Characterization and simulation of AA7075 hot stamping with subsequent die quenching for automotive structural applications

Abstract

Accurate modelling of the hot stamping forming process is necessary to achieve automotive structural parts that are both lighter for a lower environmental impact and safer in case of collisions. To comply with new environmental norms, some car manufacturers are attempting to replace high strength steel by high grade aluminium. The use of age hardenable aluminium alloys such as AA7075 present both new opportunities and challenges. Although a weight reduction of 20% is expected by this research program, the forming parameters window for parts made of aluminium alloys is much narrower than for their steel counterparts. The objective of this project is to better understand the process of hot stamping and quenching of AA7075. This, in turn, should allow a first iteration of tooling to be developed for the process. The scope of this work is limited to the general mechanical behaviour and does not include a damage model, which would be required to ensure the process’ success with a given set of parameters. In this work, it was found necessary to characterize the material used and other important process parameters such as interfacial heat transfer coefficients. This is done with material laws and models available in commercial finite element software, with the goal of being able to export the required data into a usable package for designers. An experimental tooling set was available before the end of this project, enabling a comparison of the numerical model with experimental results. Following this, it was possible to acquire a new understanding of the current failure modes and suggest improvements to the process. These improvements have confirmed the viability of the hot stamping and quenching with AA7075.

Date	23 Nov 2018
Original language	American English
Awarding Institution	École de technologie supérieure
Supervisor	Tan Pham (Supervisor) & Guillaume D’Amours (Co-supervisor)