Development of a Time-Temperature Transformation Diagram for Alloy 925

Incoloy† Alloy 925 (UNS N09925) was developed as an age-hardenable alloy for sour gas well applications to provide the drilling industry with a suitable alternative to high-Cr and -Mo alloys that must be cold worked to achieve high-strength levels. This paper describes the microstructures, mechanical properties, and stress corrosion cracking (SCC) data obtained on alloy 925 in the annealed and aged, as well as cold-worked and aged conditions. Characterization of the phases present after aging treatments was conducted by conventional metallography, scanning electron microscopy (SEM), and x-ray diffraction (XRD). Time-temperature transformation diagrams, based on the microstructural information and mechanical properties data obtained after various heat treatments, are also presented for this alloy.