Influence of Rapid Cooling Rate and Homogenization Temperature on the Ferrite Content and Microstructures of CD3MWCuN Castings

The influence of homogenization temperature and rapid cooling rate on the ferrite content and microstructures of CD3MWCuN was investigated using BSE-SEM images. For these experiments CD3MWCuN was homogenized at six different temperatures 1000 °C, 1050 °C, 1100 °C, 1150 °C, 1205 °C, and 1250 °C for 4 hours followed by air-cooling and water quenching. In addition to these samples two temperatures, namely 1150 °C and 1205 °C, were chosen and samples were cooled at the varying rates of 500 °C/h, 750°C/h, 850 °C/h, and 1000 °C/h. Determination of the resulting ferrite/austenite ratio revealed that homogenization temperature plays the dominant role in determining the final ferrite content. Slower cooling rates drop the amount of ferrite in a linear manner that is approximately constant for the different homogenization temperatures studied. An equation is proposed to predict the ferrite content covering the homogenization temperatures from 1000 °C to 1250 °C given that the initial ferrite amount present at the homogenization T is known.