Bending Fatigue Behavior of 7075-Aluminum Alloy

Abstract

Light alloys are a very interesting challenge in order to have light components with high mechanical features. One of these is the 7075 aluminum alloy, which is commonly employed in aeronautic, automotive and maritime fields.On the other hand, the application of a PVD (Physical Vapor Deposition) coating can improve the hardness of the surface and the tribological properties of the component.The effectiveness of these coatings on the fatigue behavior of the sublayer material is not already clear. For this reason, bending tests on uncoated and coated specimens in air were performed in order to evaluate the S-N diagrams

Effects of thin hard film deposition on fatigue strength of AA7075-T6

“…Experimental results for AA7075-T6 specimens subjected to rotating bending loading 33 , 34 , 41–43 with two different possible regression models. The circles refer to the experimental results of the specimens without the DLC film, the squares refer to the samples with the film.…”

“…Assuming compression as the starting point, the crack opens and grows during the following traction. A new 33,34,[41][42][43] compression closes the micro crack again. This mechanism introduces the striations which can only be seen with a scanning electron microscope.…”

“…The material properties are shown in Table 1. 33 , 36 The specimens were prepared by polishing the surface with 600- to 1200-grit paper and diamond paste 3 micron, and cleaning with acetone. According to ISO 1143, 35 polishing was performed along the axis of the specimen.…”

“…The contribution of thin hard film deposition on strength of AA7075-T6 under cyclic loading is still under investigation. 31–34 For this reason, this paper describes the experimental campaign conducted on some samples without and with DLC film in an air environment with a rotating bending load. The data obtained for the two types of specimens within the range of 105– 107 cycles were analyzed with two regression models.…”

Finite Element Analysis and Experiments for Predicting Fatigue and Rolling Contact Fatigue Behavior of Spur Gears

“…Therefore, low temperature coatings should be preferred, particularly if deposited on light alloys, as confirmed in a study on the contribution of type of coating and deposition temperature on 7075-T6 aluminum alloy [8]. The deposition of DLC coatings has been found to globally reduce the fatigue strength of 7075-T6 aluminum alloy within the number of cycles range 200,000-10,000,000 [9][10][11][12]. Another study which testifies to the doubtful contribution of PVD coatings on fatigue strength, better RCF strength, is presented in [13], where a more uniform damage-load diagram was obtained for uncoated spur gears compared to the coated components.…”