The Effects of Welding Conditions on the Joint Characteristics of Friction Stir Welded Aluminum 3003 Alloy

Two-way factorial design method was applied to evaluate the joint strength of friction stir welded aluminum 3003 alloy in this study. The welding factors and levels were the tool rotation speeds of 1,300, 1,800, 2,300, and 2,800 rpm and the tool travel speeds of 150, 250, 350, and 450 mm/min under the shoulder diameter of 18 mm and pin diameter of 4 mm. The uniaxial tension tests were carried out for varience analysis of tensile strength of welded part, and micro-structure observations were also performed with hardness measurements at welded part. From the results, the variance analysis revealed that the contributions of welding factors on the tensile strength of the weld part were the rotation speed of 67.9% and the travel speed of 31.8%. The optimum condition for FSW was predicted the welding speed of 450 mm/min and rotating speed of 1,300 rpm, and the presumption range of tensile strength at optimal condition of reliability 95% was estimated to 135.53 ± 1.11 MPa. In addition, the lower the rotation speed and the higher the travel speed, the higher the tensile strength. Finally the hardness and grain size of optimal condition was higher and finer than that of lowest condition at weld part.