>Q = \left(\frac{V \times I \times 60}{S \times 1000} \right) \times \mathrm{Efficiency}</math>
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| where ''Q'' = heat input ([[kilojoule|kJ]]/mm), ''V'' = voltage ([[Volt|V]]), ''I'' = current ([[Ampere|A]]), and ''S'' = welding speed (mm/min). The efficiency is dependent on the welding process used, with [[shielded metal arc welding]] having a value of 0.75, [[gas metal arc welding]] and [[submerged arc welding]], 0.9, and [[gas tungsten arc welding]], 0.8.
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| ==References==
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| *Weman, Klas (2003). Welding processes handbook. New York: CRC Press LLC. ISBN 0-8493-1773-8.
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| {{Metalworking navbox|weldopen}}
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| [[Category:Welding]]
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Latest revision as of 12:56, 6 January 2015
My namе is Walter (37 years old) and my hobbies aгe Knapping and Kayaking.
Feel freе to visit my homepage; Livejasmin Credits Hack