This course aims to provide the audience an introduction to time dependent plastic deformation of materials (creep) especially at high homologous temperatures. The goal is for the audience to learn the rate controlling mechanisms of creep and their utility in predicting the remaining useful life of a structure. Other Parametric approaches such as Larson-Miller parameter, Theta-projection concept, Kachanov-Rabotnov model will also be introduced. The course will conclude by highlighting the importance of accounting for creep in development of technologically important materials such as titanium alloys and nickel based super alloys.
Week 1: Introduction to creep, importance of studying creep, Basics of plastic deformation; Characteristics of dislocations and their role in strengthening of materials, Effect of vacancies;
Week 2: Definition of creep, stages of creep; Introduction to creep curve and derivation of equations of creep; Factors influencing creep; Introduction to mechanisms of creep;
Week 3: Mechanisms of creep: Newtonian viscous creep mechanisms; Grain boundary sliding; Viscous creep; Power law creep; Power law breakdown; Rate controlling mechanisms (mechanisms in series and parallel); Creep constitutive equation (Bird-Mukherjee-Dorn equation);
Week 4: Deformation mechanism maps (Ashby maps; Mohamed-Langdon maps); Modeling the service life of materials/components, Larson-Miller parameter, θ-projection concept, Kachanov-Rabotnov model; Creep testing techniques; Development of creep resistant materials: Case studies from Titanium alloys and Nickel based superalloy