Metallographic Examination of Gas Pipeline Steel with a Local Defect

In this paper, we study a steel sample from a gas pipeline with a local defect in the form of a corrosion pit. Possible reasons for its formation are analyzed based on the operating conditions and operating modes of the gas pipeline. The chemical analysis showed that the pipe material is steel 09Mn2Si. According to metallographic studies, that the distribution of ferrite and pearlite phases in the plane of the inner surface of the pipe was established to be uneven. The joint location of significant areas occupied only by ferrite or only by pearlite was recorded. This pronounced banding of the microstructure near the inner surface of the pipe can be the cause of the formation of local defects on the steel in places, where the aqueous phase of increased mineralization accumulates and the surface is in constant contact with it.