EBSD Study of Deformation Bands in 9- 12% Cr Martensitic Steels

M. AVALOS; J. LEDONNE; A. ROLLET

Rio de Janeiro

Congreso; 17th International Microscopy Congress IMC17; 2010

SBMM - IFSM

The stabilization of the lath-martensitic structures is essential for the improvement of the fatigue behavior of the tempered martensite in 9 – 12% Cr steels. These alloys, specially designed to fulfill operational requirements at high temperature in power plants and fusion reactor technology, exhibit attractive tensile strength properties and they are microstructurally stable during subsequent ageing. However, under cyclic loading conditions Figure 1 , these materials show a noticeable cyclic softening up to failure [1]. In this study, the Electron Backscatter Diffraction technique was utilized to evaluate the changes in local misorientations (misorientation angle between neighboring points) that could be correlated with the distribution of local plastic strain induced by cyclic plastic deformation. The development of inhomogeneities connected to local strain microzones are characterized in an EUROFER 97 martensitic steel. Cracks initiated in those grains in which the accumulated damage exceeds a certain limit.