Abstract
Heat-resistant steels with high chromium additions (≥5 weight percent) are critical for many high temperature energy and manufacturing applications, including heat exchangers, pistons for engines, and dies for metal working and casting. However, while high chromium additions increase oxidation resistance at elevated temperatures, they also compromise thermal conductivity, resulting in a metallurgical trade-off between these two important properties. Here we show that a microstructure with both higher thermal conductivity and improved oxidation resistance at elevated temperatures is achieved in a unique steel with only 1 weight percent chromium, thereby overcoming the long-standing metallurgical trade-off. This is accomplished through a tailored thermal treatment that produces a tempered martensitic matrix with low solute content and a fine dispersion of copper precipitates and molybdenum enriched carbides. A further discovery is that the resultant thermally grown oxide includes an iron-copper-manganese-enriched outer layer that provides high-temperature oxidation protection equivalent to heat-resistant steels with five times the chromium content and 25% lower thermal conductivity.
| Original language | English |
|---|---|
| Article number | 262 |
| Journal | Communications Materials |
| Volume | 6 |
| Issue number | 1 |
| DOIs | |
| State | Published - Dec 2025 |
Funding
Research was in part sponsored by the Powertrain Materials Core Program, under the Propulsion Materials Program in the US Department of Energy Vehicle Technologies Office. The information, data or work presented herein was conducted in part as an Advanced Vehicle Power Technology Alliance (AVPTA) ‘Extended Enterprise’ project funded by the US Army Ground Vehicle Systems Center (GVSC), US Department of Defense, Department of the Army. AVPTA is chartered under the auspices of the US Department of Energy/US Department of Defense Memorandum of Understanding titled ‘Concerning Cooperation in a Strategic Partnership to Enhance Energy Security’. The research and development work was performed at the Oak Ridge National Laboratory, which is managed by UT-Battelle LLC for the US Department of Energy under contract DE-AC05-00OR22725. APT research was supported by the Center for Nanophase Materials Sciences, which is a US Department of Energy Office of Science user facility at Oak Ridge National Laboratory. The authors acknowledge Cody Taylor for heat treatments, Kelsey Epps for tensile testing, Stephanie Curlin for thermal properties measurement, George Garner for oxidation testing, Philip Gray and Mark Robbins for graphics, James Burns for preparing and running APT samples, and Erica Heinrich for technical writing.