Thick plate of an aluminium alloy having improved fatigue characteristics, and method for fabricating it

摘要

A plate (slab) of an aluminium alloy more than 2 inches thick having a mean logarithmic fatigue endurance of more than 100,000 cycles at a maximum stress amplitude of 35 Ksi at a frequency of 10 Hertz and at a stress ratio R = 0.1, measured on a test bar having a diameter of 1/2 inch and a parallel measured length of 2 inches and otherwise as defined herein, the density of micropores having a dimension greater than 80 μm at all locations on the centre plane (T/2) position of the finished plate, measured by means of optical microscopy (OM), being less than 0.025 micropores per cm2 in any plane perpendicular to the plate surface.