A Comparative Study on Tensile and Fracture Behavior of Al-Mg Alloy Processed Through Cryorolling and Cryo Groove Rolling

摘要

In the present work, Al-Mg alloy (AA 5052) was subjected to cryorolling followed by post-deformation annealing, in order to investigate its effect on tensile and fracture behavior. The solution-treated Al alloys were cryorolled (CR) and cryo groove rolled to different true strains. The microstructure of the samples (deformed and post-annealed) was characterized by optical microscopy, x-ray diffraction, and TEM to substantiate the mechanisms of grain refinement and its influence on tensile and fracture properties. Fractography of the tensile as well as three-point bending test samples was carried out using a scanning electron microscope (SEM) to reveal the fracture mode. The deformed samples (90% thickness reduction) exhibit significant improvement in strength (291 MPa) and hardness (110 HV) in CR samples and 313 MPa and 122 HV in cryo groove rolled samples, which is due to high dislocation density and grain size reduction. Post-annealing of the deformed samples (90% thickness reduction) led to improvement in its ductility as well as fracture toughness. The cryo groove rolled samples and post-annealed samples have shown better fracture toughness (142 kJ/m2) as compared to cryo rolled samples (29 kJ/m2) due to the relativelylarger grain and dimples as observed from TEM and fractography studies.