Mechanical Behaviour and Springback Study of an Aluminium Alloy in Warm Forming Conditions

Abstract

This study deals with the mechanical behaviour and material modelling of an AA5754-O alloy at elevated temperature. Experimental shear tests were performed from room temperature up to 200• C, and the material behaviour has been identified with both shear and tensile tests, as a function of temperature. To analyse the influence of temperature during forming over springback, a split-ring test is used. Experimental results are obtained and compared to numerical simulations performed with the finite element in-house code DD3IMP. The numerical process of ring splitting is performed with the in-house code DD3TRIM. The main observed data are force-displacement curves of the punch during forming, cup thickness at the end of forming, and ring gap after splitting. It is shown that all these parameters are strongly dependent on the forming temperature. A correlation is obtained between experimental data and numerical simulation for the evolution of punch force and opening after springback as a function of temperature. The distribution of the tangential stress in the cup wall is the main factor influencing the springback mechanism in warm forming condition.

Springback analysis of AA5754 after hot stamping: experiments and FE modelling

“…Figure 11 shows that punch speed also played a dominant role in springback; as punch speed was increased, springback angles θ A and θ B were significantly decreased for the hot die/ punch forming condition for T blank = 250°C. The punch speed investigated in this study was much faster than previous studies (≥75 mm/s compared with 0.5-1 mm/s) [12,17]. In the case of angle θ A , it was found that it decreased by 55.9 % from 7.9°at 75 mm/s to 3.5°at 300 mm/s.…”

“…This technology has been studied for many years [4,12], and it was found that the formability of aluminium alloys can be enhanced considerably to a level equivalent to that of mild steel, with a moderate increase in the forming temperature to the range of 150-350°C. To enhance formability, warm forming processes are usually conducted under isothermal conditions and thus the forming tools are also heated up to a temperature ranging from 150 to 350°C.…”

“…Moon et al [16] demonstrated that the combination of a hot die (200°C), cold punch (−10°C) and low punch speed (1 mm/s) could reduce springback by up to 20 %. Laurent et al [12] studied the mechanical behaviour and springback of AA5754-O under warm forming conditions using cup drawing tests. They reported that the tangential stress in the cup wall was the main factor affecting springback.…”

AA 5754-O ALAŞIMININ ILIK DERİN ÇEKİLMESİ ÜZERİNE KALIP YÜZEY AÇISI ve BASKI PLAKASI KUVVETİNİN ETKİSİNİN DENEYSEL ARAŞTIRILMASI

“…Sıcaklık artışının bir diğer avantajı ise şekillendirme sırasında deformasyondan kaynaklı kap duvarlarındaki gerilmeleri azaltmasıdır. Geri yaylanma sac metal şekillendirmedeki önemli kusurlardan biridir [17]. Bu gerilme durumu kaplarda geri yaylanmalara sebep olur.…”

Effect of heat treatment conditions on stamping deformation and springback of 6061 aluminum alloy sheets

“…Kim H S and Koç M [16] found that the dimensional accuracy of springback could be improved by U-shape warm forming of AA 5754-O aluminum alloy under higher blank holder force (BHF), which could be interpreted as the uniform distribution of stress in the thickness direction when BHF was high. Grèze R and Laurent H [17,18] investigated the springback of AA5754-O aluminum alloy by a split-ring test in warm forming conditions. It was found that the springback amount decreased by 67% at 200°C compared with room temperature.…”