Some Micro-Observations on the Brittle Fractures of One-Pass Mild Steel Submarged-Arc-Welded Metals

Abstract

Charpy impact tests were carried out at various temperatures on the specimens of one-pass mild steel submarged-arc-welded metals in as-welded and annealed states.
It was pointed out that the specimens annealed at 800°C. had higher impact values and lower transition temperatures than the others. This fact led the author to infer that large grains of dendritic structures have decisive influences upon brittle fracture. The photomicrographs of fractured edges and fracture facets showed the validity of the inference.
Moreover, the X-ray back-reflection patterns of the brittle fractures were taken and the brittleness of these fractures were compared with each other in the light of the lattice distortions in them.