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Monotonic tensile tests and uniaxial load-controlled tension–tension cyclic tests were performed on commercial purity (99.99%) molybdenum in the recrystallized state in the temperature interval spanning RT (25°C) to 500°C range. Cyclic deformation behavior was characterized by analyzing the ratcheting strain, cyclic hardening response, and fatigue life. The response of unrecrystallized and recrystallized Mo was compared at room temperature; the influence of test variables including mean stress, stress amplitude and R ratio on ratcheting strain in recrystallized Mo at room temperature was also examined. The magnitude and rate of ratcheting strain evolution with cycles appear to depend on both the mean stress and the stress amplitude. Microstructural evolution during cyclic loading was characterized by conducting interrupted tests at room temperature as well as at 400°C. Observations confirm dislocations cell …