Studies on the Hot Forming and Cold-Die Quenching of AA6082 Tailor Welded Blanks

Abstract

An advanced forming process involving hot forming and cold-die quenching, also known as HFQ®, has been employed to form AA6082 tailor welded blanks (TWBs). The HFQ® process combines both forming and heat treatment in a single operation, whereby upon heating the TWB, it is stamped and held between cold tools to quench the component to room temperature. The material therefore undergoes temperature, strain rate or strain path changes during the operation. In this paper, a finite element model (FEM) was developed to investigate the formability and deformation characteristics of the TWBs under HFQ® conditions. Experimental results, i.e. strain distribution, were used to compare and validate the simulation results. A good agreement between the experiment and simulation has been achieved. The developed temperature, strain rate and strain path dependent forming limit prediction model has been implemented into FE simulation to capture the complicated failure features of the HFQ® formed TWBs. It is found from both experiment and simulation that the forming speed has important effects on the occurrence of failure position, where the failure mode for the 1.5-2 mm TWBs may change from localised circumferential necking to parallel weld necking.HFQ® is a registered trademark of Impression Technologies Ltd.

Experimental and numerical studies on mechanical properties of hot-stamped tailor welded AA7075-T6

“…Therefore, an important reason for the lower hardness in the FZ compared to the HAZ and BM may be due to the filler metal ER5356 as suggested by Salleh et al 33 The high hardness obtained in the HAZ means that the combination of the HS and AA operations can compensate for the detrimental welding effects and restore the mechanical properties of the welding zones. 26,34…”

Hot Sheet Metal Forming Strategies for High‐Strength Aluminum Alloys: A Review—Fundamentals and Applications

“…As described above, the SSSS condition can be achieved using a high cooling rate after solution heat treatment; in the hot stamping process, this is obtained using cooled forming tools, as reported in other studies. [159,[192][193][194] The cooling rate over a temperature range of 400 to 290 °C is measured in another study [194] in the precipitation-hardenable aluminum alloys AA6082 and AA7075 using the novel HFQ hot stamping process. After solution heat treatment, the alloys are cooled with different cooling media, namely 1) water, 2) a water-aquatenside mixture (AQ-D) that allows a high cooling rate and lower thermal distortion than water quenching alone, and 3) cooled forming tools (Figure 28a,b).…”

Opportunities, Challenges, and Influencing Factors in the Forming of Preconditioned Semi‐Finished Products Made of EN AW‐6082 and ‐7075

“…The production of the W‐Temper condition is always based on solution heat treatment followed by quenching, but the specifications on time and temperature vary, depending on the alloy and the literature source. For EN AW‐6082, temperatures of 525–540 °C, [ 20 ] 530 ± 10 °C, [ 21 ] or 535 °C [ 22 ] are used, whereas 470–480 °C, [ 20 ] 465 ± 5 °C, [ 21 ] or 475–480 °C [ 23 ] are used for EN AW‐7075. At these temperatures, the samples are solution annealed for 5 [ 5,24 ] or 10 [ 23 ] up to 30 min.…”