Comparative study of quenched and austempered ductile cast irons

This work aims to evaluate the mechanical properties of three different materials, relating the tests results with the metallurgical features of the samples. The first and the second material were an austempered ductile cast iron (austempering temperatures of 260 and 3000C, respectively). The third material was a quenched and tempered ductile cast iron. Impact, tension and hardness tests were employed in the mechanical characterization of the materials. In the metallurgical characterization, optical microscopy and image analysis were employed. It was observed that in the impact tests, the austempered ductile iron in the temperature range of 3000C was the material with higher toughness. In this material, low hardness allied to the high retained austenite level (21%), were the main factors acting in the higher impact resistance of the 3000C austempered cast iron. Key words: ADI, mechanical properties, retained austenite.