Numerical and experimental investigation of low cycle fatigue behaviour in P91 steel

Fatigue influences steel structure and material properties and thus significantly influences degradation mechanism and lifetime of steel. The determination of fatigue curves is expensive, time consuming, difficult to implement the experiment, especially in reactor environment (high or low temperatures, acid or alkaline environments, etc.). Therefore finite element method can be helpful for material investigation to evaluate the behaviour of steel specimen during fatigue. The aim of this work is to propose a numerical tool able to compute low cycle fatigue and developing a finite element (FE) model for investigation of fatigue behaviour. The numerical simulation can be used to determine some points for construction of fatigue curve and to understand the mechanics of fatigue mechanism in more detail. In order to validate the model and to calibrate the model parameters, the experimental investigation of steel P91 LCF at 550 degrees C in strain control was carried out. P91 strain controlled high temperature low cycle fatigue tests were carried out and numerical investigations were performed using finite element code Caste3M. The plastic model with isotropic stress hardening was chosen for the description of material. As a result, the stress vs. strain hysteresis loops and stress vs. number of cycles curves at different loading were obtained. The. numerical simulation results were compared with the experimental tests.