For metallurgists, heat treatment is typically thought to be a well-understood practice. As a common process, it is used in both industrial and academic settings to change aspects of final components such as the metallic structure, stress state, and the sizes and compositions of precipitates. Because heat treatment is commonly used, it is quite intriguing when we stumble upon something new or surprising about this process.
My research group at Carnegie Mellon University (CMU) recently found that heat treatment can be leveraged to control inclusions in stainless steel. In addition to an intentional change in the metallic structure, we found that heat treatment also creates an unintentional, substantial change in the oxide inclusions. The inclusions first form by the oxygen-scavenging role of manganese and silicon, which are alloyed into the steel.