To certifying structures and the materials to be used under the high temperature operating conditions of the proposed ASTRI CSP plant, the mechanical properties of the principal candidate construction materials need to be characterised. These candidate materials are affected by the harsh conditions associated with the various sub systems of the power plant, where the principal objectives of this characterisation work include:
- Microstructural effects of long-term thermal cycling
- Dissimilar metal joining
- Formation of alloy depletion layer
- The effect on deleterious phase formation
- Effect of alloy depletion layer on fatigue
- Transient creep-fatigue behaviour
Ultimately, the goal is to de-risk ASTRI’s new technologies by better understanding the failure mechanisms that are likely to occur in service and providing vital materials design data for the engineering design team.
Thermal Aging
To better understand the effect of thermal aging on the candidate alloys, work has begun to characterise the formation of sigma phase within stainless steels subjected to prolonged high-temperature conditions. Sigma phase within the ferrous alloys degrades the alloy leading to a reduction in its associated mechanical strength. Initially, the work will expose 316L Stainless Steel to temperatures between 650 oC and 850 oC for durations between 100 hrs and 1000 hrs. After exposure, the samples are analysed for sigma phase produced for a given exposure. The results are also validated using ThermoCalcTM software that predicts the equilibrium composition of an alloy for a prescribed set of environmental conditions.
Project Funded by the Australian Solar Thermal Research Institute.