1、Air bending of AZ31 magnesium alloy in warm and hot forming conditions C. Bruni, A. Forcellese, F. Gabrielli, M. Simoncini Department of Mechanics, Polytechnic University of Marche, Via Brecce Bianche , Ancona , Italy,CONCLUSIONS In all the process conditions, the forming load increases in early ben
2、ding stage and then decreases during the final stage;For a given temperature, stroke and punch speed, springback decreases with decreasing punch radius; Springback decreases with increasing forming temperature, irrespective of the punch radius value, even though such effect is reduced with decreasin
3、g punch radius and becomes almost negligible for the smallest one investigated;,DISCUSSION The influence of the punch radius on springback; for a given temperature and punch speed, an increase in the springback ratio with decreasing R appears. The punch speed can be seen that the K value is almost i
4、nsensitive to v, even if a trend characterised by a slight decrease in springback with increasing punch speed. For a given temperature and punch radius, the volume fraction recrystallised increases with increasing punch speed.,RESULTS(CONT.) Punch speed effect on the microstructure of the bent speci
5、mens, R=4mm and T = 300 C: (a) v = 0.45 mm/s and (b) v = 4.5 mm/s.,RESULTS The springback ratio increases with increasing temperature and punch radius.,INTRODUCTION Overview and importance. The effect of the process parameters on springback of AZ31 magnesium alloy was investigated by performing air
6、bending tests under warm and hot forming conditions. Magnesium alloys have been emerging as potentially candidates for several applications, in particular for lightweight structural and functional parts in the aerospace, automotive and electronic industries.Objective. To date, the mechanical propert
7、ies of magnesium alloys were investigated by many researchers 115; however, no systematic study on the effect of the process parameters on springback, under warm and hot forming conditions, can be found.Reference1. F.-K. Chen, T.-B. Huang, C.-K. Chang, Deep drawing of square cups with magnesium allo
8、y AZ31 sheets, Int. J. Mach. Tools Manuf. 43 (2003) 15531559.,METHODS MaterialAZ31 magnesium alloy was supplied in form of 3mm thick sheets,50mmin length and 27mmin width. The chemical composition (in wt%) of the Mg alloy is the following: 3% Al, 1% Zn, 0.2% Mn and balance Mg.Experimental procedures
9、 V-punch and U-die bending experiments were carried out at different temperatures ranging from 100 to 400 C, with different values of punch speed (v = 0.45 and 4.5 mm/s). Three different V-punches, with a constant angle of 60 and nose radii (R) of 2, 4 and 6mm, were used in the bending trials.,Punch speed effect on the springback ratio,Influence of temperature on the loadpunch stroke curves (v = 0.45 mm/s and R = 6 mm).,
