The Effect of T6 Heat Treatment on 7075 Aluminum on its Hardness and Tensile Strength

Abstract

This study aimed to determine the effect of T6 heat treatment on 7075 aluminum on its hardness and tensile strength. The T6 heat treatment process was heating the test specimens in an oven at various temperatures of the solution heat treatment (SHT) of 350°C, 400°C, 450°C, and 500°C for 2 hours. This process was then followed by quenching for 45 minutes and an artificial aging process at temperature of 120°C for 48 hours. The tests carried out included: Vickers hardness test, tensile test using ASTM B557-84 standard, microstructure test, and XRD test. The test results showed that the hardness and tensile strength before T6 heat treatment were 59.1 VHN and 235.7 MPa, respectively. After the T6 heat treatment was carried out, the hardness results were 105.8, 87.3, 108.9, and 171 VHN and tensile strength of 318.3, 415, 571.7, and 618.3 MPa, respectively. These results indicated that highest hardness was found in the SHT temperature of 500°C, while the increase in tensile strength was found in the temperature of SHT 500°C. It can be obtained because the formation of precipitate after the artificial aging process was due the formation of Al2CuMg and MgZn2.

Effect of Aging Treatment on the Strength and Microstructure of 7075-Based Alloys Containing 2% Li and/or 0.12% Sc

“…The Al 7075-Sc alloy exhibited the highest microhardness value of 185 VHN when subjected to a single aging process for 24 h at 120 • C. This aging treatment matches the widely recognized T6 temper, which is known to render 7075 aluminum alloys very hard. The T6 heat treatment involves a solution heat treatment within the temperature range of 450-480 • C followed by aging at 120-185 • C. During artificial aging, precipitates such as Al 2 CuMg and MgZn 2 form, contributing to the increased hardness [27]. Due to Sc-Zr interaction leading to the formation of the complex compound (Al 3 (Sc, Zr, and Ti)), the effectiveness of both additives in terms of increasing the alloy hardness was compromised.…”

Formability, Mechanical and Chemical Properties Assessment for High Strength AA7075 Subjected to Annealing Heat Treatment

“…Since Al 7XXX series is a heat-treatable alloy, and in order to enhance the formability and ductility, and to stabilize the microstructure of the Al 7075 alloy, a proper and effective annealing treatment is required and very important [3,5,6]. Three different types of second phase particles, including (intermetallic particles made from elements like Zr, Cr, and Mn), constituents (Fe or Si impurities, or excessive amount of major elements), and strengthening precipitates (MgZn2) can be found in the microstructure of the AA 7075 [5,7]. When this alloy properly annealed, the microstructure may be stabilized, and thesecond-phasee precipitates may be released from the matrix.…”

“…It is very important to understand how the second phase particles effect the recrystallization of this alloy. Using second phase particles as a mean of regulating size and texture of the grains during thermo mechanical processing requires a full understanding of the influence of them on annealing behavior [7,8]. However, the deformation heterogeneities at large particles may be the spots at which the recrystallization may commence during the annealing of materials with high alloying content.…”