wing skin materials

[conscin]

Considering that Al 7475-T7351 plates have good fatigue and crack growth strength and higher fracture toughness than 2024-T351 and others 7XXX alloys, somebody knows why the majors aircraft makers does not use Al 7475-T7351??
Thanks

 

[debodine]

Without doing any research, my off the cuff guess would be cost.

 

[rb1957]

despite what is said of 7475 (high quality, premium selection) i don't think it's fatigue properties are as good as 2024. fracture toughness is a secondary importance on the wingskin, compared to crack growth, and i think it's here that 2xxx beats out 7xxx.

2xxx is my preferred choice for lower wing skins, 7xxx for stringers and spars and upper skins.

 

[KENAT]

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