High Temperature Fatigue of Aged Heavy Section Austenitic Stainless Steels

Abstract

This work investigates two austenitic stainless steels, Sanicro 25 which is a candidate for high temperature heavy section components of future power plants and Esshete 1250 which is used as a reference material. The alloys were subjected to out-of-phase (OP) thermomechanical fatigue (TMF) testing under strain-control in the temperature range of 100 ∘C to 650 ∘C. Both unaged and aged (650 ∘C, 3000 h) TMF specimens were tested to simulate service degradation resulting from long-term usage. The scanning electron microscopy methods electron backscatter diffraction (EBSD) and energy dispersive spectroscopy (EDS) were used to analyse and discuss active failure and deformation mechanisms. The Sanicro 25 results show that the aged specimens suffered increased plastic straining and shorter TMF-life compared to the unaged specimens. The difference in TMF-life of the two test conditions was attributed to an accelerated microstructural evolution that provided decreased the effectiveness for impeding dislocation motion. Ageing did not affect the OP-TMF life of the reference material, Esshete 1250. However, the structural stability and its resistance for cyclic deformation was greatly reduced due to coarsening and cracking of the strengthening niobium carbide precipitates. Sanicro 25 showed the higher structural stability during OP-TMF testing compare with the reference material.

Sustainable New Technology for the Improvement of Metallic Materials for Future Energy Applications

“…Other challenges that metallic materials face in biomass energy are abrasive wear [92], material degradation due to small dusty particles [93], and thermomechanical fatigue (high-temperature fatigue) [94][95][96].…”

Investigation on the Reliability of an Ablation Thermal Protection Coating with Adjustable Thickness under Aerothermal–Vibration Coupling Environment

“…[ 1,2 ] Complex thermal–mechanical coupling loads can significantly reduce the strength of the metal structure on the supersonic vehicles, thus increasing the risk of safety incidents. [ 3–6 ] Epoxy resin‐based ablation thermal protection coatings (ATPCs), consuming a large amount of thermal load via the pyrolysis reaction, have attracted increasing attention due to their advantages of high efficiency, low cost, and good versatility to complex structures. [ 7–9 ] However, the primary challenging issue associated with the fast ablation rate, poor toughness, and easy cracking severely restricts the improvement in thermal protection performance of ATPCs.…”