Influence of Cu Addition and Austempering Treatment on Mechanical Properties and Microstructure of GGG 50

B. Kilinc and S. Kirtay Istanbul University, Engineering Faculty, Department of Metallurgical and Materials Eng., 34320 Avcilar, Istanbul, Turkey

Full Text PDF

An investigation was carried out to examine the effect of austempering on the microstructure and mechanical properties of nodular cast iron GGG 50 (DIN EN 1563) alloyed with different amount of copper. Optical, scanning electron microscopy and energy dispersive spectroscopy analyses were performed for microstructural characterization. In addition, hardness and tensile tests were carried out for mechanical properties determination. Specimens were austenitized at 900°C for an hour, then austempered for an hour at 330°C in salt bath and cooled at a room temperature in air. The results indicated that the addition of Cu to GGG 50 encouraged pearlite formation in the matrix structure. In addition, with the austempering heat treatment, the structure was transformed from ferrite + pearlite into ausferrite and retain austenite. Furthermore, for the alloy with 2 wt% Cu addition, it was noted that the graphite nodules diverged from sphericity and Cu was concentrated around the graphite. After austempering, mechanical properties were significantly improved and the highest mechanical properties were found at 1.5 wt% Cu.

DOI: 10.12693/APhysPolA.132.461 topics: austempering, cast iron, mechanical properties, microstructure