The significance of austenite grain size for transformation behaviour and toughness in the coarse-grain region of the heat-affected zone of fine-grain structural steels

摘要

In the course of welding fine-grain structural steels it was to be expected that both the growth of the austenite grains and the transformation behaviour would influence the toughness of the coarse-grain zone in the heat-affected zone. Therefore, the growth of the austenite grains and the transformation behaviour of some normalized, thermo-mechanically treated and quenched and tempered fine-grain structural steels was determined under simulated welding processes and linked to the toughness properties of the coarse-grain zone. To make a comparison, micro-structure and the toughness of submerged arc welds were examined. While in the case of the simulated welding situations the transformation behaviour was decisive for toughness, it was established that with the submerged arc welds, it was the growth of austenite grain size that was the critical factor.