The Mottling Appeared on Radiograph of Weldments and Castings (4th Report)

Weld crack and the mottling

Abstract

It has been emphasised by the writers that a low density grain boundary containing micro cracks or impurities maybe important in regard to the mechanism of mottling. The mottled appearance is frequently observed on radiographs of austenitic stainless steel weldments.
Concerning the idea, however, there is a question how the diffraction of anx-ray beam can happen when an X-ray beam passes such a low density grain boundary.
A specimen that contains weld cracks was chosen. The specimen was subjected to a radiographic examination and a mottling that originated in a weld crack was confirmed.
The result obtained seems to suggest the soundness of putting emphasis on the importance of a low density grain boundary in the mechanism of the mottled appearance.