In recent years, the mechanical behavior during stress relaxation of metallic materials has generated considerable interest owing to its contribution to formability improvement. Stress relaxation tests in the past had mainly used to obtain the activation volume, strain rate sensitivity, and other rate-dependent parameters during plastic deformation. The non-constant mobile dislocation density during relaxation was ignored in the earlier studies assuming its negligible influence. However, subsequent studies have established the importance of considering the evolution of mobile dislocation density during relaxation. To elucidate the phenomena, uniaxial tensile tests with single and repeated relaxation steps were performed under different relaxation times and pre-strain. The reloading yielding behavior post relaxation and strain rate sensitivity estimated using stress relaxation test were investigated using phenomenological stress relaxation model. The reloading yielding post relaxation studied indicated that the possible mechanism is velocity dependent and not strain aging as assumed earlier. Further, a new methodology is proposed to eliminate the effect of mobile dislocation density when estimating strain rate sensitivity from stress relaxation tests. Both the above outcome is novel and has not been reported earlier.