Investigating the Effects of Expansion Equal Channel Angular Extrusion (Exp-ECAE) on Dynamic Behavior of AA7075 Aluminum Alloy

Subject Areas : Mechanical Engineering

J.  Shahbazi Karami ¹ (University of Shahid Rajaee Teacher Training, Iran)
S.  Sepahi-Boroujeni ² (University of Bu-Ali Sina, Iran.)
Mohsen  Khodsetan ³ (School of Mechanical Engineering, College of Engineering, University of Tehran, Tehran, Iran. *Corresponding author)

Received: 2016-02-26 Accepted : 2016-06-08 Published : 2017-01-14

Keywords: Dynamic Behavior, Expansion Equal Channel Angular Extrusion, AA7075 Aluminum Alloy, Severe Plastic Deformation, Hopkinson Pressure Bar,

Abstract :

Expansion equal channel angular extrusion (Exp-ECAE) is a severe plastic deformation (SPD) operation for processing bulk materials. In the current study, AA7075 Al was SPD-processed by expansion equal channel angular extrusion (Ex-ECAE) at various temperatures and ram velocities. Then, using split Hopkinson pressure bar (SHPB), the severely deformed products were compressed at room temperature and strain rates of 0.1~3000 s-1. Both the strain rate sensitivity (SRS) and the apparent activation volume (AAV) were determined for all deformed samples. The results revealed that the Ex-ECAE operation has noticeably increased the SRS. The tensile strength at a strain rate of 3000 s-1 was 6 times increased by conducting Ex-ECAE at 100 °C and with a ram velocity of 7 mm/min. Ex-ECAE was also capable of considerably decreasing the AAV. The results showed the yield stress of both the Exp-ECAE and the annealed samples increased with increasing the strain rate. Also, the results showed that after the Exp-ECAE process, the AAV reached to 6.3 b3 from the initial values of 118.5 b3 in the annealed state.

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