Partha Sarathi De

Asymmetric Cyclic Behaviour of Fine- and Coarse-Grained Commercially Pure Copper and Aluminium

In the present study, uniaxial ratcheting behaviour of annealed copper and aluminium with two different grain sizes has been investigated. Engineering stress-control tests have been performed at various combinations of stress amplitudes and mean stresses. To account for grain size variation, stress amplitudes were selected keeping the constant ratio of equivalent stress amplitude and tensile strength. It is found that ratcheting life of fine- and coarse-grained copper and aluminium is inversely related to both stress amplitude and mean stress. However, the effect of stress amplitude on ratcheting life is more as compared to mean stress for both the FCC metals. It is also find out that the ratcheting life of fine-grained FCC metals is more compared to coarse-grained FCC metals. The ratcheting strain rate follows three stages irrespective of stress combination and grain size of both FCC metals. It is observed that for both the FCC metals, the average steady state ratcheting strain rate follows perfect power relationship with cycles to failure.

Ductile Tearing Resistance Indexing of Automotive Grade DP 590 Steel Sheets: EWF Testing Using DENT Specimens

The essential work of fracture (EWF) method has been explored for indexing the ductile tearing resistance of DP 590 automotive grade dual-phase steel sheet both in longitudinal (L-T) and transverse (T-L) orientations. The simplest possible test and analysis procedures have been adopted. The EWF method is found to be eminently suitable for routine quality control and product development purposes for such materials. Areas for further research for improving the experimental strategy are highlighted. For the investigated steel sheet, the estimated tearing resistance is found to be distinctly higher for the L-T orientation compared to the T-L orientation; the reason thereof merits further investigation.