(Session 11A)EVALUATION OF FRICTION STIR LAP WELDED ALUMINIUM ALLOY TO HIF-GA STEEL SHEET JOINT BY MODIFIED DIGITAL X-RAY RADIOGRAPHY AND ULTRASONIC B SCANNING

摘要

The dissimilar friction stir lap welded joints of aluminium sheet (AA 6061) of 2 mm thickness and zinc coated steel sheet of 1 mm thickness produced by different combination of rotational speed and travel speed have been analyzed by modified digital X-Ray radiography and ultrasonic B scan imaging to detect flaws/defects in the joints. In modified digital X-Ray radiography methodology uses digital frame integration for acquisition of data to reduce the image noise followed by high-pass filtering to sharpen the image by gradient operation and contrast adjustments to detect micro defects in FSW joints. The new methodology has resulted in three-fold increase in signal-to-noise ratio (SNR) with improved defect detection sensitivity. Radiographic techniques are most suitable for detecting volumetric flaws and ultrasonic testing gives the best possible chance of detecting planar flaws. Accordingly, both radiography and ultrasonic C and B scanning have been employed to characterize the flaws of dissimilar FSW joint.