In the present work an existing sensitization prediction model has incorporated data collected for several AA5xxx using long-term (18 months) constant temperature (40°C -70°C) exposure tests. Other samples were also exposed in thermal exposure ovens with cyclic temperatures (40°C -45°C and 50°C -70°C) to represent the heating cycles in service conditions. High resolution scanning electron microscopy images were captured to estimate beta phase growth. ASTM G67 mass loss tests were performed to evaluate the degree of sensitization. The effect on sensitization of different alloying compositions and processing parameters was investigated. Stress distribution along grain boundaries was evaluated by experiment and simulated using Molecular Dynamics Simulations (MDS).