A D V A N C E D M A T E R I A L S & P R O C E S S E S | J A N U A R Y / F E B R U A R Y 2 0 2 3 3 2 Modern engineering applications require components to feature reliable mechanical and corrosion properties, manufacturability, and durability both at the fabrication stage and during long-term exposure to service environments. Mechanical and corrosion properties are determined by the material’s chemical and phase compositions. To a large extent, chemical composition determines the phases present in a material, but the phase composition is dependent on themanufacturing and heat treatment processes used to fabricate the components. For example, the rolling process can lead to formation of martensite at or near surface regions in austenitic stainless steels due to the presence of extensive deformation. Similarly, in precipitation hardening steels, martensite may revert back to austenite during aging, resulting in significant changes to the material’s mechanical properties[1]. Thus, from a design standpoint, understanding the phase composition of a material is critical to understanding the material’s behavior in the application as well as during the fabrication stage. Phase analysis has always played a critical role in both research and development as well as industrial production environments. However, while there is some overlap between these two settings, they each have different requirements and thus different techniques are generally used. Phase analysis can be subcategorized into qualitative and quantitative analysis. PHASE ANALYSIS PRIMER: HOW TO SELECT THE RIGHT ANALYTICAL TECHNIQUE Knowing the advantages and disadvantages of various analysis methods can help determine the best approach for the task at hand. Rajan Bhambroo,* Tenneco Inc., Plymouth, Michigan *Member of ASM International Fig. 1 — XRD spectra of 17-4 PH stainless steel after heat treatment at 620°C for two hours.