Notch strength and stress concentration sensitivity of alloy 2090 with various cerium contents

The tensile strength of notch specimens has been investigated for alloy 2090 sheets with various Ce contents. The notch strength (sigma(N)) has been quantitatively analyzed. By comparison with Ce-free alloy, sigma(N) of Ce-containing alloy sheets exhibits an insignificantly change. The statistical estimation shows that sigma(N) evaluated from the theoretical expression is in better agreement with the test data. Accordingly, the strength of notched specimens can be conveniently predicted by means of the conventional tensile properties of smooth specimens. The notch insensitivity factor (K-N) has been derived for the alloy 2090 sheets with various Ce contents. K-N can be applied to assess the stress concentration sensitivity to structural notches in practical structures by comparison with the theoretical stress concentration factor (K-t). Increasing in Ce content in the alloy 2090 sheets can slightly enhances K-N or reduces the stress concentration sensitivity. However, Ce microalloying can not still essentially decrease the stress concentration sensitivity of the alloy 2090 sheets because the ductility can not be improved to a greater degree only by adding Ce element. Therefore, high stress concentration sensitivity may be a potential obstruction to the practical application of high-strength Al-Li based alloys in primary aircraft structures containing structural notches. (C) 2000 Kluwer Academic Publishers.