Comparation of anisotropy of pure aluminum,iron and titanium sheets
To clarify the influence of crystal structure on the plastic anisotropy(r-value)of sheet metal,three high-purity metallic materi-als 1A99 pure aluminium,YT01 pure iron and TA1 pure titanium with typical crystal structures were studied to investigate the r-value evo-lution laws based on digital image correlation techniques and third-order polynomial fitting method.The results show that in terms of ani-sotropy,pure aluminium is correlated with the sampling direction,which is due to the relationship between the sampling direction and the main slip system;pure titanium is isotropic,which is only related to the densely-arranged hexagonal structure;pure iron has no obvious regularity in between,which is not only related to the sampling direction,but also related to the BCC structure.In terms of r-value,the r-value of pure aluminium in different directions is less than 1,while the r-value of pure iron is slightly greater than 1,and the r-value of pure titanium is greater than 1.68,which indicates that pure titanium＞pure iron＞pure aluminium in terms of the resistance to thinning,which is consistent with the crystal structure.At the same time,all three have better thinning resistance when sampling at 90°,which is related to the fact that the sampling direction is the furthest away from the main slip system.Finally,in terms of r-value evolution,pure aluminium varies greatly in three directions,while pure iron increases firstly and then decreases,and pure titanium decreases firstly and then increases except for sampling at 0° where it is almost unchanged,and these complex phenomena may be related to the evolution of volume fractions and texture in the preferentially oriented tissues.
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