数字剪切散斑干涉法研究铝合金中Portevin-Le Chatelier带的离面变形行为

Digital shearography investigation on the out-plane deformation of the Portevin-Le Chatelier bands

作为Portevin-Le Chatelier(PLC)带的重要特征之一,其离面变形仍缺乏实验研究.本文提出使用数字剪切散斑干涉法研究GB6061铝合金中PLC带的离面变形.通过图像相减得到的条纹图,实时观察了PLC带的几何形貌和传播过程,并获得了PLC带离面位移分布.在1/15 s内,PLC带的最大离面位移为245 nm,位置偏向于PLC带传播的前沿.在条纹图中,PLC带传播前沿的亮条纹始终较窄.此外,实验还观察到PLC带位置变更和倾角转向的演化过程.实验表明,数字剪切散斑干涉法具有高灵敏度和防震性,是研究PLC带离面变形简便有效的方法.

Digital shearography is proposed to study the out-plane deformation of the Portevin-Le Chatelier （PLC） band during tensile tests in an Al alloy. The geometrical shape and propagation of the PLC bands are visualized in real time through fringe pattern in subtracted images. In 1/15 s, the maximum out-plane displacement is 245 nm within the PLC band. The displacement distribution is asymmetric while in fringe pattern, the white fringe is narrower in the front of the PLC band than in the rear. In addition, the evolution processes of position shifting and inclination transition of the PLC bands are presented in detail.