The Use of Confocal Laser Scanning Microscopy for the 3D Quantitative Characterization of Fracture Surfaces and Cleavage Facets.

Brittle and ductile fracture surfaces of annealed low-carbon steel specimens having different grain sizes were investigated by means of confocal laser scanning microscopy (CLSM) in conjunction with conventional scanning electron microscopy (SEM) and electron backscattered diffraction (EBSD). It is shown that very informative 2- and 3D fractographic CLSM images can be obtained and compared with SEM. The fracture surfaces were quantitatively characterized in terms of the areal surface roughness and characteristic surface area. It was found that the characteristic fracture surface area rather than areal roughness can be used as a measure of fracture surface ductility. The misorientation and diameters of cleavage facets were measured and compared with initial misorientation and size of grains evaluated by EBSD. The excellent agreement was found between characteristics of fracture surface elements and the underlying microstructure. It is concluded that CLSM is the powerful tool for the qualitative and quantitative fracture surfaces analysis.