Abstract

The aim of this research is to study the formation of intermetallic phases in a duplex stainless steel as a result of heat treatment at 800 °C for 30 min, 1 h, 3 h, 5 h, and 6 h. This was carried out using Optical Microscopy (OM), Scanning Electron Microscopy (SEM), and Elemental Analysis by Energy Dispersive X-ray Spectroscopy (EDS). The microstructural analysis revealed that the as-received sample has a ferrite (α) content of 52.05 ± 1.91 % and an austenite (γ) content of 47.95 ± 1.91 %. On the other hand, the samples subjected to heat treatment showed the presence of intermetallic phases such as the sigma phase (σ), chi phase (χ), and secondary austenite (γ2), resulting from the decomposition of ferrite through the eutectoid reaction α → σ + γ2, which occurs at α/γ or α/α interfaces. Additionally, as the treatment time increases, the amount of precipitated sigma phase increases, decreasing the ferritic phase fraction and increasing the austenitic fraction compared to the original amount. Thus, the α phase after 6 h of treatment presented an area fraction of 15.44% and the γ phase showed an increase up to 56.70% at 3 h, decreasing then to 46.92% at 6 h. Regarding the fraction of intermetallic phases, mainly the sigma phase, the results reported 37.64% at 6 h.