A modified AISI 310 steel family: Microstructure engineering for high-temperature load-bearing applications

Austenitic stainless steel AISI 310 is commonly used for load-bearing and high-temperature industrial applications due to its combination of low cost, high strength, and corrosion resistance. However, with the continuous search for productivity enhancement combined with the ever-growing present demands on sustainability, the performance of this legacy material may not be enough. Example applications where this is apparent is hot stamping furnace components for the automotive industry, where most of the maintenance down-time can be attributed to failure of load-bearing components inside and at the entrance of the furnace. Upon detailed experimental and computational investigation, a root-cause-of-failure has been identified as excessive precipitation of grain boundary carbides and σ phase formation near the surface, limiting the creep life and leading to crack initiation. In this study, alloy modification strategies to enhance creep performance and mitigate pre-mature failure have been identified based on literature data and thermodynamic calculations. The primary modification strategies involve stabilising M23C6 and MC carbides over σ phase, but also to incorporate some Laves phase for potential creep life enhancement. The modified alloys have been produced and evaluated with respect to as-cast microstructure and phase transformation temperatures, validating the microstructure predictions.