Study on local zones constituting to band growth associated with inhomogeneous plastic deformation

Plastic instability associated with Lüders band deformation affects the surface quality of structural steel products during metal forming operations such as drawing. In this work band growth mechanism involved in Lüders deformation is studied in mild steel by analyzing deformation in two local zones within the Lüders band width namely effective width and active zone using digital image correlation, an imaging, noninvasive technique for strain mapping. Change in magnitude of these local zones in the load plateau and associated strain rate variations within these zones clearly revealed the irregular growth of these zones reflecting the irregularity involved in two stage Lüders band growth mechanism. •Effective width of Lüders band varies largely and active zone increases irregularly in the load plateau for a particular specimen thickness.•Two stage band growth mechanism involved in Lüders deformation is found to be irregular.•Peak strain rate always localizes in the effective width and varies in the active zone.