Speaker
Description
Within the present investigation, instrumented drop-weight tear tests were carried out on industrially produced heavy plate material that was thermomechanically rolled using two different strategies. In one case, the material was air-cooled from the final rolling temperature and in the other case it underwent accelerated cooling from above the austenite to ferrite transformation. Both rolling strategies were fine-tuned to result in a similar strength level. However, the strategies had a significant effect on the resulting microstructure of the plate material. Air cooling from the final rolling temperature in the ferrite regime resulted in a predominantly ferritic-pearlitic microstructure, while accelerated cooling from above the Ar3-temperature led to a predominantly bainitic microstructure. The microstructure was investigated by light-optical microscopy as well as electron microscopy in combination with electron backscatter diffraction. The relationship between the processing strategy, microstructure and the low-temperature toughness is discussed in light of previous experiences.