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

Abstract

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.

Subsurface Crack Initiation and Propagation in an Open Dieforged High Strength Steel: A Microstructural Analysis

“…Therefore, many efforts have been devoted to better understand the origin of cracking during the manufacturing cycle and different causes have been identified such as the hot cracking [5], the development of thermal stresses [6], precipitation of secondary phases [7], segregation [8], etc. However, more attention should be given to the crack analyses in large size ingots where systematic studies are not always possible, due to the complexity of operations and associated high cost.…”