A new procedure of X-ray line profile analysis applied to study the dislocation structure and subgrain size-distributions in fatigued MANET steel

A new procedure of X-ray line profile analysis based on the dislocation mod el of strain anisotropy has been applied. The dislocation densities and the subgrain size-distributions in a MANET steel are investigated in the norma l condition and after cyclic deformation at room temperature and 250 degree s C. It has been found that the average dislocation density in the normal c ondition is rather high and does not change much after fatigue at room temp erature. After fatigue at 250 degrees C, however, the dislocation density w as found to increase considerably, probably due to the strong temperature d ependence of the mobility of dislocation in a martensitic steel. Even thoug h the subgrain size-distribution was found not to change much on fatigue at room temperature, it widened however after fatigue at 250 degrees C. (C) 2 000 Elsevier Science B.V. All rights reserved.