Effect of cooling environment and welding speed on fatigue properties of friction stir welded Al-Mg-Cr alloy

The Al-Mg-Cr aluminium alloy shows high resistance against fatigue crack propagation. This alloy loses its properties in weld nugget and nearby region due to excessive heat generation during welding. To see the effect of heat input during welding, in present study, friction stir welding of this alloy was done at different speeds in three cooling environments i.e. natural air, water, and liquid nitrogen. Study outcomes show that fatigue crack growth rate (FCGR) is lower in case of water cooling while presence of oxides in weld nugget zone in case of liquid nitrogen cooling causes a significant increase in FCGR.