Experimental investigation of tensile properties and anisotropy of 1420, 8090 and 2060 Al-Li alloys sheet undergoing different strain rates and fibre orientation: a comparative study

Al-Li alloys have gained great attention for military, aerospace, and commercial applications because of their outstanding properties compared to commercial Al alloys. However, the tensile properties of former Al-Li alloys cannot fulfil most of the design and manufacturing characteristics because of their poor formability, and anisotropy in tensile properties. Therefore, the third generation of Al-Li alloys was developed to overcome the shortcoming of the former Al-Li alloys. The sensitivity of tensile properties and anisotropy behavior of Al-Li alloys to fibre orientation (sample orientation) and strain rate is vitally important from the aspects of formability improvements and developing material models for formability prediction. Therefore, this paper aims at investigating the influence of sample orientation and strain rates on the tensile properties and anisotropy behavior of Al-Li alloys sheet through quasi-static and dynamic uniaxial tensile tests. AA1420 and AA8090 sheets were selected from first and second generations of Al-Li alloys respectively because of their outstanding properties. Moreover, AA2060 is a new third generation Al-Li alloy launched at 2011 by Alcao Inc. The results showed that AA2060 alloy offers superior tensile properties compared with former Al-Li alloys, notably along the rolling direction and at high rates of deformation. For instance, the elongation to fracture of AA2060 was increased to 21.9 % at a strain rate of 2000 s-1. However, it's formability at room temperature and quasi-static strain rate is very poor. Additionally, AA2060 is still suffering from anisotropic tensile properties, but the degree of anisotropy in less than the former Al-Li alloy. It is concluded that the quasi-static and dynamic tensile properties and formability for Al-Li alloy sheets show a dependable tendency in reference to sample orientation and don't display the constant trend with the increasing of the strain rate.