Cracking and Failure in a High Strength Low Alloy Steel during Solidification

The present study focuses on characterizing cracks and fracture that appeared during solidification in the segregated zones of the as-cast structure of a large size ingot made of high strength low alloy steel. Solidification experiment was conducted, using Gleeble® 3800 thermo-mechanical simulator, on samples taken from the ingot/hot top interface of a 40 MT (Metric Ton) ingot. The thermal cycle consisted in heating from ambient temperature to 1385 °C with a constant heating rate of 2 °C/s followed by a free cooling. Optical and scanning electronic microscopies were used to analyze and quantify the cracked regions. Microstructural observations revealed that shrinkage during rapid solidification of melted grain boundaries ultimately led to the initiation and propagation of cracks.