Effect of Equal Channel Angular Pressing (ECAP) on Wear Behavior of Al-7075 Alloy

AbstractEqual-channel angular pressing (ECAP) is an effective fabrication process for obtaining ultrafine grained materials. In order to investigate the effect of grain refinement during ECAP on wear properties of Al 7075 alloy, the specimens were pressed up to four passes by route BC at room temperature. Followed by ECAP, dry sliding wear tests have been conducted using a pin-on-disk machine under different loads of 10, 20 and 30N at a constant sliding speed of 0.23 ms-1. Microstructural observations were undertaken using transmission electron microscopy (TEM) and the surface of worn specimens was investigated by scanning electron microscopy (SEM). The effect of load and ECAP process on the mass loss, have been explained with respect to microstructure and wear mechanism. Comparison of wear resistance of specimens shows that by using ECAP process, wear resistance of the specimens increases considerably due to the formation of very fine grains during ECAP

Effect of equal channel angular pressing on aging treatment of Al-7075 alloy

The effect of aging treatment on microstructure and mechanical properties of equal channel angular pressed Al-7075 alloy was examined. Commercial Al-7075 alloy in the solid solution heat-treated condition was processed by equal channel angular pressing through route BC at both the room temperature and 120 °C. Only three passes of equal channel angular pressing was possible due to the low ductility of the alloy at both temperatures. Followed by equal channel angular pressing, the specimens have been aged at 120 °C for different aging times. Mechanical properties were measured by Vickers microhardness and tensile tests and microstructural observations were undertaken using transmission electron microscopy, X-ray diffractometer as well as optical microscopy. Microstructural investigations showed that ultrafine-grained materials with grain size in the range of 200–350 nm and 300–500 nm could be obtained after three passes of equal channel angular pressing at room temperature and 120 °C, respectively. Equal channel angular pressing of solid solution heat-treated Al-7075 alloy accelerates precipitation rate and subsequently leads to a significant decrease in aging time to attain maximum mechanical properties. Furthermore, it is possible to achieve maximum mechanical properties during equal channel angular pressing at 120 °C as a result of dynamic aging and formation of small ɳ´ phase

Effect of ECAP temperature on microstructure and mechanical properties of Al–Zn–Mg–Cu alloy

The effect of equal channel angular pressing (ECAP) at different temperatures (room temperature, 120, 150 and 180 °C) on microstructure and mechanical properties of Al-7075 solid solution alloy was investigated. Microstructure of the specimens was examined using orientation imaging microscopy, transmission electron microscopy as well as X-ray diffractometer, and mechanical properties were measured by Vickers microhardness and tensile tests. Microstructural investigations showed that after 3 or 4 passes of ECAP, fine grains with average grain sizes in range of 300–1000 nm could be obtained at different ECAP temperatures. Increasing ECAP temperature from 120 to 180 °C caused a decrease in mechanical properties as a result of increasing grains and precipitates sizes, decreasing fraction of high angle boundaries and also transformation of η′ into η phase, while increasing ECAP temperature from RT to 120 °C leads to an increase in mechanical properties due to the formation of small η′ precipitates. So it can be concluded that ECAP process at 120 °C is the optimum process for attaining maximum mechanical properties. Quantitative estimates of various strengthening mechanisms revealed that the improvement of mechanical properties was mainly attributed to grain refinement strengthening, precipitation strengthening and dislocation strengthening

An investigation into the effect of alloying elements on corrosion behavior of severely deformed Cu-Sn alloys by equal channel angular pressing

To overcome some possible deficiencies of pure copper, dilute alloying and employment of equal channel angular pressing seem the cost-effective solutions. In this work, dilute copper alloys with the tin amount of 0.18, 0.3, and 0.5 wt.% were obtained with continuous casting and subsequently, they were subjected to ECAP process up to four passes. It was shown that integrated treatment by dilute alloying and ECAP lead to 182% improvement of the corrosion resistance as compared to the as-received condition due to the grain refinement. Meanwhile, the alloying impact on current density is decreased with the ECAP process which may result from the changes at the distribution of Sn atoms in Cu. The difference in measured corrosion current density of unprocessed and ECAPed samples for the alloys Cu-0.3%Sn and Cu-0.5%Sn are 15% and 2%, respectively. The corrosion improvement by means of current density reduction due to the alloying before the ECAP process is about 45% while this value after the ECAP diminishes to 35%. Microstructure analysis showed that four passes of ECAP process cause the average grain size of the pure copper to less than 700 nm and the Cu-0.5%Sn to about 550 nm. Also, the HAGBs fraction of the ECAPed pure Cu is 74%, while the corresponding magnitude for the Cu-0.5%Sn is 78%. © 2019 Politechnika Wrocławsk