Comparative tribological studies of duplex surface treated AISI 1045 steels fabricated by combinations of plasma nitriding and aluminizing

• AlN coating was applied on AISI 1045 steel via plasma nitriding and aluminizing.
• Aluminizing of pre-nitrided specimen provides the highest surface hardness.
• The lowest wear rate was obtained via aluminizing of pre-nitrided specimen.
• Wear mechanism of the modified layer consists of oxidative and spallung wear.

Duplex surface treatments via aluminizing and plasma nitriding were carried out on AISI 1045 steel. A number of work pieces were aluminized and subsequently plasma nitrided (Al–PN) and other work pieces were plasma nitrided and then aluminized (PN–Al). Aluminizing was carried out via pack process at 1123 K for 5 h and plasma nitriding was performed at 823 K for 5 h. The fabricated steels were characterized using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD) and microhardness testing. Tribological behaviors of the duplex treated AISI 1045 steels were examined against tungsten carbide pin using a pin-on-disc apparatus at room temperature. The PN–Al specimen showed higher surface hardness, lower wear rate and coefficient of friction than the Al–PN one. It was noticed from the worn surfaces that tribo-oxidation plays an important role in wear behavior of both specimens.