Correlation between grain structures and tensile properties of Al-Li alloys

The correlation of grain structures (texture and grain shape) of some Al-Li alloys to their yield strength (YS) and elongation was investigated from a new perspective. The investigated materials include 2195, 2A96, 2A55 and 2050 Al-Li alloy sheets with 2 mm in thickness and plates with 5 and 10 mm in thickness as well as different layers in 2297-T87 and 2050-T83 Al-Li alloy thick plates with 80-85 mm in thickness. Higher YS in general corresponds to higher average orientation factor M (M ) values, but there still exist some exceptions. As yielding occurs during tensile deformation, some grains just rotate, slip systems are not activated in all grains and the activated slip system number in different grains is also different. The M value calculation therefore should be corrected and normalized excluding the grains in which slip system is not activated and considering the easiest activated slip systems. Meanwhile, the grain shape also plays an important role in YS. Although almost full recrystallization occurs, the higher grain aspect ratio tends to enhance the YS because of less grain rotating and more activated slip systems. Furthermore, the total equivalent slip system number and grain shape affect the elongation in that higher total equivalent slip system number and lower grain aspect ratio correspond to larger elongation.