Microstructure and mechanical properties of a spray formed and extruded AA7050 recycled alloy

Abstract

This paper presents the results of the evaluation of the microstructure and mechanical properties of an aerospace alloy recycled from machining chips by spray forming. The machining chips are produced during the manufacturing of machined aircraft parts and represent a high percentage of the initial rolled plate weight. Basically, the idea that guides the development of this work translates into adding value to the use of aerospace alloy machining chips, since these are incorporated in the recycling chain of the casting industry, without adding value. For this purpose, the material AA7050 was collected from an airframe machining facility and spray formed using nitrogen as the atomizing gas at pressure of 6 bar. The deposit was then hot extruded at 425 °C with a 10:1 reduction. Subsequently, samples were solution heat treated (4 h at 420 °C and 8 h at 470 °C) and age hardened at three different conditions. For the best age hardening condition, the results of tensile tests at room temperature were 623 MPa tensile strength, 563 MPa yield strength, and 12% elongation. Comparing these results with the specification data for the AA7050 material, it is possible to conclude that the mechanical properties of the spray formed material, to same extent, exceeded the standard data.