Analysis of Embrittlement in Weld Heat-affected Zone due to Formation of Martensitic Islands by Local Criterion Approach

Abstract

In the previous work, the state of the martensitic islands and its influence on the fracture toughness in low carbon steels simulated to the heat affected zone of multi-pass weld were investigated.
It has been shown by the authors that cleavage fracture toughness of steels can be described in terms of the cleavage fracture stress and yield stress of materials.
In the present work, experimental results in the previous work were analyzed along with the local criterion approach, and successful correlations were obtained. Through this correlation, the influence of the martensitic islands on the deterioration in toughness was investigated. It was suggested that the maximum size of martensitic islands was not an unique metallurgical factor which deteriorated the toughness, and mean free path and the statistical distribution of the martensitic islands had also a great influence on cleavage fracture toughness.