Thermal Stabilization is a heat treatment process performed on chemically stabilized alloys (primarily Stainless Steel) to introduce certain carbides while avoiding others. During welding or other heating processes, sensitization occurs which precipitates chromium carbide at the Heat Affected Zone (HAZ) resulting in a reduced amount of chromium solution in the alloy.
Depletion occurs at the boundaries of the HAZ and this significantly reduces the grain boundary corrosion resistance. Thermal Stabilization involves heating the alloy to higher temperatures and maintaining the desired temperature for a set amount of time. This allows the alloy to begin to form other carbides (such as titanium or columbian carbides) for the chromium carbides to remain in solution within the alloy as those carbides hold preferentiality. This form of heat treatment is generally only done on alloys that are already chemically stabilized as titanium or columbian carbides generally do not hold preference over chromium carbides unless chemically stabilized.