Mechanical behavior model of stainless steel 304 H at high temperature

The purpose of this research is to determine the precipitation degree of sigma and chi phases and their effect on the mechanical behavior of stainless steel 304 H with more than 15 years of service. Material verification was carried out using portable equipment for Positive Materials' Identification, a replication study was carried out on the external face of the element studied to measure the degree of precipitation of the sigma and chi phase using optical microscopy and an image analyzer. It evidenced that depending of to increase the presence of intermetallic phases for impact tenacity decreases, transforming stainless steel 304 H into a fragile material, likewise, manufactured components of 304 H that operate at high temperatures with identical service time may have different degrees of precipitation of the sigma and chi phases along it. Finally, it is proposed based on the results of metallographic replicas, a model that allows to predict the impact tenacity of degraded 304H steel in order to define the acceptance or non-acceptance of component in service without requiring destructive tests.