Creep deformation is a major failure mechanism in turbine blades operating under high-temperature and high-stress conditions over extended periods. Traditional approaches to estimating the service life of turbine blades such as the Larson-Miller Parameter (LMP) method rely on simplified assumptions and offer only approximate predictions, which may not adequately reflect the complex time-dependent behavior of materials. In this study, a more accurate and physically realistic methodology is proposed using finite element (FE) analysis based on time-dependent plasticity to simulate creep in turbine blades. Three different constitutive models accounting for creep deformation are employed to evaluate their effectiveness in predicting the blade’s lifespan. The turbine blade is assumed to be composed of Inconel 738LC, a cast nickel-based superalloy widely used in aerospace and power generation applications due to its high-temperature strength and corrosion resistance. The simulation results are benchmarked against experimental creep data and compared to predictions obtained using the LMP method. The findings demonstrate that the proposed time-dependent plastic models provide a significantly improved prediction of creep life, showing a longer service duration compared to those estimated by conventional elastic stress analysis and the LMP approach. This modeling framework offers a more robust and accurate tool for the design and durability assessment of critical turbine components.