ABSTRACT
Superplasticity is defined by an extended plastic deformation previous to fracture, generally at high temperatures. In the mode of fine structures superplasticity, grain boundary sliding is the controlling mechanism. To achieve this fine grained structure it could be used any Severe Plastic Deformation (SPD) process like Friction Stir Processing (FSP). Nevertheless, it must be consider the thermal stability of the microstructure produced, which is related to its capacity to resist heating without experiment abnormal grain growth. The use of magnesium alloys has been promoted in the automotive industry in order to reduce weight of the structures.
The aim of this work is to study the thermal stability of the AZ31 friction stir processed microstructure. Sheets of 3 mm thickness were obtained in as cast condition. These sheets were FSProcessed. Samples of AZ31 FSPed were heat treated to 300, 350, 400 and 450 ºC, during 10, 30 and 60 min. These 12 conditions plus the base material were microstructurally characterized. Vickers microhardness profiles were also measured. Grain growth kinetics was analyzed and related with time and temperature.
Keywords
Magnesium alloys; Friction-Stir Processing; thermal stability; grain size
