Consequently the tubes are MIAB welded (parameters as per trial 20 of Table 4) and radiography test is performed on the weld joint after removal of the reinforcement. The result is shown in Fig. 8. It is observed that the number of pores, has reduced to a greater extent even as compared to the result shown in Fig. 7. This concentration of pores is within the acceptable limits as per ASME section 5. Thus the study demonstates that the butt surface of the tubes must be free from impurities to get a better result for radiography test. These small number of pores may arise due to the interaction of the gas molecules in the weld region during the heating and cooling process of welding.
Hence, it is proposed that, by employing shielding gas during MIAB welding, there is a possiblity to eliminate the pores.However, in common with other forge welding techniques such as flash and friction, MIAB weld quality cannot be assessed by the non-destructive techniques of radiography. This is because it is possible to have thin layers of oxide or flattened inclusion at the weld line which are too small to detect but can give areas of low adhesion and hence weakened welds.