Effect of Warm Forming on Formability and Springback of Aluminum Alloy Brazing Sheet

Abstract

This paper investigates the effect of warm forming (up to 350°C) on the formability and springback behavior of AA3003/AA4045 brazing sheet (0.2 mm gauge) for two temper conditions: O- and H24-temper. The key objective is to utilize warm forming to form aggressive geometries and control the springback to improve the part flatness which enables the use of harder temper material with improved strength. Simulations and experiments are performed considering heated dies at several different temperatures up to 350 °C and the blanks are pre-heated in the dies. The geometry under study is referred as a surrogate heat-exchanger component (SHC) and contains complex features found on commercial automotive thermal management systems. An in-depth springback characterization was completed for a wide range of forming process parameters such as: temperature, punch load, sheet direction, and holding time. Numerical simulations were also performed to predict the springback behavior and were compared to the experiments. There were no clear results showing improvement in formability using the warm forming process. However, increased temperatures (above 250 °C) offered significant improvement in springback for the harder H24 material temper.