The FSP was carried out on the 1050 Aluminum alloy as a base material with TiH2 as a blowing agent. I didn't use Al2O3. The holding temperature and holding time for the foaming process were 550 °C and 14 min respectively. After heat treatment, I didn't see any pore on the surface of the precursor. Should I carry out the microscopic observation to see the pores?
It should be noted that I deliberately considered foaming temperature under liquidus temperature of 1050 Aluminum alloy because I don't understand why in the other references the foaming temperature was above the liquidus temperature of base material while the purpose isn't melting of the base material.
It can be detected by scanning electron microscopy before and after heat treatment...
Better to try according to as given in the literature. Foam pores can be easily visible by naked eye. Increase holding time or change foaming agent.
The so-called wormhole defect is a typical flaw in FSW on different metals. This type of defect arises when the FSW tool travel speed is too high. The most used NDT methods for detecting such a defect are phase array ultrasonics and X-ray . Sometimes there is an open and visible discontinuity on the FSW weld surface which requires no extra detection, however if this discontinuity is beneath the weld surface then some NDT as above should be applied as well as eddy current and UV irradiated penetrating fluids . So if there are some surface pores then the weld should be NDTed for some hidden defects too.
Percentage of adding foaming agent to the base alloy and add the casting catalyst dying the process ,this will increase the viscosity of molten base which causes to increase the foam forming
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