Abstract
Incoloy A-286 is a Fe-Ni based superalloy and it is widely used in gas turbine industry, jet engines and other applications. Although A-286 has a long service history, the fabrication of A-286 is not without any challenges. The hot deformation property for this alloy is highly sensitive to its composition, especially the content of impurity such as sulfur (S). In present study, a batch of A-286 has suffered from cracking issue during rolling process at high temperature and detailed examinations have revealed that phenomena of liquation of Ti-rich phase induced by eutectic reaction with S appeared at grain boundary and caused intergranular fracture. To improve the hot deformation behaviors of A-286, alloy design has been performed with the minor addition of magnesium (Mg). Furthermore, its combined effect with manganese (Mn) has been examined. Experiments include tensile tests at 1050oC and 1175oC, cyclic oxidation at 900oC, detailed microstructure/fracture surfaces observations and composition analysis by OM, SEM-EDS, TEM-EDS, Auger, and EPMA. In conclusion, Mg addition can eliminate the phenomena of Ti-rich phase liquation, the high temperature deformation behaviours of A-286 can then be improved.