Kinetics and morphology of Lüders deformation in specimens with homogeneous structure and with a weld joint

The presented work focus on the investigation of the elastic-plastic transition in materials with a sharp yield point occurring through the formation and propagation of Lüders band. It has been found that the band nucleation and propagation rates in specimens with homogeneous structure are considerably different. The velocities of Lüders band fronts are correlated so that the total velocity of all moving fronts at any point of deformation is a constant value. As the rate of deformation increases, the Lüders band front velocity increases nonlinearly. If the material contains zones with high structural and phase inhomogeneity, Lüders bands nucleate along the boundaries of these zones. The kinetics and morphology of the Lüders band fronts within these zones are considerably different from those observed in other areas of specimen. It has also been found that the Lüders band front stops upon reaching the boundaries of the zones with structural and phase inhomogeneity. In this case, the front acts as a source of both individual and multiple bands.