Line Analysis of Changes in the Deformation Zone During Lüders Band Propagation

Abstract

In order to determine the Lüders band propagation along the deformation zone length and width as affected by the force action direction, a detailed line analysis is performed by applying thermography and digital image correlation (DIC) during static tensile test at different test positions. The test is stopped at the point when the Lüders band propagation reached its middle to analyse temperature changes and deformations occurring in front of, on and behind the Lüders band front. Line analysis of the test samples confirmed that there are changes in the distribution of temperature and deformations. Across the width of the test sample, there are oscillations and differences in the distribution of temperature changes in the deformation zone. However, the same analysis showed that there are no differences in the change of deformations across the width of the test sample, except in the zone behind the Lüders band front where the Lüders band propagated. The influence of microstructure, i.e. the different dislocation density and the interaction of dislocations with fine precipitates, proved to be the cause of change in temperature and deformations measured at the moment when the Lüders band propagation reached its middle.

Keywords

• digital image correlation (DIC)
• line analysis
• Lüders band propagation
• niobium microalloyed steel
• thermography