Changes in precipitation and corrosion characteristics of 18/10Ti austenitic stainless steel exposed to prolonged annealing at 750–850 °C

This investigation deals with the analysis of intergranular acicular precipitations by X‐ray diffraction techniques and SEM. Results obtained during analysing acicular precipitate in 18/10Ti steel, isothermally annealed at 750–850 °C, can be summarised as follows: Intergranular needles are constituted by a complex phosphide of M 2 P type whose chemical composition can be written as (Ti,Cr,Fe,Ni) 2 P. Crystal growth direction of intergranular acicular M 2 P particles in austenite is 〈 100 〉 γ . The following orientation relationship was determined between the complex phosphide of M 2 P type and austenite: . Corrosion testing in boiling 65% HNO 3 revealed that there was a relationship between the occurrence of acicular precipitate and a reduction in corrosion rate to a level below 0.5 g m −2 h −1 .