Substructure, Grain Boundaries, and Microcracks in Long-Operating Metal

Abstract

Methods of transmission diffraction electron microscopy and x-ray diffraction analysis are used for studying the damaged bent zone of a steam conduit from steel 12Kh1MF that has served for 153,688 h at a pressure of 14 MPa and a temperature of 550°C. The dislocation substructure is studied. The dislocation density and local stress fields created by dislocation charges are determined. Microcracks, pores, and large carbide particles are detected on grain boundaries. The results obtained are used for considering the causes of nucleation of microcracks in the studied part of the steam conduit.