Hot Dip Aluminizing of 9Cr-1Mo Steels and their Heat Treatment
Coupons of 9Cr-1Mo steels of type SA 387 Grade 9 class 2 were hot dip aluminized using Al bath at a temperature of 700 °C for 30 seconds. The samples were further heat treated at 750 °C for durations of 1, 3 and 5 hours, respectively. The samples were characterized using X-ray diffractometry, scanning electron microscopy and energy dispersive spectroscopy. The investigation showed that as coated samples contain an aluminum top coat, a reaction layer and substrate material. Within the reaction layer, two distinct regions corresponding to Fe2Al5 and Fe4Al13 were identified. Chromium up to 2 at% was observed. After heat treatment Al coat was not existing. Two distinct layers, corresponding to a thick Fe2Al5 and a thin FeAl were observed at shorter heat treatment duration. Under longer heat treatment durations, multiple phases, namely, Fe2Al5, FeAl, Fe3Al and solid solution of Al in Fe were observed.
P. Ramesh Narayanan and S.V.S. Narayana Murty
J. Patel et al., "Hot Dip Aluminizing of 9Cr-1Mo Steels and their Heat Treatment", Materials Science Forum, Vols. 830-831, pp. 143-146, 2015