An experimental study and in-situ analysis of cross-loading of a micro-alloyed steel

This experimental study investigates the effects of cross-loading on ferritic, single phased, micro-alloyed HC340LAD steel. A serie of experiments were conducted on both virgin and pre-formed sheet material. Tensile tests were carried out on the initial and pre-formed materials to assess the impact on mechanical properties such as yield strength and fracture elongation. To evaluate the onset of yielding, the thermoelastic effect was used. In-synchrotron X-ray diffraction was employed to examine the elastic-plastic transition of different lattice planes and to analyse dislocation density in greater detail. This study provides valuable insights into the material's behaviour following an abrupt change in loading direction. Cross-loading resulting in a notable reduction of the yiled strength, as determined by temperature-based methods, and a decrease in dislocation density at the start of the test. A significant reduction in fracture elongation was also observed. These findings can aid in validation and enhancement of theorical models and crystal plasticity models based on dislocations.