Sharif Digital Repository

A method to reach the globular weld structure of A356 aluminum alloy using stirring the localized semisolid zone during butt-joining is developed. Since the heat conductivity of this alloy is very high, the accurate controlling of temperature during joining must be considered. A gas heating system was used to heat up the nitrogen gas up to the required temperature. A dried and free oxygen gas was prepared when a stream of nitrogen gas could pass closely around a hot element. Hot and pure nitrogen gas flow through a precise ceramic nozzle was used to create a localized semisolid pool. At this stage a fine stirrer was introduced into the weld seam in order to mix the two sides into a single...