In this study, ETIAL 1050 H14 Al alloy plates of 3 mm thickness were joined by friction stir welding using a vertical milling machine at three different rotational speeds (720-910-1120 rpm) and at three different welding speeds (20-50-80 mm/minute). Grinding, polishing and etching were applied to the surface of the welded samples in order to ascertain the microstructure and micro hardness characteristics of the samples. Generally the hardness values of all the welded joints decreased from base the plate towards the stirred zone. Base metal exhibited elongated grains in rolling direction and its micro hardness was determined to be 45 HV. The heat affected zone displayed a coarse-grain structure and its micro hardness was 27-38 HV. The experiments have shown that the grains on the thermomechanically affected zone oriented towards the direction of the rotation of the stirring pin. The hardness of this zone was higher than that in the heat affected zone. It was also determined that fine equiaxed grains were formed in the stirred zone due to dynamic recrystallization.