Effect of temperature and punch speed on forming limit strains of AA5182 alloy in warm forming and improvement in failure prediction in finite element analysis

Abstract

Formability of AA5182-O aluminum alloy sheets in the warm working temperature range has been studied. Forming limit strains of sheets of two different thicknesses have been determined experimentally in different modes of deformation (biaxial tension, plane strain and tension-compression) by varying temperature and punch speed. A correlation has been established for plane strain intercept of the forming limit diagram (FLD 0) with temperature, punch speed and thickness from the experimental results. This correlation has been used to plot the forming limit diagrams for failure prediction in the finite element analysis of warm deep drawing of cylindrical cups. The effect of strain and strain rate on material flow behavior has been incorporated using a strain rate-sensitive power hardening law in which the strain hardening exponent and strain rate sensitivity index have been experimentally determined. The predictions from simulations have been validated by warm deep drawing experiments. Large improvement in accuracy of failure prediction has been observed using the FLDs plotted based on the developed correlation when compared to the existing method of calculating FLD 0 using only strain hardening coefficient and thickness. The results clearly indicate the importance of incorporating temperature and punch speed in failure prediction of Al alloys using FLDs in the warm working temperature range.

Formability of AA6061 alloy sheets in warm forming temperature range

“…In this case, the difference between the peak loads of biaxial and plane strain conditions is also very less, which can be observed in Figure 12(c). This observation also corroborates the negative slope observed on the RHS of the FLDs tested at 300 C as explained by Satish et al 14 But the punch displacement after reaching the peak load is higher in 100 mm width sample due to biaxiality of loading and, hence, the overall punch displacement at failure is higher in biaxial tension than in plane strain condition even though the slope on the RHS is negative. The summary of peak loads is given in Table 2.…”

“…Similar observations have been reported earlier also at elevated temperatures. In the case of AA5182+Mg alloy, it was observed 14 that the effect of deformation speed was significant at elevated temperatures. The limiting major strain in biaxial stretching has been found to be almost equal to that of plane strain condition at 300 ℃.…”

“…Similar observations have been reported earlier also at elevated temperatures. In the case of AA5182þMg alloy, it was observed 14 that the effect of deformation speed was significant at elevated temperatures. The limiting major strain in biaxial stretching has been found to be almost equal to that of plane strain condition at 300 C. Shao et al 4 observed that the difference in limiting major strain values between biaxial and plane strain conditions decreased with the increase in forming temperature (in the range 200-300 C) of AA5754 alloy at a punch speed of 75 mm/s.…”

Effect of process parameters on formability in two-point incremental forming-machining of planar and twisted AA5083 blades

“…The temperatures were chosen such that they were always below the recrystallisation temperature of the 5083-aluminium alloy. [13][14][15] The tool diameter levels were selected according to the tool holder limitations, and a full factorial experimental design was considered. The experimental output is the change in the wall angle during the spring-back (%) according to equation (1):…”

Experimental Analysis of Punch Speed Impact on Plastic Behaviour of Extruded Material

“…The mathematical modelling for process simulation has therefore become a major tool for analysis of metal forming processes. The majority of analysis in researches are based on finite elements method (Farhoumand & Ebrahimi, 2016;Raja Satish et al, 2017;Trzepiecinski et al, 2017). Modelling of plastic behaviour in extrusion process and influence of die angle on strain rate is described in (Tolcha, 2014) while researchers in (Marin et al,2013) analysed strain-stress relations in compressive forming process.…”