24/01/2022
Optimized Cr-steels for Creep Resistance Development
TECNALIA is in charge of the development of the optimized Cr-steels for creep resistance in ACHIEF work plan. Along with TRI, they work together to develop novel Cr-steel grades with improved 15% creep resistance. Moreover, these two partners will also aim to optimize the heat treatment conditions for an improved control of the microstructure and precipitates (carbides, Laves phase, etc.) during tempering.
Based on the alloys defined during the Computational modelling and artificial intelligence development, TECNALIA has casted 5 ingots of 30 kg at laboratory scale: four new Cr-steel grades plus the reference steel grade T115. The ingots have been forged and cut into several sets of samples:
- First set of samples to simulate and design the optimum processing route for improving creep resistance: Dilatometry + Characterization of microstructural evolution, critical temperatures, phase transformations, etc.
- Application of the optimum processing route/s designed on a second set of samples for processing at lab-scale.
Figure 1. Lab castings: 3 ingots have been forged to bars.
Additionally, the partners have carried out dilatometry tests in order to design the thermal treatments. The thermal treatments have been applied and characterized in order to select the best treatments to be applied to the samples for creep analysis.
Figure 2. Thermal Treatment equipment at Lab scale.
The next steps of this WP include microstructural and mechanical characterization of samples after lab-scale processing (OM, FESEM, XRD, Tensile (RT, T), Hardness, Corrosion, Short-time creep tests at 1 temperature and 3 different stress values.
Finally, the steel grade (composition and processing route) offering the best overall creep behaviour will be selected for fabrication at pilot scale at the end of 2022. Next, TRI will produce tubes with this steel grade and a final characterization will be carried out to assess if the objectives of this activity have been achieved.
