Influence of process parameters on localized corrosion of AA7075 alloy during the production of aeronautic components

Abstract

The 7xxx alloys are mainly used in high stress applications, such as aircrafts structural parts, due to their great mechanical properties and low density compared to steel. Depending on the intermetallics in the alloys, they may suffer pitting which reduces the materiaĺs fatigue life time. The objective of the study was to identify what factors during the manufacture of AA7075 alloy parts are significant and how they should be controlled to minimize the occurrence of corrosion. Three steps of the production cycle were considered, machining, deburring and liquid penetrant test. After the definition of the significant factors at each step separately, a design of experiment based on a fractional factorial type was built for the whole manufacture line. The response variable was the amount of corrosion obtained by image analysis. The most significant factors were found at the machining stage: state of the bench vice jaw material (device which holds the aluminum part at the CNC lathe) and chloride concentration in the cooling fluid.

Statistical Model for the Mechanical Properties of Al-Cu-Mg-Ag Alloys at High Temperatures

“…Several researchers made use of the technique in the process of investigating the significant factors in experiments [20][21][22]. A fractional factorial design reduces significantly the number of runs required, particularly in screening experiments where many factors are studied in order to decide the relative importance amongst them.…”

Corrosion Behavior of AA7075-T73 Aluminum Alloy During Machining of Aeronautical Components

“…AA7075 aluminum alloy is a high strength precipitationhardenable alloy used to manufacture aircraft parts such as wings structures and hydraulics components due to its high strength-to-density ratio [1][2][3][4] . The higher mechanical resistance of this alloy is achieved by alloying with elements such as Cu, Zn, Cr, Mg, [1][2][5][6][7] .…”

“…AA7075 aluminum alloy is a high strength precipitationhardenable alloy used to manufacture aircraft parts such as wings structures and hydraulics components due to its high strength-to-density ratio [1][2][3][4] . The higher mechanical resistance of this alloy is achieved by alloying with elements such as Cu, Zn, Cr, Mg, [1][2][5][6][7] . Intermetallic phases containing Fe and Si, such as Al 7 Cu 2 Fe, Al 23 CuFe 4 and Mg 2 Si are commonly found in this alloy as inclusions and may have a deleterious effect on fatigue resistance [8][9] .…”

“…The manufacture of AA7075-T73 parts for aeronautical applications is composed of the following steps [1][2] :…”

Influence of Interfacial Stress Produced by MAO on Electrochemical Corrosion and Stress Corrosion Cracking Behavior in 7075 Aluminum Alloy

“…Al-Zn-Mg-Cu alloys are widely used in aerospace industry, military and automotive fields due to their excellent properties, such as low density, high specific strength and stiffness. [1][2][3][4] However, they are particularly vulnerable to stress corrosion cracking (SCC) in humid environment, which seriously restricts their large-scale application. 5,6 One strategy to reduce SCC of Al-Zn-Mg-Cu alloy is heat treatment (for example, T73), but this will inevitably sacrifice some strength.…”