Study on the out-of-plane deformation of the Portevin–Le Chatelier band by using digital shearography

•The out-of-plane displacement within the PLC band is firstly obtained.•The displacement gradient is greater in the front of the PLC band than in the rear.•There is a slight relative torsion around tensile axis when the PLC band appears.•The process of position changing of the PLC band is firstly presented.•The transition process of inclination direction of the PLC band is shown in detail.