Study of the structural inhomogeneity of bimetal layers at the yield plateau stage

The paper studies the kinetics of Chernov–Lüders band propagation of bimetallic material on the yield plateau at the microscale level. The localization patterns of plastic deformation in the process of uniaxial tension are obtained by noncontact method of recording the fields of displacement vectors. Microstructure of the interfaces studied by atomic force microscopy showed that in the direction of the pearlite steel to the austenitic form there are structural components: the weakened zone of the ferrite layer; hardened section of the ferrite layer dark-pickling layer from the side of austenitic steel. Plastic deformation of a bimetal begins from the nucleation of the Lüders band on the boundaries of the bimetal on stress raisers with higher hardness due to the diffusion effect. In the main layer the Lüders band is limited to a pair of fronts moving in opposite directions along the bimetal axis with different velocities. The cladding layer does not suppress the formation of Lüders bands, leads to an increase in the propagation velocity of Lüders band fronts in the base layer and reduces the Lüders band propagation in all bimetal layers.