Influence of Processing Parameters on Microstructural Evolution and Tensile Properties for 7075 Al Alloy Prepared by an ECAP-Based SIMA Process

Abstract

A modified strain-induced melt activation (SIMA) process consisting of homogenization, equal-channel angular pressing (ECAP) and subsequent heating to the semisolid temperatures was introduced to prepare the 7075 aluminum alloy with superior thixotropic behaviors. The effects of both the homogenization and the number of ECAP passes, as well as the isothermal temperatures on the microstructural evolution, were investigated. The results indicate that ideal microstructure wherein fine and globular solid grains surrounded by uniform liquid films can be achieved through ECAP deformationrecrystallization mechanism. Increasing the number of ECAP passes accelerates the recrystallization of strained grains, thus reducing the average grain size and improving the grain sphericity. Moreover, higher holding temperatures and prolonged soaking time can improve the growth of the solid grains. Two main coarsening mechanisms, viz. coalescence and Ostwald ripening, contribute to the growth of the solid grains simultaneously and independently. The tensile strength of the 7075 alloys after four-pass ECAP-based SIMA and T6 heat treatment is relatively lower than the as-received billet, while the elongation of SIMA processed samples is much higher than that of as-received ones. Increasing the number of ECAP passes improves the tensile strength for alloys with and without T6 treatment due to the fine grain strengthening mechanism.

Enhancement of impact toughness properties of Al 7075 alloy via double aging heat treatment

“…It was also observed that the precipitates grew with increasing second aging time. This can be explained by the Ostwald ripening, which has a more stable thermodynamic structure and small particles disappear [24,25]. As a result of coalescence and Ostwald ripening, spherical precipitates appear in the microstructures with some increase in average grain size (Fig.…”

Effects of B Addition on the Microstructure and Microhardness of Melt-Spun Al-7075 Alloy

“…Apart from these interesting properties; superior performance, design perspective, reasonable production costs and well-known manufacturing techniques reveal why the Al alloys are preferred more often than other metal alloys in the manufacturing sector [3]. Considering the above-mentioned properties of the aluminum alloys, 7000 series (Al-Zn-Mg-Cu) aluminum alloys are mostly known as the aluminum alloys with the excellent mechanical strength [4][5][6][7][8]. In addition to this advantage, the 7000 series aluminum alloys stand out with their properties such as good ductility [9,10], corrosion resistance [9][10][11][12] and weldability [7,10,13].…”

Deformation Characteristics and Constitutive Equations for the Semi-Solid Isothermal Compression of Cold Radial Forged 6063 Aluminium Alloy

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