OČENÁŠEK Vladivoj SVÚM a.s.

Fatigue Properties of Hand Forgings from 7175 Aluminium Alloy

Aluminium alloy 7175 is one of the high strength heat treatable aluminium alloys. Forgings used in severe operational conditions, especially in aircraft industry, are made of it. It´s mechanical and fracture properties are excellent as well as the corrosion resistance in tempers T74 and/or T7452. The very low content of impurities Fe and Si contributes to a very good fatigue resistance. The level and scatter of fatigue properties depend not only on the chemical composition and heat treatment, but also on the forming way and the amount of deformation. In the case of die forgings, which are forged usually from extruded rods, the extent of deformation from cast to forged structure is high and the fatigue properties do not depend markedly on it. The present paper deals with the effect of deformation on fatigue properties of hand forgings that are forged from cast and homogenized billets. In this case, the amount and way of deformation can influence substantially the fatigue properties and their homogeneity and anisotropy as well.