Investigation of the Constitutive Model for Warm Stamping of 7075-T6 Aluminum Alloy Sheet

摘要

Warm stamping has potential application in processing 7075-T6 aluminum alloy for using the better formability of the alloy at elevated temperature. The constitutive model of 7075-T6 aluminum alloy at elevated temperature was investigated for the simulation of warm stamping. The uniaxial tensile tests on 7075-T6 aluminum alloy were conducted at elevated temperatures (ranging from 373 to 523 K) and different strain rates (ranging from 0.01 to 1 s~(-1)) by using a Gleeble-3500 simulator. Serials of continuous images of the specimens were taken by a general camera and Digital Image Correlation (DIC) method was adopted to obtain the strain fields during tensile tests. With the strain field data, the constitutive model 7075-T6 aluminum alloy was built, then the simulation works were done for the warm stamping with the constitutive model. Both the result of simulation and experimental works showed that the warm stamped part exhibited comprehensive property on smaller springback and higher final hardness when the optimal parameters are as following: the sheet was heated and holed for 10 minutes in a furnace preheated to 273 K, and then rapidly transferred onto a press where forming and quenching take place. Finally, the experimental result for warm stamped part showed that the springback angle was 4.61° and hardness was 180.6 HV.