A critical evaluation of the processing of an aluminum 7075 alloy using a combination of ECAP and HPT

作者：Sabbaghianrad Shima; Langdon Terence G^*

来源：Materials Science and Engineering A-Structural Materials Properties Microstructure and Processing, 2014, 596: 52-58.

DOI：10.1016/j.msea.2013.12.034

• Equal-channel angular pressing
• High-pressure torsion
• Microhardness
• Superplasticity
• Ultrafine grains

Experiments were conducted on a commercial Al-7075 alloy by processing by ECAP for 4 passes and then processing by HPT for up to a maximum of 20 turns. Measurements show that the grains were refined to similar to 680 nm after ECAP and to similar to 310 nm in the center of the disk after ECAP+HPT. Tensile testing at a temperature of 623 K revealed lower flow stresses and higher elongations to failure after processing by ECAP+HPT. Thus, the alloy was not superplastic after processing by ECAP but superplasticity was achieved with elongations up to similar to 800% after processing by ECAP+HPT. By plotting the Vickers microhardness against equivalent strain, it is shown that the hardness saturates at Hv approximate to 250 after ECAP+HPT. This saturation hardness is higher than the value of Hv 230 recorded after processing by HPT without a preceding step of ECAP. The results demonstrate that processing by ECAP + HPT produces higher hardness and greater grain refinement than processing only by HPT.

• 出版日期2014-2-24