Dissimilar Aluminium Alloys Welding by Friction Stir Processing and Reverse Rotation Friction Stir Processing

Abstract

Processing of friction is a method derived from the welding of stir, gives fine grains. In the present work, new methods were used, namely friction stir processing (FSP) and the reverse of rotation of stir processing. This work aims to investigate the effect of (FSP) and (RFP) techniques on the properties of welded specimens. The results obtained were good in comparison with the friction stir welding (FSW) which includes a one pass of the welded sample, (FSP) engaging two passes of welding in the same rotational direction, and the third method which also engages two passes of welding the first pass with a rotational speed in a counter clockwise and the second in clockwise. The joining of dissimilar AA 5052 and AA7075-T6, (3 mm) thickness was accomplished by using (FSP) and (RFSP) to be compared with (FSW) process in order to investigate the effect of these techniques on the properties of welded samples. The rotational speeds are (710, 1000 and 1500) RPM and one traverse speed of (60) mm/min. The tool which has been used in this process was steel tool (X38) with (18 mm) shoulder diameter and (4 mm × 3.5 mm) taper pin diameter. The results of the two techniques were compared with the results of (FSW) by using (tensile test and micro hardness ). In the tensile test, the results of (FSP) and (RFSP) were higher than that of (FSW) for all the rotational speeds of welding. In the micro hardness test, the values for all samples at the stir zone are higher than base metal of AA7075-T6 and lower than base metal of AA5052, the hardness of (FSP) and (RFSP) at speed of (710, 1000 and 1500) RPM was about one and half higher that of the metal of base for AA7075-T. The efficiency of tensile strength about (73.6%) for (FSP) and about (79.2 %) for (RFSP) as compared with the tensile strength of (FSW) and it is about (51.4%) at a speed of rotation (1000 rpm).