Influence of cryogenic treatment on microstructure and properties of 8011 aluminum alloy

Based on the analysis of the metallographic structure, fracture morphology and mechanical properties, the microstructures and mechanical properties of 8011 aluminum alloy were investigated under different cryogenic processing time. The results indicated that the tensile strength and the elongation increase with extend of the holding time, and reach a maximum value when the alloy is cryogenically treated for 48 h with the elongation increased from 3.0% to 5.9%. The hardness reaches a maximum value when the alloy is cryogenically treated for 30 min. By analyzing the fracture morphology, it can be found that the fracture belongs to the ductile fracture, and the dimple increases as the holding time is extended. When the alloy is cryogenically treated for 48 h, the dimple increases significantly and the plasticity is improved.